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Networking Tutorials

IPv6 Command line Testing & Troubleshooting in Windows

Learn how to use ipconfig command, route command, ping command, tracert command, pathping command and Netstat command for testing and troubleshooting IPv6 network in Windows system. Each command explained with its command line arguments and options.

Windows includes the following IPv6-enabled command-line tools that are most commonly used for network troubleshooting:

  • Ipconfig
  • Route
  • Ping
  • Tracert
  • Pathping
  • Netstat

Ipconfig

The ipconfig tool displays all current TCP/IP network configuration values, and it is used to perform maintenance tasks such as refreshing DHCP and DNS settings. In Windows Server 2008 and Windows Vista, the ipconfig command without options displays IPv4 and IPv6 configuration for all physical adapters and tunnel interfaces that have addresses. The following is an example display of the ipconfig command on a computer running Windows Server 2008 or Windows Vista:

c:\\> ipconfig
Windows IP Configuration
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : www.ComputerNetworkingNotes.com
IPv6 Address. . . . . . . . . . . : 2001:db8:21da:7:713e:a426:d167:37ab
Temporary IPv6 Address. . . . . . : 2001:db8:21da:7:5099:ba54:9881:2e54
Link-local IPv6 Address . . . . . : fe80::713e:a426:d167:37ab%6
IPv4 Address. . . . . . . . . . . : 157.60.14.11
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : fe80::20a:42ff:feb0:5400%6
IPv4 Default Gateway  . . . . . . : 157.60.14.1
Tunnel adapter Local Area Connection* 6:
Connection-specific DNS Suffix . :
IPv6 Address. . . . . . . . . . . : 2001:db8:908c:f70f:0:5efe:157.60.14.11
Link-local IPv6 Address . . . . . : fe80::5efe:157.60.14.11%9
Site-local IPv6 Address . . . . . : fec0::6ab4:0:5efe:157.60.14.11%1
Default Gateway . . . . . . . . . : fe80::5efe:131.107.25.1%9
fe80::5efe:131.107.25.2%9
Tunnel adapter Local Area Connection* 7:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :

Ipconfig.exe displays the IPv6 addresses before the IPv4 addresses and indicates the type of IPv6 address using the following labels:

  • IPv6 Address A global address with a permanent interface ID
  • Temporary IPv6 Address A global address with a randomly derived interface ID that has a short valid lifetime
  • Link-local IPv6 Address A link-local address with its corresponding zone ID (the interface index)
  • Site-local IPv6 Address A site-local address with its corresponding zone ID (the site ID) For more information about the different types of IPv6 addresses and the zone ID By default, the interface names containing an asterisk (*) are tunneling interfaces.

IPv6 Command line Testing & Troubleshooting in Windows

Route

The Route tool displays the entries in the local IPv4 and IPv6 routing tables and allows you to change them. The Route tool displays both the IPv4 and IPv6 routing table when you run the
route print
command. You can change entries in the IPv6 routing table with the Route.exe tool with the route add, route change, and route delete commands.

Ping

In previous versions of Windows, the Ping tool verified IPv4-level connectivity to another TCP/IP computer by sending Internet Control Message Protocol (ICMP) Echo messages. The receipt of corresponding Echo Reply messages is displayed, along with round-trip times. Ping is the primary TCP/IP tool used to troubleshoot reach ability and name resolution. The Ping tool in Windows Server 2008 and Windows Vista has been enhanced to support IPv6 in the following ways:

  • Ping uses either ICMPv4 Echo or ICMPv6 Echo Request messages to verify IPv4-based or IPv6-based connectivity.
  • Ping can parse both IPv4 and IPv6 address formats.
  • If you specify a target host by name, the addresses returned by using Windows name resolution techniques can contain both IPv4 and IPv6 addresses—in which case, by default, an IPv6 address is preferred (subject to source and destination address selection). The following is an example display of the Ping tool on a computer running Windows Server 2008 or Windows Vista for an IPv6 destination address:
C:\\>ping 2001:db8:1:f282:dd48:ab34:d07c:3914
Pinging 2001:db8:1:f282:dd48:ab34:d07c:3914 from
2001:db8:1:f282:3cec:bf16:505:eae6 with 32 bytes of data:
Reply from 2001:db8:1:f282:dd48:ab34:d07c:3914: time<1ms
Reply from 2001:db8:1:f282:dd48:ab34:d07c:3914: time<1ms
Reply from 2001:db8:1:f282:dd48:ab34:d07c:3914: time<1ms
Reply from 2001:db8:1:f282:dd48:ab34:d07c:3914: time<1ms
Ping statistics for 2001:db8:1:f282:dd48:ab34:d07c:3914:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

The following command-line options support IPv6:

  • -i HopLimit
    Sets the value of the Hop Limit field in the IPv6 header. The default value is 128. The –i option is also used to set the value of the Time-to-Live (TTL) field in the IPv4 header.
  • -R
    Forces Ping to trace the round-trip path by sending the ICMPv6 Echo Request message to the destination and to include an IPv6 Routing extension header with the sending node as the next destination.
  • -S SourceAddr
    Forces Ping to use a specified IPv6 source address.
  • -4
    Forces Ping to use an IPv4 address when the DNS name query for a host name returns both IPv4 and IPv6 addresses.
  • -6
    Forces Ping to use an IPv6 address when the DNS name query for a host name returns both IPv4 and IPv6 addresses.

Note down
The Ping -f, -v TOS, -r count, -s count, -j host-list, and -k host-list command line options are not supported for IPv6.

Tracert

The Tracert tool determines the path taken to a destination. For IPv4, Tracert sends ICMPv4 Echo messages to the destination with incrementally increasing TTL field values. For IPv6, Tracert sends ICMPv6 Echo Request messages to the destination with incrementally increasing Hop Limit field values. Tracert displays the path as the list of nearside router interfaces of the routers in the path between a source host and a destination node. The Tracert tool in Windows Server 2008 and Windows Vista has been enhanced to support IPv6 in the following ways:

  • Tracert can parse both IPv4 and IPv6 address formats.
  • If you specify a target host by name, the addresses returned using Windows name resolution techniques can contain both IPv4 and IPv6 addresses—in which case, by default, an IPv6 address is preferred (subject to source and destination address selection). The following is an example display of the Tracert tool on a computer running Windows Server 2008 or Windows Vista:
c:\\>tracert 2001:db8:1:f282:dd48:ab34:d07c:3914
Tracing route to 2001:db8:1:f282:dd48:ab34:d07c:3914 over a maximum of 30 hops
1 <1 ms <1 ms <1 ms 2001:db8:1:f241:2b0:d0ff:fea4:243d
2 <1 ms <1 ms <1 ms 2001:db8:1:f2ac:2b0:d0ff:fea5:d347
3 <1 ms <1 ms <1 ms 2001:db8:1:f282:dd48:ab34:d07c:3914
Trace complete.

The following Tracert command-line options support IPv6:

  • -R
    Forces Tracert to trace the round-trip path by sending the ICMPv6 Echo Request message to the destination, including an IPv6 Routing extension header with the sending node as the next destination
  • -S SourceAddr
    Forces Tracert to use a specified IPv6 source address
  • -4
    Forces Tracert to use an IPv4 address when the DNS name query for a host name returns both IPv4 and IPv6 addresses
  • -6
    Forces Tracert to use an IPv6 address when the DNS name query for a host name returns both IPv4 and IPv6 addresses

Note The Tracert -j host-listcommand-line option is not supported for IPv6.

Pathping

The Pathping tool provides information about network latency and network loss at intermediate hops between a source and destination. For IPv4, Pathping sends multiple ICMPv4 Echo messages to each router between a source and destination over a period of time, and then it computes results based on the packets returned from each router. For IPv6, Pathping sends ICMPv6 Echo Request messages. Because Pathping displays the degree of packet loss at any given router or link, you can determine which routers or subnets might be having network problems. Pathping performs the equivalent of the Tracert tool by identifying which routers are in the path, and then it sends messages periodically to all the routers over a specified time period and computes statistics based on the number returned from each. The Pathping tool in Windows Server 2008 and Windows Vista has been enhanced to support IPv6 in the following ways:

  • Pathping can parse both IPv4 and IPv6 address formats.
  • If you specify a target host by name, the addresses returned using Windows name resolution techniques can contain both IPv4 and IPv6 addresses—in which case, by default, an IPv6 address is preferred (subject to source and destination address selection). The following is an example display of the Pathping tool on a computer running Windows Server 2008 or Windows Vista:
C:\\>pathping 2001:db8:1:f282:dd48:ab34:d07c:3914
Tracing route to 2001:db8:1:f282:dd48:ab34:d07c:3914 over a maximum of 30 hops
0 server1.example.microsoft.com [2001:db8:1:f282:204:5aff:fe56:1006]
1 2001:db8:1:f282:dd48:ab34:d07c:3914
Computing statistics for 25 seconds...
Source to Here This Node/Link
Hop RTT Lost/Sent = Pct Lost/Sent = Pct Address
0 server1.example.microsoft.com
[2001:db8:1:f282:204:5aff:fe56:1006]
0/ 100 = 0% |
1 0ms 0/ 100 = 0% 0/ 100 = 0% 2001:db8:1:f282:dd48:ab34:d07c:
3914
Trace complete.

The following Pathping command-line options support IPv6:

  • -4
    Forces Pathping to use an IPv4 address when the DNS name query for a host name returns both IPv4 and IPv6 addresses
  • -6
    Forces Pathping to use an IPv6 address when the DNS name query for a host name returns both IPv4 and IPv6 addresses

Note The Pathping -g host-listcommand-line option is not supported for IPv6.

Netstat

The Netstat tool displays active TCP connections, ports on which the computer is listening, Ethernet statistics, the IPv4 routing table, IPv4 statistics (for the IP, ICMP, TCP, and UDP protocols), the IPv6 routing table, and IPv6 statistics (for the IPv6, ICMPv6, TCP over IPv6, and UDP over IPv6 protocols).

Displaying IPv6 Configuration with Netsh

Useful commands to display information about the IPv6 configuration of a computer running Windows Server 2008 and Windows Vista are the following:

  • Netsh interface ipv6 show interface
  • Netsh interface ipv6 show address
  • Netsh interface ipv6 show route
  • Netsh interface ipv6 show neighbors
  • Netsh interface ipv6 show destination cache

Netsh interface ipv6 show interfaceM
This command displays the list of IPv6 interfaces. By default, the interface names containing an asterisk (*) are tunneling interfaces.

Netsh interface ipv6 show address
This command displays the list of IPv6 addresses for each interface.

Netsh interface ipv6 show route
This command displays the list of routes in the IPv6 routing table.

Netsh interface ipv6 show neighbors
This command displays the contents of the neighbor cache, sorted by interface. The neighbor cache stores the link-layer addresses of recently resolved next-hop addresses.

Netsh interface ipv6 show destinationcache
This command displays the contents of the destination cache, sorted by interface. The destination cache stores the next-hop addresses for destination addresses.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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ICMPv6 Types and Messages Explained

This tutorial explains ICMPv6 types and messages such as Destination unreachable, packet too big, time exceeded, parameter problem, echo request and echo reply in detail.

Like IPv4, the specification for the Internet Protocol version 6 (IPv6) header and extension headers does not provide facilities for reporting errors. Instead, IPv6 uses an updated version of the Internet Control Message Protocol (ICMP) named ICMP version 6 (ICMPv6). ICMPv6 has the common IPv4 ICMP functions of reporting delivery and forwarding errors and providing a simple echo service for troubleshooting. ICMPv6 is defined in RFC 4443 and is required for an IPv6 implementation. The ICMPv6 protocol also provides a packet structure framework for the following:

  • Neighbor Discovery Neighbor Discovery (ND) is a series of five ICMPv6 messages that manage node-to-node communication on a link. ND replaces Address Resolution Protocol (ARP), ICMPv4 Router Discovery, and the ICMPv4 Redirect message
  • Multicast Listener Discovery Multicast Listener Discovery (MLD) is a series of three ICMPv6 messages that are equivalent to the Internet Group Management Protocol (IGMP) for IPv4 for managing subnet multicast membership.

ICMPv6 is also used by other protocols, such as Secure Neighbor Discovery (SEND). SEND is not supported by IPv6 for Windows Vista and Windows Server 2008

Types of ICMPv6 Messages

There are two types of ICMPv6 messages:

  • Error messages Error messages report errors in the forwarding or delivery of IPv6 packets by either the destination node or an intermediate router. The high-order bit of the 8-bit Type field for all ICMPv6 error messages is set to 0. Therefore, valid values for the Type field for ICMPv6 error messages are in the range of 0 through 127. ICMPv6 error messages include Destination Unreachable, Packet Too Big, Time Exceeded, and Parameter Problem.
  • Informational messages Informational messages provide diagnostic functions and additional host functionality, such as MLD and ND. The high-order bit of the 8-bit Type field for all ICMPv6 informational messages is set to 1. Therefore, valid values for the Type field for ICMPv6 information messages are in the range of 128 through 255.

ICMPv6 informational messages described in RFC 4443 include Echo Request and Echo Reply. There are additional ICMPv6 informational messages defined for Mobile IPv6.

ICMPv6 Error Messages

ICMPv6 error messages report forwarding or delivery errors by either a router or the destination host, and they consist of the following messages:

  • Destination Unreachable (ICMPv6 Type 1)
  • Packet Too Big (ICMPv6 Type 2)
  • Time Exceeded (ICMPv6 Type 3)
  • Parameter Problem (ICMPv6 Type 4)

ICMPv6 Types and Messages Explained

To conserve network bandwidth, ICMPv6 error messages are not sent for every error encountered. Instead, ICMPv6 error messages are rate limited. Although not required by RFC 4443, the recommended method for rate limiting ICMPv6 error messages is known as token bucket. There is an average rate of transmission of ICMPv6 error messages that cannot be exceeded. The rate of transmission can be based on a number of ICMPv6 error messages per second or a specified percentage of a link’s bandwidth. However, to better handle error notification for busty traffic, the node can send a number of messages in a burst, provided the number of messages in the burst does not exceed the overall transmission rate.

Destination Unreachable

A router or a destination host sends an ICMPv6 Destination Unreachable message when the packet cannot be forwarded to the destination node or upper-layer protocol. In the Destination Unreachable message, the Type field is set to 1 and the Code field is set to a value in the range of 0 through 6. Following the Checksum field is a 32-bit Unused field and the leading portion of the discarded packet, sized so that the entire IPv6 packet containing the ICMPv6 message is no larger than 1280 bytes (the minimum IPv6 MTU). The number of bytes of the discarded packet included in the message varies if there are IPv6 extension headers present. For an ICMPv6 message without extension headers, up to 1232 bytes of the discarded packet are included (1280 less a 40-byte IPv6 header and an 8-byte ICMPv6 Destination Unreachable header).

Packet Too Big

A router sends an ICMPv6 Packet Too Big message when the packet cannot be forwarded because the link MTU on the forwarding interface of the router is smaller than the size of the IPv6 packet

Time Exceeded

A router typically sends an ICMPv6 Time Exceeded message when the Hop Limit field in the IPv6 header becomes zero after decrementing its value during the forwarding process.

ICMPv6 Informational Messages

Echo Request

An IPv6 node sends an ICMPv6 Echo Request message to a destination to solicit an immediate Echo Reply message. The Echo Request/Echo Reply message facility provides a simple diagnostic function to aid in the troubleshooting of a variety of reach ability and routing problems.

Echo Reply

An IPv6 node sends an ICMPv6 Echo Reply message in response to the receipt of an ICMPv6 Echo Request message Echo Request messages can be sent to a multicast address. As specified in RFC 4443, an Echo Request message sent to a multicast address should be answered with an Echo Reply message, sent from a unicast address assigned to the interface on which the Echo Request was received. The IPv6 protocol for Windows Vista and Windows Server 2008 does not respond to multicast Echo Request messages. Echo Request messages can be sent to a multicast address. As specified in RFC 4443, an Echo Request message sent to a multicast address should be answered with an Echo Reply message, sent from a unicast address assigned to the interface on which the Echo Request was received. The IPv6 protocol for Windows Vista and Windows Server 2008 does not respond to multicast Echo Request messages.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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IPv6 Neighbor Discovery Protocol Explained

This tutorial explains IPv6 neighbor discovery protocol in detail including neighbor discovery process and router solicitation, router advertisement and redirect messages.

Internet Protocol version 6 (IPv6) Neighbor Discovery (ND) is a set of messages and processes defined in RFC 4861 that determine relationships between neighboring nodes. ND replaces Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP) router discovery, and the ICMP Redirect message used in IPv4. ND also provides additional functionality.

ND is used by nodes to do the following:

  • Resolve the link-layer address of a neighboring node to which an IPv6 packet is being forwarded.
  • Determine when the link-layer address of a neighboring node has changed.
  • Determine whether a neighbor is still reachable.

ND is used by hosts to do the following:

  • Discover neighboring routers.
  • Auto configure addresses, address prefixes, routes, and other configuration parameters.

ND is used by routers to do the following:

  • Advertise their presence, host configuration parameters, routes, and on-link prefixes.
  • Inform hosts of a better next-hop address to forward packets for a specific destination.

There are five different ND messages:

  • Router Solicitation (ICMPv6 type 133)
  • Router Advertisement (ICMPv6 type 134)
  • Neighbor Solicitation (ICMPv6 type 135)
  • Neighbor Advertisement (ICMPv6 type 136)
  • Redirect (ICMPv6 type 137)

IPv6 Neighbor Discovery Protocol Explained

Router Solicitation

The Router Solicitation message is sent by IPv6 hosts to discover the presence of IPv6 routers on the link. A host sends a multicast Router Solicitation message to prompt IPv6 routers to respond immediately, rather than waiting for an unsolicited Router Advertisement message. For example, assuming that the local link is Ethernet, in the Ethernet header of the Router Solicitation message you will find these settings:

  • The Source Address field is set to the MAC address of the sending network adapter.
  • The Destination Address field is set to 33-33-00-00-00-02. In the IPv6 header of the Router Solicitation message, you will find the following settings:
  • The Source Address field is set to either a link-local IPv6 address assigned to the sending interface or the IPv6 unspecified address (::).
  • The Destination Address field is set to the link-local scope all-routers multicast address (FF02::2).
  • The Hop Limit field is set to 255.

Router Advertisement

IPv6 routers send unsolicited Router Advertisement messages pseudo-periodically—that is, the interval between unsolicited advertisements is randomized to reduce synchronization issues when there are multiple advertising routers on a link—and solicited Router Advertisement messages in response to the receipt of a Router Solicitation message. The Router Advertisement message contains the information required by hosts to determine the link prefixes, the link MTU, specific routes, whether or not to use address autoconfiguration, and the duration for which addresses created through address autoconfiguration are valid and preferred. For example, assuming that the local link is Ethernet in the Ethernet header of the Router Advertisement message, you will find these settings:

  • The Source Address field is set to the MAC address of the sending network adapter.
  • The Destination Address field is set to either 33-33-00-00-00-01 or the unicast MAC address of the host that sent a Router Solicitation from a unicast address.

In the IPv6 header of the Router Advertisement message, you will find the following settings:

  • The Source Address field is set to the link-local address assigned to the sending interface.
  • The Destination Address field is set to either the link-local scope all-nodes multicast address (FF02::1) or the unicast IPv6 address of the host that sent the Router Solicitation message from a unicast address.
  • The Hop Limit field is set to 255.

Neighbor Solicitation

IPv6 nodes send the Neighbor Solicitation message to discover the link-layer address of an on-link IPv6 node or to confirm a previously determined link-layer address. It typically includes the link-layer address of the sender. Typical Neighbor Solicitation messages are multicast for address resolution and unicast when the reach ability of a neighboring node is being verified. For example, assuming that the local link is Ethernet, in the Ethernet header of the Neighbor Solicitation message, you will find the following settings:

  • The Source Address field is set to the MAC address of the sending network adapter.
  • For a multicast Neighbor Solicitation message, the Destination Address field is set to the Ethernet MAC address that corresponds to the solicited-node address of the target. For a unicast Neighbor Solicitation message, the Destination Address field is set to the unicast MAC address of the neighbor.

In the IPv6 header of the Neighbor Solicitation message, you will find these settings:

  • The Source Address field is set to either a unicast IPv6 address assigned to the sending interface or, during duplicate address detection, the unspecified address (::).
  • For a multicast Neighbor Solicitation, the Destination Address field is set to the solicited node address of the target. For a unicast Neighbor Solicitation, the Destination Address field is set to the unicast address of the target.

Neighbor Advertisement

An IPv6 node sends the Neighbor Advertisement message in response to a Neighbor Solicitation message. An IPv6 node also sends unsolicited Neighbor Advertisements to inform neighboring nodes of changes in link-layer addresses or the node’s role. The Neighbor Advertisement contains information required by nodes to determine the type of Neighbor Advertisement message, the sender’s role on the network, and typically the link-layer address of the sender. For example, assuming that the local link is Ethernet, in the Ethernet header of the Neighbor Advertisement message, you will find the following settings:

  • The Source Address field is set to the MAC address of the sending network adapter.
  • The Destination Address field is set, for a solicited Neighbor Advertisement, to the unicast MAC address of the initial Neighbor Solicitation sender. For an unsolicited Neighbor Advertisement, the Destination Address field is set to 33-33-00-00-00-01, which is the Ethernet MAC address corresponding to the link-local scope all-nodes multicast address.

In the IPv6 header of the Neighbor Advertisement message, you will find these settings:

  • The Source Address field is set to a unicast address assigned to the sending interface.
  • The Destination Address field is set, for a solicited Neighbor Advertisement, to the unicast IP address of the sender of the initial Neighbor Solicitation. For an unsolicited Neighbor Advertisement, the Destination Address field is set to the link-local scope all-nodes multicast address (FF02::1).
  • The Hop Limit field is set to 255.

Redirect

The Redirect message is sent by an IPv6 router to inform an originating host of a better first hop address for a specific destination. Redirect messages are sent only by routers for unicast traffic, are unicast only to originating hosts, and are processed only by hosts. For example, assuming that the local link is Ethernet, in the Ethernet header of the Redirect message, you will find the following settings:

  • The Source Address field is set to the MAC address of the sending network adapter.
  • The Destination Address field is set to the unicast MAC address of the originating sender.

In the IPv6 header of the Redirect message, you will find these settings:

  • The Source Address field is set to a unicast address that is assigned to the sending interface.
  • The Destination Address field is set to the unicast IP address of the originating host.
  • The Hop Limit field is set to 255.

Neighbor Discovery Processes

The ND protocol provides message exchanges for the following processes:

  • Address resolution (including duplicate address detection)
  • Router discovery (includes prefix and parameter discovery)
  • Neighbor unreachability detection
  • Redirect function

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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Ethernet Standards and Protocols Explained

This tutorial explains Ethernet Standards and Protocols in detail. Learn how the most common Ethernet standards (such as 10Base5, 10BaseT, 100BaseFX, 802.5-Token ring, 802.11b-Wireless, CSMA CD, etc.) are defined in computer network with their functions and purpose.

IEEE shorthand identifiers, such as 10Base5, 10Base2, 10BaseT, and 10BaseF include three pieces of information:

  • The number 10: At the front of each identifier, 10 denotes the standard data transfer speed over these media – ten megabits per second (10Mbps).
  • The word Base: Short for Baseband, this part of the identifier signifies a type of network that uses only one carrier frequency for signaling and requires all network stations to share its use.
  • The segment type or segment length: This part of the identifier can be a digit or a letter:
  • Digit – shorthand for how long (in meters) a cable segment may be before attenuation sets in. For example, a 10Base5 segment can be no more than 500 meters long.
  • Letter – identifies a specific physical type of cable. For example, the
  • T at the end of 10BaseT stands for twisted-pair.
10BaseT

One of the most common types of Ethernet in use today is 10BaseT. This particular implementation uses four-pair UTP wiring (Cat3 or higher, but most commonly you will see Cat5) using RJ-45 connectors. Each cable is connected from each network device to a central hub in a physical star topology. Within the hub, the signals are repeated and forwarded to all other nodes on the network because it is a logical bus topology. Older network interface cards are configured with jumpers to set addresses and interrupts.

Today\’s network interface cards can be managed through a diagnostic program, or automatically configure themselves through plug and play technology. There is a limit of 1024 devices on an Ethernet segment, plus you can have a maximum of 1024 network segments. A UTP cable has a maximum distance of 100 meters, which is equivalent to 328 feet.

10BaseF

10BaseF is an implementation of Ethernet 802.3 over fiber optic cabling. 10BaseF offers only 10 Mbps, even though the fiber optic media has the capacity for much faster data rates. One of the implementations of 10BaseF is to connect two hubs as well as connecting hubs to workstations. The best time to use 10BaseF is in the rewiring of a network from copper to fiber optic, when you need an intermediate protocol using the new wiring. 10BaseF is not often a permanent solution because the data rate is so low and the cabling so expensive in comparison to using UTP.

10Base2

10Base2, also called ThinNet, is one of the two Ethernet specifications that use coaxial cable. (One of the best ways to remember that 10Base2 is ThinNet, and 2 is smaller than 10Base5, which is ThickNet.) One of the most important issues to remember in an Ethernet coax wiring scheme is the 5-4-3 rule,

5-4-3 rule
which states that you can have up to five cable segments, connected by four repeaters, with no more than three of these segments being mixing segments. In the days of coaxial cable networks, this meant that you could have up to three mixing segments of 500 or 185 meters each (for 10Base5 and 10Base2, respectively) populated with multiple computers and connected by two repeaters. You could also add two additional repeaters to extend the network with another two cable segments of 500 or 185 meters each, as long as these were link segments connected directly to the next repeater in line, with no intervening computers,

A 10Base2 network could therefore span up to 925 meters and a 10Base5 network up to 2,500 meters which states that there can only be 5 segments in a series and 4 repeaters between these 5 segments, although only 3 of the segments can be populated with devices. 10Base2 uses BNC connectors and is implemented as both a physical and logical bus topology using RG-58 cabling.

The minimum distance for cables between workstations must be at least a half-meter. Drop cables should not be used to connect a BNC connector to the network interface card (NIC) because this will cause signaling problems unless the NIC is terminated. 10Base2 ThinNet segments cannot be longer than 185 meters, although it is often exaggerated to 200 meters, and you can\’t put more than 30 devices on each populated segment. The entire cabling scheme, including all five segments, can\’t be longer than 925 meters.



10Base5

10Base5 is nearly identical to 10Base2, except that it uses a different type of cabling and media connector. 10Base5 is known as ThickNet because it uses the RG-8 coaxial cable. It requires an external transceiver to attach to the network interface card on each device. The transceiver is a device that translates the workstation\’s digital signal to a baseband cabling format. ThinNet and UTP network interface cards have built-in transceivers. Only 10Base5 ThickNet network interfaces use external transceivers. In the 10Base5 configuration, the NIC attaches to the external transceiver using an AUI connector. The transceiver then clamps into the ThickNet cabling, which is why it is usually called a vampire tap. 10Base5 can also use BNC connectors. For 10Base5, the following rules apply: First the 5-4-3 rule applies to ThickNet just as it did to ThinNet. In addition, the minimum cable distance between each transceiver is 2.5 meters. The maximum network segment length is 500 meters, which is where 10Base5 gets the \”5\” in its name. The entire set of five segments cannot exceed 2,500 meters. You can have 100 devices on a 10Base5 network segment.

100BaseFX

100BaseFX is simply Fast Ethernet over fiber. Originally, the specification was known as 100Base-X over CDDI (Copper Data Digital Interface) or FDDI (Fiber Data Digital Interface). Because the signaling is so vastly different, these two technologies were split into 100BaseFX and 100BaseTX. 100BaseFX runs over multimode fiber. There are two types of fiber in use. Multimode fiber optic cables use LEDs to transmit data and are thick enough that the light signals bounce off the walls of the fiber. The dispersion of the signal limits the length of multimode fiber. Single mode fiber optic cables use injected lasers to transmit the data along fiber optic cable with an extremely small diameter. Because the laser signal can travel straight without bouncing and dispersing, the signal can travel much farther than multimode.

100BaseT4

100BaseT4 was the specification created to upgrade 10BaseT networks over Cat3 wiring to 100 Mbps without having to replace the wiring. Using four pairs of twisted pair wiring, two of the four pairs are configured for half-duplex transmission (data can move in only one direction at a time). The other two pairs are configured as simplex transmission, which means data moves only in one direction on a pair all the time.

100BaseTX

100BaseTX, Fast Ethernet, transmits data at 100 Mbps. Leveraging the existing IEEE 802.3u standard rules, Fast Ethernet works nearly identically to 10BaseT, including that it has a physical star topology using a logical bus. 100BaseTX requires Cat5 UTP.

Gigabit Ethernet

The fastest form of Ethernet is currently Gigabit Ethernet, also known as 1000BaseT over Cat5 or highergrade cable, using all four pairs of the cable. It uses a physical star topology with logical bus. There is also 1000BaseF, which runs over multimode fiber optic cabling. Data transmission is full-duplex, but half-duplex is also supported.

Specify the characteristics (For example: speed, length, topology, and cable type) of the following cable standards:
  • 10BASE-T and 10BASE-FL
  • 100BASE-TX and 100BASE-FX
  • 1000BASE-T, 1000BASE-CX, 1000BASE-SX and 1000BASE-LX
  • 10 GBASE-SR, 10 GBASE-LR and 10 GBASE-ER
Designation Supported Media Maximum Segment Length Transfer Speed Topology
10Base-5 Coaxial 500m 10Mbps Bus
10Base-2 ThinCoaxial (RG-58 A/U) 185m 10Mbps Bus
10Base-T Category3 or above unshielded twisted-pair (UTP) 100m 10Mbps Star,using either simple repeater hubs or Ethernet switches
1Base-5 Category3 UTP, or above 100m 1Mbps Star,using simple repeater hubs
10Broad-36 Coaxial(RG-58 A/U CATV type) 3600m 10Mbps Bus(often only point-to-point)
10Base-FL Fiber-optic- two strands of multimode 62.5/125 fiber 2000m (full-duplex) 10Mbps Star(often only point-to-point)
100Base-TX Category5 UTP 100m 100Mbps Star,using either simple repeater hubs or Ethernet switches
100Base-FX Fiber-optic- two strands of multimode 62.5/125 fiber 412 meters (Half-Duplex), 2000 m (full-duplex) 100 Mbps, (200 Mb/s full-duplex mode) Star(often only point-to-point)
1000Base-SX Fiber-optic- two strands of multimode 62.5/125 fiber 260m 1Gbps Star,using buffered distributor hub (or point-to-point)
1000Base-LX Fiber-optic- two strands of multimode 62.5/125 fiber or monomode fiber 440m (multimode) 5000 m (singlemode) 1Gbps Star,using buffered distributor hub (or point-to-point)
1000Base-CX Twinax,150-Ohm-balanced, shielded, specialty cable 25m 1Gbps Star(or point-to-point)
1000Base-T Category5 100m 1Gbps Star
802.5 (token ring)



The IEEE 802.5 Token Ring standards define services for the OSI physical layer and the MAC sublayer of the data link layer. Token Ring computers are situated on a continuous network loop. A Token Ring controls access to the network by passing a token, from one computer to the next. Before they can transmit data they must wait for a free token, thus token passing does not allow two or more computers to begin transmitting at the same time.

  • Token Ring has some major advantages over Ethernet:
  • The maximum frame size for Token Ring is 4k, which is much more efficient that the small Ethernet maximum.
  • Token Ring has long-distance capability.
  • Every station in the ring is guaranteed access to the token at some point; thus, every station can transmit data.
  • Error detection and recovery techniques are also enhanced in a Token Ring environment by using a monitor function normally controlled by a server. For example, if the token is lost or corrupted, the protocol provides a mechanism to generate a new token after a specified time interval has elapsed.
Media MAC Method Signal Propagation Method Speed Topologies Maximum Connections
Twisted-pair(various types) Token passing Forwarded from device to device (or port to port on a hub) in a closed loop 4Mbps

16 Mbps

Ring

Star-using Token Ring repeater hubs

255nodes per segment
802.11b (wireless)

802.11b is a wireless Ethernet technology operating at 11MB. 802.11b devices use Direct Sequence Spread Spectrum (DSSS) radio technology operating in the 2.4GHz frequency band. An 802.11b wireless network consists of wireless NICs and access points. Access points act as wireless hubs to link multiple wireless NICs into a single subnet. Access points also have at least one fixed Ethernet port to allow the wireless network to be bridged to a traditional wired Ethernet network.. Wireless and wired devices can coexist on the same network. 802.11b devices can communicate across a maximum range of 50-300 feet from each other.

FDDI networking technologies

Fiber Distributed Data Interface, shares many of the same features as token ring, such as a token passing, and the continuous network loop configuration. But FDDI has better fault tolerance because of its use of a dual, counter-rotating ring that enables the ring to reconfigure itself in case of a link failure. FDDI also has higher transfer speeds, 100 Mbps for FDDI, compared to 4 – 16 Mbps for Token Ring. Unlike Token Ring, which uses a star topology, FDDI uses a physical ring. Each device in the ring attaches to the adjacent device using a two stranded fiber optic cable. Data travels in one direction on the outer strand and in the other direction on the inner strand. When all devices attached to the dual ring are functioning properly, data travels on only one ring. FDDI transmits data on the second ring only in the event of a link failure.

Media MAC Method Signal Propagation Method Speed Topologies Maximum Connections
Fiber-optic Token passing Forwardedfrom device to device (or port to port on a hub) in a closed loop 100 Mbps Double ringStar 500 nodes

In this section we would discuss about media protocols, media standards. Later we would explore how system gets access over media and how topology works.

  • Access method
  • CSMA / CD (Carrier Sense Multiple Access / Collision Detection)
  • CSMA / CA (Carrier Sense Multiple Access/Collision Avoidance)
  • Topology
  • Media
  • Speed

Gaining Access to the Media

Media access methods are independent of the physical and logical topologies. You will find that there are usually just a few combinations that seem to work well, however. Media access methods are simply the rules that govern how a device can submit data to the network. Each access method will have a different effect on network traffic.

Contention as a Method of Media Access

Contention, often called random access, is the media access method that acts as an open door to anyone who wants to walk in. Two types of contention methods exist for media access; they are similar, but a single difference between them changes how efficiently they operate. They are:

  • CSMA/CD (Carrier Sense Multiple Access / Collision Detection)
  • CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance)
CSMA/CD

In a traditional, or hub-based, Ethernet environment, only one NIC can successfully send a frame at a time. All NICs, however, can simultaneously listen to information on the wire. Before an Ethernet NIC puts a frame on the wire, it will first sense the wire to ensure that no other frame is currently on the wire. If the cable uses copper, the NIC can detect this by examining the voltage levels on the wire. If the cable is fiber, the NIC can detect this by examining the light frequencies on the wire. The NIC must go through this sensing process, since the Ethernet medium supports

csma cd

multiple access

another NIC might already have a frame on the wire. If the NIC doesn\’t sense a frame on the wire, it will transmit its own frame; otherwise, if a frame is found on the wire, the NIC will wait for the completion of the transmission of the frame and then transmit its own frame.

Collision Detection

If two or more devices simultaneously sense the wire and see no frame, and each places its frame on the wire, a collision will occur. In this situation, the voltage levels on a copper wire or the light frequencies on a piece of fiber get messed up. For example, if two NICs attempt to put the same voltage on an electrical piece of wire, the voltage level will be different from that of only one device. Basically, the two original frames become unintelligible (or indecipherable). The NICs, when they place a frame on the wire, examine the status of the wire to ensure that a collision does not occur: this is the collision detection mechanism of CSMA/CD.

If the NICs see a collision for their transmitted frames, they have to resend the frames. In this instance, each NIC that was transmitting a frame when a collision occurred creates a special signal, called a jam signal on the wire. It then waits a small random time period, and senses the wire again. If no frame is currently on the wire, the NIC will then retransmit its original frame. The time period that the NIC waits is measured in microseconds, a delay that can\’t be detected by a human. Likewise, the time period the NICs wait is random to help ensure a collision won\’t occur again when these NICs retransmit their frames. The more devices you place on an Ethernet segment, the more likely you will experience collisions. If you put too many devices on the segment, too many collisions will occur, seriously affecting your throughput. Therefore, you need to monitor the number of collisions on each of your network segments. The more collisions you experience, the less throughput you will get.

CSMA/CA

WLANs use a mechanism called Carrier Sense, Multiple Access/Collision Avoidance (CSMA/CA). Unlike Ethernet, it is impossible to detect collisions in a wireless medium. In a WLAN, a device cannot simultaneously send or receive and thus cannot detect a collision: it can only do one or the other. To avoid collisions, a device will use Ready-to-Send (RTS) and Clear-to-Send (CTS) signals. When a device is ready to transmit, it first senses the airwaves for a current signal. If there is none, it generates an RTS signal, indicating that data is about to send. It then sends its data and finishes by sending a CTS signal, indicating that another wireless device can now transmit.

Ethernet (802.3) and LLC (802.2)

There are two ways that specifications become standards. One is through standardized development, and the other is through common usage of a proprietary specification, where the usage becomes so prevalent that the specification is adopted as a standard. Ethernet is the latter. The IEEE was not the first to develop Ethernet. That honor goes to the research and development efforts of three companies in the 1970s: Digital, Intel, and Xerox, which were known collectively as DIX. Later on, the IEEE based its 802.3 standard on the DIX specification. In return, DIX updated its implementation to match the small changes made by the IEEE.

Nowadays, Ethernet is used for these and several other specifications. Ethernet 802.3 is generally implemented in conjunction with 802.2. The system uses the CSMA/CD media access method, with a logical bus topology. Physically, Ethernet can be either a star or a bus. It can use copper coaxial cabling, UTP, and fiber optics. Since Ethernet uses the broadcast system of a bus topology, each node receives every data message and examines the frame header to see whether the message is meant to be received by it. If not, the frames are discarded; if so, the frames are passed on to upper layer protocols so that the receiving application can act on them.

Data Link Layer Name IEEE Standard Description
Top part Logical Link Control (LLC) 802.2

Defines how to multiplex multiple network layer protocols in the data link layer frame, which doesn\’t have to be Ethernet. LLC is performed in software.

Bottom part Media Access Control (MAC) 802.3

Defines how information is transmitted in an Ethernet environment and defines the framing, MAC addressing, and mechanics as to how Ethernet works. MAC is performed in hardware.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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Categories
Networking Tutorials

Types of Network Protocols Explained with Functions

This tutorial explains types of network protocols and their functions in details. Understanding these basic network protocols with functions will help you in managing network effectively. Learn how the most common types of network protocols works in computer network.

TCP and UDP

The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) are used to transmit network data to and from server and client applications. The main difference between the two protocols is that TCP uses a connection-oriented transport, while UDP uses a connectionless type of communication. When the TCP protocol is used, a special connection is opened up between two network devices, and the channel remains open to transmit data until it is closed.

On the other hand, a UDP transmission does not make a proper connection and merely broadcasts its data to the specified network address without any verification of receipt. For certain types of applications and services, a TCP connection makes more sense, while other types are more efficiently provided by UDP communication. The advantage of TCP is that the transmission is much more reliable because it uses acknowledgement packets to ensure delivery. The advantage of UDP is that there is no connection, so it is much faster without all the checks and acknowledgements going on, but is also less reliable. In Table some common TCP/IP applications are shown with the type of protocol they use.

Protocol Common Port
FTP (File Transfer Protocol) 20, 21
SSH (Secure Shell) 22
Telnet 23
SMTP (Simple Mail Transfer Protocol) 25
DNS (Domain Name Service) 53
TFTP (Trivial File Transfer Protocol) 69
HTTP (Hypertext Transfer Protocol) 80
POP3 (Post Office Protocol version 3) 110
NNTP (Network News Transport Protocol) 119
NTP (Network Time Protocol) 123
IMAP4 (Internet Message Access Protocol version 4) 143
HTTPS (Hypertext Transfer Protocol Secure) 443
DNS



TCP/IP networks communicate with hosts using their IP addresses. It would be very difficult for someone to have to memorize the different IP addresses for the hosts they want to connect to on the network. A Domain Name Service (DNS) makes it easier to identify a host by a domain name. A domain name uses words rather than numbers to identify Internet hosts. Suppose you want to connect to the CompTIA Web site by using your Web browser. You would enter

http://www.comptia.org

In the address bar to go to the Comp TIA Web page. www.comptia.org would be a common name used for a numerical IP address. You could use 216.119.103.72 instead, but www.comptia.org is easier to remember. A DNS server translates these addresses. Your Web browser asks the TCP/IP protocol to ask the DNS server for the IP address of www.comptia.org. When the browser receives the address, it connects to the Web site. Remember that DNS stands for Domain Name System (or Domain Name Service) and that a DNS server translates domain names into their IP addresses.

NAT (Network Address Translation)

NAT translates one IP address to another. This can be a source address or a destination address. Two basic implementations of NAT can be used: static and dynamic

Static NAT

With static NAT, a manual translation is performed by an address translation device, translating one IP address to a different one. Typically, static NAT is used to translate destination IP addresses in packets as they come into your network, but you can translate source addresses also.

Dynamic NAT

With static address translation, you need to build the translations manually. If you have 1000 devices, you need to create 1000 static entries in the address translation table, which is a lot of work. Typically, static translation is done for inside resources that outside people want to access. When inside users access outside resources, dynamic translation is typically used. In this situation, the global address assigned to the internal user isn’t that important, since outside devices don’t directly connect to your internal users—they just return traffic to them that the inside user requested.

ICS (Internet Connection Sharing)

ICS (Internet Connection Sharing) is a built-in feature of Windows 98 Second Edition, Windows 2000, Windows Me, and Windows Xp. ICS provides networked computers with the capability to share a single connection to the Internet. Multiple users can use ICS to gain access to the Internet through a single connection by using Dial-Up Networking or local networking.

WINS (Windows Internet Name Service)

While DNS resolves host names to IP addresses, WINS resolves NetBIOS names to IP addresses. Windows Internet Name Service provides a dynamic database of IP address to NetBIOS name resolution mappings. WINS, determines the IP address associated with a particular network computer. This is called name resolution. WINS supports network client and server computers running Windows. WINS uses a distributed database that is automatically updated with the names of computers currently available and the IP address assigned to each one. DNS is an alternative for name resolution suitable for network computers with fixed IP addresses.

SNMP (Simple Network Management Protocol)

Simple Network Management Protocol, is a TCP/IP protocol for monitoring networks and network components. SNMP uses small utility programs called agents to monitor behavior and traffic on the network, in order to gather statistical data. These agents can be loaded onto managed devices such as hubs, NIC\’s, servers, routers, and bridges. The gathered data is stored in a MIB (management information base). To collect the information in a usable form, a management program console polls these agents and downloads the information from their MIB\’s, which then can be displayed as graphs, charts and sent to a database program to be analyzed.

NFS (Network File System)

Network File System (NFS) is a distributed file system that allows users to access files and directories located on remote computers and treat those files and directories as if they were local.

Zeroconf (Zero configuration)

Zero Configuration Networking is a set of techniques that automatically create a usable IP network without configuration or special servers. This allows unknowledgeable users to connect computers, networked printers, and other items together and expect them to work automatically. Without Zeroconf or something similar, a knowledgeable user must either set up special servers, like DHCP and DNS, or set up each computer\’s network settings manualy.
Zeroconf currently solves three problems :

  • Choose numeric network addresses for networked items
  • Figure out which computer has a certain name
  • Figure out where to get services, like printing.
SMB (Server Message Block)



A file-sharing protocol designed to allow networked computers to transparently access files that reside on remote systems over a variety of networks. The SMB protocol defines a series of commands that pass information between computers. SMB uses four message types: session control, file, printer, and message. It is mainly used by Microsoft Windows equipped computers. SMB works through a client-server approach, where a client makes specific requests and the server responds accordingly. One section of the SMB protocol is specifically for filesystem access, such that clients may make requests to a file server. The SMB protocol was optimised for local subnet usage, but one could use it to access different subnets across the Internet on which MS Windows file-and-print sharing exploits usually focus. Client computers may have their own hard disks, which are not publicly shared, yet also want access to the shared file systems and printers on the server, and it is for this primary purpose that SMB is best known and most heavily used.

AFP (Apple File Protocol)

The file sharing protocol used in an AppleTalk network. In order for non-Apple networks to access data in an AppleShare server, their protocols must translate into the AFP language. AFP versions 3.0 and greater rely exclusively on TCP/IP (port 548 or 427) for establishing communication, supporting AppleTalk only as a service discovery protocol. The AFP 2.x family supports both TCP/IP and AppleTalk for communication and service discovery.

LPD (Line Printer Daemon) and Samba)

LPD is the primary UNIX printing protocol used to submit jobs to the printer. The LPR component initiates commands such as \”print waiting jobs,\” \”receive job,\” and \”send queue state,\” and the LPD component in the print server responds to them. The most common implementations of LPD are in the official BSD UNIX operating system and the LPRng project. The Common Unix Printing System (or CUPS), which is more common on modern Linux distributions, borrows heavily from LPD. Unix and Mac OS X Servers use the Open Source SAMBA to provide Windows users with Server Message Block (SMB) file sharing.

WAN (Wide Area Networks) technologies:

Circuit-switched

services provide a temporary connection across a phone circuit. In networking, these are typically used for backup of primary circuits and for temporary boosts of bandwidth.

dedicated circuit

dedicated circuit is a permanent connection between two sites in which the bandwidth is dedicated to that company’s use. These circuits are common when a variety of services, such as voice, video, and data, must traverse the connection and you are concerned about delay issues with the traffic and guaranteed bandwidth.

Cell-switched

cell-switched services can provide the same features that dedicated circuits offer. Their advantage over dedicated circuits is that a single device can connect to multiple devices on the same interface. The downside of these services is that they are not available at all locations, they are difficult to set up and troubleshoot, and the equipment is expensive when compared to equipment used for dedicated circuits.

Packet switching

Packet-switched services are similar to cell-switched services. Whereas cell-switched services switch fixed-length packets called cells, packet-switched services switch variable-length packets. This feature makes them better suited for data services, but they can nonetheless provide some of the QoS features that cell-switched services provide. Packet switching offers more efficient use of a telecommunication provider\’s network bandwidth. With packet switching, the switching mechanisms on the network route each data packet from switch to switch individually over the network using the best-available path. Any one physical link in a packet-switched network can carry packets from many different senders and for many different destinations. Where as in a circuit switched connection, the bandwidth is dedicated to one sender and receiver only.

ISDN (Integrated Services Digital Network)

Integrated Services Digital Network adapters can be used to send voice, data, audio, or video over standard telephone cabling. ISDN adapters must be connected directly to a digital telephone network. ISDN adapters are not actually modems, since they neither modulate nor demodulate the digital ISDN signal. Like standard modems, ISDN adapters are available both as internal devices that connect directly to a computer\’s expansion bus and as external devices that connect to one of a computer\’s serial or parallel ports. ISDN can provide data throughput rates from 56 Kbps to 1.544 Mbps using a T1 service. ISDN hardware requires a NT (network termination) device, which converts network data signals into the signaling protocols used by ISDN. Some times, the NT interface is included, or integrated, with ISDN adapters and ISDN-compatible routers. In other cases, an NT device separate from the adapter or router must be implemented. ISDN works at the physical, data link, network, and transport layers of the OSI Model.

FDDI (Fiber Distributed Data Interface)

Fiber Distributed Data Interface, shares many of the same features as token ring, such as a token passing, and the continuous network loop configuration. But FDDI has better fault tolerance because of its use of a dual, counter-rotating ring that enables the ring to reconfigure itself in case of a link failure. FDDI also has higher transfer speeds, 100 Mbps for FDDI, compared to 4 – 16 Mbps for Token Ring. Unlike Token Ring, which uses a star topology, FDDI uses a physical ring. Each device in the ring attaches to the adjacent device using a two stranded fiber optic cable. Data travels in one direction on the outer strand and in the other direction on the inner strand. When all devices attached to the dual ring are functioning properly, data travels on only one ring. FDDI transmits data on the second ring only in the event of a link failure.

Media MAC Method Signal Propagation Method Speed Topologies Maximum Connections
Fiber-optic Token passing Forwarded from device to device (or port to port on a hub) in a closed loop 100 Mbps Double ring Star 500 nodes
T1 (T Carrier level 1)

A 1.544 Mbps point to point dedicated, digital circuit provided by the telephone companies. T1 lines are widely used for private networks as well as interconnections between an organizations LAN and the telco. A T1 line uses two pairs of wire one to transmit, and one to receive. and time division multiplexing (TDM) to interleave 24 64-Kbps voice or data channels. The standard T1 frame is 193 bits long, which holds 24 8-bit voice samples and one synchronization bit with 8,000 frames transmitted per second. T1 is not restricted to digital voice or to 64 Kbps data streams. Channels may be combined and the total 1.544 Mbps capacity can be broken up as required.

T3 (T Carrier level 3)

A T3 line is a super high-speed connection capable of transmitting data at a rate of 45 Mbps. A T3 line represents a bandwidth equal to about 672 regular voice-grade telephone lines, which is wide enough to transmit real time video, and very large databases over a busy network. A T3 line is typically installed as a major networking artery for large corporations, universities with high-volume network traffic and for the backbones of the major Internet service providers.

OCx (Optical Carrier)

Optical Carrier, designations are used to specify the speed of fiber optic networks that conforms to the SONET standard.

Level Speed
OC-1 51.85
Mbps
OC-3 155.52
Mbps
OC-12 622.08
Mbps
OC-24 1.244
Gbps
OC-48 2.488
Gbps
X.25

X.25 is a network layer protocol that runs across both synchronous and asynchronous physical circuits, providing a lot of flexibility for your connection options. X.25 was actually developed to run across unreliable medium. It provides error detection and correction, as well as flow control, at both the data link layer (by LAPB) and the network layer (by X.25). In this sense, it performs a function similar to what TCP, at the transport layer, provides for IP. Because of its overhead, X.25 is best delegated to asynchronous, unreliable connections. If you have a synchronous digital connection, another protocol, such as Frame Relay or ATM, is much more efficient. An X.25 network transmits data with a packet-switching protocol, bypassing noisy telephone lines. This protocol relies on an elaborate worldwide network of packet-forwarding nodes that can participate in delivering an X.25 packet to its designated address.

Internet access technologies:

xDSL (Digital Subscriber Line)

xDSL is a term referring to a variety of new Digital Subscriber Line technologies. Some of these varieties are asymmetric with different data rates in the downstream and upstream directions. Others are symmetric. Downstream speeds range from 384 Kbps (or \”SDSL\”) to 1.5-8 Mbps (or \”ADSL\”).

Asymmetric Digital Subscriber Line (ADSL)

A high-bandwidth digital transmission technology that uses existing phone lines and also allows voice transmissions over the same lines. Most of the traffic is transmitted downstream to the user, generally at rates of 512 Kbps to about 6 Mbps.

Broadband Cable (Cable modem)

Cable modems use a broadband connection to the Internet through cable television infrastructure. These modems use frequencies that do not interfere with television transmission.

POTS / PSTN

(Plain Old Telephone Service / Public Switched Telephone Network) POTS / PSTN use modem\’s, which is a device that makes it possible for computers to communicate over telephone lines. The word modem comes from Modulate and Demodulate. Because standard telephone lines use analog signals, and computers digital signals, a sending modem must modulate its digital signals into analog signals. The computers modem on the receiving end must then demodulate the analog signals into digital signals. Modems can be external, connected to the computers serial port by an RS-232 cable or internal in one of the computers expansion slots. Modems connect to the phone line using standard telephone RJ-11 connectors.

Wireless

A wireless network consists of wireless NICs and access points. NICs come in different models including PC Card, ISA, PCI, etc. Access points act as wireless hubs to link multiple wireless NICs into a single subnet. Access points also have at least one fixed Ethernet port to allow the wireless network to be bridged to a traditional wired Ethernet network, such as the organization’s network infrastructure. Wireless and wired devices can coexist on the same network.

  • WLAN (Wireless Local Area Network) A group of computers and associated devices that communicate with each other wirelessly.
  • WPA (Wi-Fi Protected Access) A security protocol for wireless networks that builds on the basic foundations of WEP. It secures wireless data transmission by using a key similar to WEP, but the added strength of WPA is that the key changes dynamically. The changing key makes it much more difficult for a hacker to learn the key and gain access to the network.
  • WPA2 (Wi-Fi Protected Access 2) WPA2 is the second generation of WPA security and provides a stronger encryption mechanism through Advanced Encryption Standard (AES), which is a requirement for some government users.
  • WPA-Personal A version of WPA that uses long and constantly changing encryption keys to make them difficult to decode.
  • WPA-Enterprise A version of WPA that uses the same dynamic keys as WPA-Personal and also requires each wireless device to be authorized according to a master list held in a special authentication server.

A MAC address is 48 bits long and is represented as a hexadecimal number. Represented in hex, it is 12 characters in length, where each character is 4 bits. To make it easier to read, the MAC address is represented in a dotted hexadecimal format, like this: FFFF. FFFF.FFFF.

Some formats use a colon (:) instead; and in Some cases, the colon separator is spaced after every two hexadecimal digits, like this: FF:FF:FF:FF:FF:FF. the first six digits of a MAC address are associated with the vendor, or maker, of the NIC.

Each vendor has one or more unique sets of six digits. These first six digits are commonly called the organizationally unique identifier (OUI). The last six digits are used to represent the NIC uniquely within the OUI value. In theory, each NIC has a unique MAC address. In reality however, this is probably not true. What is important for your purposes is that each of your NICs has a unique MAC address within the same physical or logical segment.

A logical segment is a virtual LAN (VLAN) and is referred to as a broadcast domain .

Some devices, such as Cisco routers, might allow you to change the MAC address for a NIC, while others won\’t.

Every data link layer frame has two MAC addresses: a source MAC address of the host creating the frame and a destination MAC address for the device (or devices, in the cast of a broadcast or multicast) intended to receive the frame.

If only one device is to receive the frame, a unicast destination MAC address is used. If all devices need to receive the frame, a destination broadcast address is used.

When all the binary bits are enabled for a MAC address, this is referred to as a local broadcast address: FFFF.FFFF.FFFF.

Network protocols in terms of routing, addressing schemes, interoperability and naming conventions:

type of network protocol

TCP/IP

Transmission Control Protocol, A connection based Internet protocol responsible for breaking data into packets, which the IP protocol sends over the network. IP is located at the TCP/IP Internet layer which corresponds to the network layer of the OSI Model. IP is responsible for routing packets by their IP address.

IP is a connectionless protocol. which means, IP does not establish a connection between source and destination before transmitting data, thus packet delivery is not guaranteed by IP. Instead, this must be provided by TCP. TCP is a connection based protocol and, is designed to guarantee delivery by monitoring the connection between source and destination before data is transmitted. TCP places packets in sequential order and requires acknowledgment from the receiving node that they arrived properly before any new data is sent.

TCP/IP model
Application layer DHCP – DNS – FTP – HTTP – IMAP4 – IRC – NNTP – XMPP – MIME – POP3 – SIP – SMTP – SNMP – SSH – TELNET – BGP – RPC – RTP – RTCP – TLS/SSL – SDP – SOAP – L2TP – PPTP
Transport layer This layer deals with opening and maintaining connections, ensuring that packets are in fact received. This is where flow-control and connection protocols exist, such as: TCP – UDP – DCCP – SCTP – GTP
Network layer IP (IPv4 – IPv6) – ARP – RARP – ICMP – IGMP – RSVP – IPSec – IPX/SPX
Data link layer ATM – DTM – Ethernet – FDDI – Frame Relay – GPRS – PPP
Physical layer Ethernet physical layer – ISDN – Modems – PLC – RS232 – SONET/SDH – G.709 – Wi-Fi
IPX/SPX

IPX/SPX is the primary protocol of Novell NetWare (in particular, versions 4.0 and earlier, though it can be used on all versions). Internetwork Packet Exchange/Sequenced Packet Exchange developed by Novell and is used primarily on networks that use the Novell NetWare network operating system. The IPX and SPX protocols provide services similar to those offered by IP and TCP. Like IP, IPX is a connectionless network layer protocol. SPX runs on top of IPX at the transport layer and, like TCP, provides connection oriented, guaranteed delivery. IPX/SPX provides many of the same features as TCP/IP, and is a routable transport protocol that allows networks to be segmented. However, network segmentation with IPX/SPX is done with network numbers and not with subnet masks. IPX/SPX is also similar to TCP/IP because IPX/SPX relies on internal protocols for network communication.

IPX

IPX is similar to the operation of UDP of TCP/IP. IPX is a connectionless datagram transfer service. Because it is connectionless, like UDP, it does not require any preliminary connection setup to transmit the data packets. A disadvantage to connectionless communication is that flow control and error correction are not provided during network communication. In addition, packet delivery is not guaranteed. IPX also provides addressing and routing of packets within and between network segments.

SPX

SPX is similar to the operation of TCP of TCP/IP. SPX is connection-oriented data transfer over IPX. Because SPX is connection oriented, flow control and error correction are provided along with packet delivery acknowledgments. SPX allows a single packet to remain unacknowledged at one time. If a packet is unacknowledged, the packet is retransmitted a total of 8 times. If there’s no acknowledgment, SPX considers the connection failed.

SPXII

SPXII is an enhancement to SPX. SPXII has several improvements over SPX. SPXII allows more than one packet to remain unacknowledged. SPXII also allows for a larger packet size, which improves network performance by reducing the number of acknowledgment packets placed on the network.

NetBEUI

NetBIOS Enhanced User Interface was designed as a small, efficient protocol for use in department-sized LANs of 20-200 computers that do not need to be routed to other subnets. NetBEUI is used almost exclusively on small, non-routed networks. A LAN-only (non-routable) protocol used in early Windows networks based on the NetBIOS API, NetBEUI is a Windows protocol that even Microsoft doesn\’t recommend for any but the most isolated networks. NetBEUI isn\’t required for NetBIOS functionality. As an extension of NetBIOS, NetBEUI is not routable, therefore networks supporting NetBEUI must be connected with bridges, rather than routers, like NetBIOS, the NetBEUI interface must be adapted to routable protocols like TCP/IP for communication over WANs.

AppleTalk

The AppleTalk routing protocol is, amazing as it may sound, used by Macintosh networks. There are two important factors to understand about the AppleTalk protocol: zones and network numbers. AppleTalk network numbers assign AppleTalk networks unique numerical values that identify them as segments. Clients and servers can be part of only one network number. Because AppleTalk is routable, clients can access servers from any network number. AppleTalk also uses zones to aid clients in browsing an AppleTalk network. Zones allow servers, printers, and clients to be grouped logically for the purpose of resource access. Unlike network numbers, servers, printers, and clients can be part of more than one zone. Having membership in more than one zone allows clients easier access to network resources. Clients need not use the Chooser to view the resources of multiple zones.

TCP (Transmission Control Protocol)

Transmission Control Protocol uses a reliable delivery system to deliver layer 4 segments to the destination. This would be analogous to using a certified, priority, or next-day service with the Indian Speed Post;Service.

For example, with a certified letter, the receiver must sign for it, indicating the destination actually received the letter: proof of the delivery is provided. TCP operates under a similar premise: it can detect whether or not the destination received a sent segment. With the postal example, if the certified letter got lost, it would be up to you to resend it; with TCP, you don’t have to worry about what was or wasn’t received—TCP will take care of all the tracking and any necessary resending of lost data for you.

TCP’s main responsibility is to provide a reliable full-duplex, connection-oriented, logical service between two devices.

TCP goes through a three-way handshake to establish a session before data can be sent. Both the source and destination can simultaneously send data across the session. It uses windowing to implement flow control so that a source device doesn\’t overwhelm a destination with too many segments. It supports data recovery, where any missed or corrupted information can be re-sent by the source. Any packets that arrive out of order, because the segments traveled different paths to reach the destination, can easily be reordered, since segments use sequence numbers to keep track of the ordering.

UDP (User Datagram Protocol)

UDP uses a best-effort delivery system, similar to how first class and lower postal services of the Indian Postal Service work. With a first class letter (post card), you place the destination address and put it in your mailbox, and hope that it arrives at the destination.

With this type of service, nothing guarantees that the letter will actually arrive at the destination, but in most instances, it does. If, however, the letter doesn’t arrive at the destination, it’s up to you, the letter writer, to resend the letter: the post office isn’t going to perform this task for you.

UDP operates under the same premise: it does not guarantee the delivery of the transport layer segments. While TCP provides a reliable connection, UDP provides an unreliable connection.

UDP doesn’t go through a three-way handshake to set up a connection—it simply begins sending the data. Likewise, UDP doesn’t check to see whether sent segments were received by a destination; in other words, it doesn’t use an acknowledgment

Some commonly used ports
Port Number Service
80 HTTP
21 FTP
110 POP3
25 SMTP
23 Telnet
FTP (File Transfer Protocol)

One of the earliest uses of the Internet, long before Web browsing came along, was transferring files between computers. The File Transfer Protocol (FTP) is used to connect to remote computers, list shared files, and either upload or download files between local and remote computers.

FTP runs over TCP, which provides a connection-oriented, guaranteed data-delivery service. FTP is a character-based command interface, although many FTP applications have graphical interfaces. FTP is still used for file transfer purposes, most commonly as a central FTP server with files available for download. Web browsers can make FTP requests to download programs from links selected on a Web page.

You should become familiar with the basic commands available in an FTP session. To begin a characterbased command session on a Windows computer, follow these steps.

  • Open a Command prompt window, type ftp at the prompt, and press Enter.
  • This will begin an FTP session on the local machine but will not initialize a connection to another machine.
  • Without a connection to another machine, you will not be able to do anything. To connect, type open example.com or open 10.10.10.1, in which exmple.com or 10.10.10.1 is the name or IP address of a host that is available as an FTP server. Most FTP servers require a logon id and password, or they will accept anonymous connections. At this point you will be prompted for a logon ID and password.
  • Once you are connected, you can list the files on the remote server by typing dir.
  • If you have create privileges on the remote server, you can create a new directory by typing mkdir.
  • To download a file, type get filename.txt where filename.txt is the name of the file you are downloading.
    To upload a file, typeput filename.txt.
SFTP (Secure File Transfer Protocol)

SSH File Transfer Protocol or SFTP is a network protocol that provides file transfer and manipulation functionality over any reliable data stream.

TFTP (Trivial File Transfer Protocol)

TFTP is used when a file transfer does not require an acknowledgment packet during file transfer. TFTP is used often in router configuration. TFTP is similar in operation to FTP. TFTP is also a command-line-based utility.

One of the two primary differences between TFTP and FTP is speed and authentication. Because TFTP is used without acknowledgment packets, it is usually faster than FTP. TFTP does not provide user authentication like FTP and therefore the user must be logged on to the client and the files on the remote computer must be writable. TFTP supports only unidirectional data transfer (unlike FTP, which supports bi-directional transfer). TFTP is operated over port 69.

SMTP (Simple Mail Transfer Protocol)

SMTP is a standard electronic-mail protocol that handles the sending of mail from one SMTP to another SMTP server. To accomplish the transport, the SMTP server has its own MX (mail exchanger) record in the DNS database that corresponds to the domain for which it is configured to receive mail.

When equipped for two-way communication, mail clients are configured with the address of a POP3 server to receive mail and the address of an SMTP server to send mail. The clients can configure server parameters in the properties sheets of the mail client, basing the choices on an FQDN or an IP address.

SMTP uses TCP for communication and operates on port 25. Simple Mail Transfer Protocol (SMTP) is the application-layer protocol used for transmitting e-mail messages. SMTP is capable of receiving e-mail messages, but it\’s limited in its capabilities. The most common implementations of SMTP are in conjunction with either POP3 or IMAP4. For example, users download an e-mail message from a POP3 server, and then transmit messages via an SMTP server

HTTP (Hypertext Transfer Protocol)

HTTP is often called the protocol of the Internet. HTTP received this designation because most Internet traffic is based on HTTP. When a user requests a Web resource, it is requested using HTTP. The following is a Web request:

http://www.example.com

When a client enters this address into a Web browser, DNS is called to resolve the Fully Qualified Domain Name (FQDN) to an IP address. When the address is resolved, an HTTP get request is sent to the Web server. The Web server responds with an HTTP send response. Such communication is done several times throughout a single session to a Web site. HTTP uses TCP for communication between clients and servers. HTTP operates on port 80.

HTTPS (Hypertext Transfer Protocol Secure)

HTTP is for Web sites using additional security features such as certificates. HTTPS is used when Web transactions are required to be secure. HTTPS uses a certificatebased technology such as VeriSign.

Certificate-based transactions offer a mutual authentication between the client and the server. Mutual authentication ensures the server of the client identity, and ensures the client of the server identity. HTTPS, in addition to using certificate-based authentication, encrypts all data packets sent during a session.

Because of the encryption, confidential user information cannot be compromised. To use HTTPS, a Web site must purchase a certificate from a third-party vendor such as VeriSign, CertCo, United States Postal Service, or other certificate providers. When the certificate is issued to a Web site from a third-party vendor, the Web site is using trusted communication with the client. The communication is trusted because the third party is not biased toward either the Web site or the client. To view a certificate during a HTTPS session, simply double-click the lock icon in the lower-right area of the Web browser. HTTPS operates on port 443 and uses TCP for communication.

POP3 / IMAP4 (Post Office Protocol version 3 / Internet Message Access Protocol version 4)

Post Office Protocol 3 (POP3) and Internet Message Access Protocol 4 (IMAP4) are two application-layer protocols used for electronic messaging across the Internet. POP3 is a protocol that involves both a server and a client. A POP3 server receives an e-mail message and holds it for the user. A POP3 client application periodically checks the mailbox on the server to download mail. POP3 does not allow a client to send mail, only to receive it. POP3 transfers e-mail messages over TCP port 110.

IMAP4 is an alternate e-mail protocol. IMAP4 works in the same way as POP3, in that an e-mail message is held on a server and then downloaded to an e-mail client application. Users can read their e-mail message locally in their e-mail client application, but they can\’t send an e-mail message using IMAP4. When users access e-mail messages via IMAP4, they have the option to view just the message header, including its title and the sender\’s name, before downloading the body of the message. Users can create, change, or delete folders on the server, as well as search for messages and delete them from the server.

To perform these functions, users must have continued access to the IMAP server while they are working with e-mail messages. With IMAP4, an e-mail message is copied from the server to the e-mail client. When a user deletes a message in the e-mail client, the message remains on the server until it is deleted on the server. POP3 works differently in that an e-mail message is downloaded and not maintained on the server, unless configured otherwise. Therefore, the difference between POP3 and IMAP4 is that IMAP4 acts like a remote file server, while POP3 acts in a store-and-forward manner in its default configuration. (You can configure POP3 clients to leave copies of messages on the server, if you prefer.)

Both Microsoft and Netscape Web browsers have incorporated POP3. In addition, the Eudora and Microsoft Outlook Express e-mail client applications support both POP3 and IMAP4.

Telnet

Short for Telecommunication Network, a virtual terminal protocol allowing a user logged on to one TCP/IP host to access other hosts on the network. Many people use remote control applications to access computers at their workplace from outside the network. In remote control, a session appears in which the user is able to manage the files on the remote computer, although the session appears to be functioning locally. Telnet is an early version of a remote control application.

Telnet is very basic; it offers solely character-based access to another computer. If you want to see a person\’s graphical desktop, you would need a different type of protocol, such as Remote Desktop Protocol (RDP), Independent Computing Architecture (ICA), or X Windows. Telnet acts as a user command with an underlying Transmission Control Protocol/Internet Protocol (TCP/IP) protocol that handles the establishment, maintenance, and termination of a remote session. The difference between using Telnet and a protocol such as File Transfer Protocol (FTP), is that Telnet logs you directly on to the remote host, and you see a window into that session on your local computer. A typical Telnet command might be as follows:

 telnet example.com

Because this particular host is invalid, this command will have no result. However, if it were a valid host the remote computer would ask you to log on with a user ID and password. A correct ID and password would allow you to log on and execute Telnet commands.

You can often use Telnet to manage equipment that lacks a monitor. For example, most routers have Telnet enabled so that the administrator can log in and manage the router. Telnet also provides a quick check to make certain that network connectivity is functioning. Because Telnet sits at the application layer, if it can connect to a remote host, you can be certain that network connectivity between the two hosts is operational, as well as all lower-layer protocols.

SSH (Secure Shell)

is a program for logging in to and executing commands on a remote machine. It provides secure encrypted communications between two untrusted hosts over an insecure network. X11 connections and arbitrary TCP/IP ports can also be forwarded over the secure channel. When SSH connects and logs in to a specified computer, the user must prove his/her identity to the remote machine which is transmitted across the connection using one of three forms of data encryption. This process makes SSH impervious to Internet eavesdroppers who might otherwise steal account information.

ICMP (Internet Control Message Protocol)

ICMP provides network diagnostic functions and error reporting. One of the most used IP commands is the Packet Internet Grouper (PING) command. When a host PINGS another client, it sends an ICMP ECHO request, and the receiving host responds with an ICMP ECHO REPLY. PING checks network connectivity on clients and routers. ICMP also provides a little network help for routers. When a router is being overloaded with route requests, the router sends a source quench message to all clients on the network, instructing them to slow their data requests to the router.

ARP / RARP (Address Resolution Protocol / Reverse Address Resolution Protocol)

The Address Resolution Protocol (ARP) is an Internet layer protocol that helps TCP/IP network components find other devices in the same broadcast domain. ARP uses a local broadcast (255.255.255.255) at layer 3 and FF:FF:FF:FF:FF:FF at layer 2 to discover neighboring devices. Basically stated, you have the IP address you want to reach, but you need a physical (MAC) address to send the frame to the destination at layer 2.

ARP resolves an IP address of a destination to the MAC address of the destination on the same data link layer medium, such as Ethernet. Remember that for two devices to talk to each other in Ethernet (as with most layer 2 technologies), the data link layer uses a physical address (MAC) to differentiate the machines on the segment. When Ethernet devices talk to each other at the data link layer, they need to know each other’s MAC addresses.

RARP is sort of the reverse of an ARP. In an ARP, the device knows the layer 3 address, but not the data link layer address. With a RARP, the device doesn’t have an IP address and wants to acquire one. The only address that this device has is a MAC address. Common protocols that use RARP are BOOTP and DHCP

NTP (Network Time Protocol)

The Network Time Protocol is used to synchronize the time of a computer client or server to another server or reference time source, such as a radio or satellite receiver or modem. It provides accuracy\’s typically within a millisecond on LANs and up to a few tens of milliseconds on WANs.

SNMP

SNMP is a two-way network management protocol. SNMP consists of two components, the SNMP Agent, and the SNMP Management Console. The SNMP Management Console is the server side for SNMP. The management console sends requests to the SNMP Agents as get commands that call for information about the client.

The SNMP Agent responds to the Management Console’s get request with a trap message. The trap message has the requested information for the Management Console to evaluate. Security can be provided in many ways with SNMP; however, the most common form of security for SNMP is the use of community names, associations that link SNMP Agents to their Management Consoles:

  • Agents, by default, respond only to Management Consoles that are part of the same community name.
  • If an SNMP Agent receives a request from a Management Console that is not part of the same community name, then the request for information is denied.

Because SNMP is an industry-standard protocol, heterogeneous environments are common. Many vendors provide versions of SNMP Management Consoles. Hewlett Packard, for example provides HP Open View (one of the most popular Management Consoles on the market); Microsoft provides SNMP Server with the Windows NT and 2000 Resource Kits and Systems Management Server. SNMP Management Consoles request information according to a Management Information Base (MIB) format. An MIB is a numeric value that specifies the type of request, and to which layer of the OSI model the request is being sent.

SCP (Secure Copy Protocol)

Secure Copy or SCP is a means of securely transferring computer files between a local and a remote host or between two remote hosts, using the Secure Shell (SSH) protocol. The protocol itself does not provide authentication and security; it expects the underlying protocol, SSH, to secure this.

The SCP protocol implements file transfers only. It does so by connecting to the host using SSH and there executes an SCP server (scp). The SCP server program is typically the very same program as the SCP client.

LDAP (Lightweight Directory Access Protocol)

Lightweight Directory Access Protocol, or LDAP, is a networking protocol for querying and modifying directory services running over TCP/IP.

A directory is a set of information with similar attributes organized in a logical and hierarchical manner. The most common example is the telephone directory, which consists of a series of names organized alphabetically, with an address and phone number attached.

An LDAP directory often reflects various political, geographic, and/or organizational boundaries, depending on the model chosen. LDAP deployments today tend to use Domain Name System (DNS) names for structuring the topmost levels of the hierarchy. Deeper inside the directory might appear entries representing people, organizational units, printers, documents, groups of people or anything else which represents a given tree entry.

IGMP (Internet Group Multicast Protocol)

The Internet Group Management Protocol is a communications protocol used to manage the membership of Internet Protocol multicast groups. IGMP is used by IP hosts and adjacent multicast routers to establish multicast group memberships. It is an integral part of the IP multicast specification, like ICMP for unicast connections. IGMP can be used for online video and gaming, and allows more efficient use of resources when supporting these uses.

LPR (Line Printer Remote)

The Line Printer Daemon protocol/Line Printer Remote protocol (or LPD, LPR) also known as the Berkeley printing system, is a set of programs that provide printer spooling and network print server functionality for Unix-like systems.

The most common implementations of LPD are the official BSD UNIX operating system and the LPRng project. The Common Unix Printing System (or CUPS), which is more common on modern Linux distributions, borrows heavily from LPD.

A printer that supports LPD/LPR is sometimes referred to as a \”TCP/IP printer\” (TCP/IP is used to establish connections between printers and workstations on a network), although that term seems equally applicable to a printer that supports CUPS.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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Network cable Crimping and Testing Tools

This tutorial explains the most common twisted-pair network cable testing and crimping tools in detail. Learn the tools that you can use to crimp and test twisted-pair network cables.

Cables are the backbone of a wired network. The stability, reliability, and performance of a wired network depend on cables. Installing and maintaining cables in a wired network is a difficult task.

To make this task easier, a variety of network cable crimping and testing tools are available. In this tutorial, we will not only discuss some of the most common network cable crimping and testing tools but also understand their features and functions.

Twisted-pair (STP and UTP) network cable crimping tools

Crimping tools are used for the following purposes.

  • To cut the network cable of the required length from the bundle.
  • To remove the outer and inner jackets of the network cable.
  • To attach the connectors on both ends of the cable.

Some crimping tools provide all the functionality while others provide one or two functionalities. The most common twisted-pair network cable crimping tools are described below.



Wire Cutter: – To cut the network cable of the required length from the bundle, you can use any standard wire cutter tool or can use a wire cutter tool that is specially designed for the twisted-pair cable. A twisted-pair wire cutter usually includes additional blades for stripping the wire.

Wire Stripper: – This tool is used to remove the outer and inner jackets of the network cable. Typically, you do not need to purchase this tool separately as all standard twisted-pair wire cutters are equipped with wire-strippers.

The following image shows two twisted-pair wire cutter tools equipped with wire-strippers.

wire cutter and wire stripper

Crimp tool: – This tool is used to attach the connectors to the cable. Typically, this tool also includes a wire-cutter and wire-stripper. So if you buy a crimp tool, you don\’t have to buy a wire-cutter and wire-striper separately.

The following image shows a crimping device equipped with a wire-stripper and wire-cutter.

crimping tool

Which tool you should buy depends on your requirements and budget. For example, if you want to install a dozen network cables, you can buy less expensive tools such as a low-cost wire stripper and a cheap crimp device. But if you are in a network cable setting up business or have a medium or large-sized network, you should buy a crimping tool that has a built-in a wire stripper and wire cutter. A high-quality twisted-pair cable crimping tool will cost you around $100 but will save you many headaches in the long run.

Network cable testing and troubleshooting tools



A network cable testing and troubleshooting tool is used for the following purposes.

  • To measure the length of a segment or network cable.
  • To detect loose connectors.
  • To identify an un-labeled network cable from all network cables.
  • To find a break in the network cable.
  • To certify the cable installation.

The following section describes the most common network cable testing and troubleshooting tools.

Cable certifier

This device thoroughly tests a network cable and certifies that the cable installation meets a special wiring standard such as Cat 5e, Cat 6, Cat 6a, and so forth. This device can check and test total segment length, crosstalk, noise, wiremap, resistance, impedance, and the capability to transfer data at the maximum frequency rated for the cable.

The following image shows a network cable certifier.

network cable certifier

Since this device performs a complete test and certifies the cable installation, it will cost you more than all the other test devices listed in this section. If you have a mid-size network or if you can buy this device, then you should always buy and use this device to manage network cables.

Basic cable tester

If you can\’t afford a network cable certifier, you can buy and use this device to manage your network cables. Besides certifying the cable installation, this device provides all remaining functionalities of a network cable certifier. It can test cable length, cross talk, and breaks in the cable. It can also check whether the connectors on both ends of a network cable are properly attached or not.

The following image shows a basic network cable tester tool.

basic network cable tester

Tone generator and the probe

This device is used to trace the unlabeled network cables. This device comes in two pieces: the tone generator and the probe. The tone generator generates tones or signals and places them on the network cable. The probe detects these signals on the other end of the cable.

You can use this tool to identify network cables that run from a central location to remote locations. For example, if you are working on a patch-panel or switch and trying to figure out which network cable connects back to an end-device (such as a PC), then you can use this device.

Place a tone generator at one end of the connection (end-device), and use the probe on another side (switch or patch-panel) to determine which network cable the tone generator is connected to.

The following image shows an example of a tone generator and probe.

tone generator and probe

Time domain reflectometer

This device is used to measure the length of a network cable as well as the breaks in the cable. This device transmits a signal on one end and measures the time the signal takes to reach the end of the cable. You can also use this device to find breaks in the cable. For example, this device can tell you approximately how far the break is located in the cable.

The following image shows a time domain reflectometer.

tdr

That’s all for this tutorial. If you like this tutorial, please don’t forget to share this tutorial with friends through your favorite social network.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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How DHCP Server works Explained with Examples

This tutorial explains basic concepts of DHCP Server including how DHCP Server assigns automatic IP address through four states (DHCP discovery, DHCP offer, DHCP request and DHCP acknowledgement). Learn what DHCP server is and how it works in network.

Computers on a IP networks need some essentials information before it can communicate with other hosts. This information include an IP address, and a default route and routing prefix. Configuring IP addressing on a large TCP/IP-based network can be a nightmare, especially if machines are moved from one network to another frequently. DHCP eliminates the manual task by a network administrator. The Dynamic Host Configuration Protocol (DHCP) can help with the workload of configuring systems on a network by assigning addresses to systems on boot-up automatically. It also provides a central database of devices that are connected to the network and eliminates duplicate resource assignments.

DHCP server may have three methods of allocating IP-addresses:

static allocation: The DHCP server allocates an IP address based on a table with MAC address/IP address pairs, which are manually filled Only requesting clients with a MAC address listed in this table will be allocated an IP address.

dynamic allocation: A network administrator assigns a range of IP addresses to DHCP, and each client computer on the LAN is configured to request an IP address from the DHCP server during network initialization.

automatic allocation: The DHCP server permanently assigns a free IP address to a requesting client from the range defined by the administrator. This is like dynamic allocation, but the DHCP server keeps a table of past IP address assignments, so that it can preferentially assign to a client the same IP address that the client previously had.

Among these three method static and dynamic method are the most popular implementation.

How DHCP work

DHCP provides an automated way to distribute and update IP addresses and other configuration information on a network. A DHCP server provides this information to a DHCP client through the exchange of a series of messages, known as the DHCP conversation or the DHCP transaction.

DHCP discovery

The client computers broadcasts messages on the physical subnet to discover available DHCP servers. This client-computers creates a User Datagram Protocol (UDP) packet with the default broadcast destination of 255.255.255.255 or the specific subnet broadcast address if any configured.

DHCP offer

When a DHCP server receives an IP lease request from a client, it reserves an IP address for the client and extends an IP lease offer by sending a DHCPOFFER message to the client. This message contains the client\’s MAC address, the IP address that the server is offering, the subnet mask, the lease duration, and the IP address of the DHCP server making the offer.

DHCP request

In most companies, two DHCP servers provide fault tolerance of IP addressing if one server fails or must be taken offline for maintenance. So client could receive DHCP offers from multiple servers, but it will accept only one DHCP offer. In response to the offer Client requests the server. The client replies DHCP Request, unicast to the server, requesting the offered address. Based on the Transaction ID field in the request, servers are informed whose offer the client has accepted. When other DHCP servers receive this message, they withdraw any offers that they might have made to the client and return the offered address to the pool of available addresses. In some cases DHCP request message is broadcast, instead of being unicast to a particular DHCP server, because the DHCP client has still not received an IP address. Also, this way one message can let all other DHCP servers know that another server will be supplying the IP address without missing any of the servers with a series of unicast messages.

DHCP acknowledgement

When the DHCP server receives the DHCPREQUEST message from the client, the configuration process enters its final phase.

The acknowledgement phase involves sending a DHCPACK packet to the client. This packet includes the lease duration and any other configuration information that the client might have requested. At this point, the IP configuration process is completed.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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How to configure IPv6 address in Windows

This tutorial explains how to configure IPv6 address in Windows system from command prompt as well as from GUI interface including Stateful and Stateless Autoconfiguration process and states (Tentative, Valid, Preferred, Deprecated and Invalid) in detail with examples.

Autoconfiguration is an incredibly useful solution because it allows devices on a network to address themselves with a link-local unicast address

Types of Autoconfiguration

There are three types of autoconfiguration:

  • Stateless Configuration of addresses and other settings is based on the receipt of Router Advertisement messages. These messages have the Managed Address Configuration and Other Stateful Configuration flags set to 0, and they include one or more Prefix Information options, each with its Autonomous flag set to 1.
  • Stateful Configuration is based on the use of an address configuration protocol, such as DHCPv6, to obtain addresses and other configuration settings. A host uses stateful autoconfiguration when it receives a Router Advertisement message with no Prefix Information options and either the Managed Address Configuration flag or the Other Stateful Configuration flag is set to 1. A host can also use stateful autoconfiguration when there are no routers present on the local link.
  • Both Configurations is based on the receipt of Router Advertisement messages that include Prefix Information options, each with its Autonomous flag set to 1, and have the Managed Address Configuration or Other Stateful Configuration flags set to 1. For all types of autoconfiguration, a link-local address is always configured automatically.

Stateful Configuration

The client detects a router; the client examines the router advertisement messages to determine whether DHCPv6 has been set up. If the router specifies that DHCPv6 is supported, or no router advertisement messages are seen, the client will begin to find a DHCPv6 server by generating a DHCP solicit message. This message is sent to the ALL-DHCP-Agents multicast address, using the link-local scope to ensure the message isn’t forwarded, by default, beyond the local link. An agent is either a DHCPv6 server or a relay, such as a router.

Stateless Autoconfiguration

Stateless autoconfiguration is an extension of DHCPv6. the client uses information in router advertisement messages to configure an IPv6 address for the interface. This is accomplished by taking the first 64 bits in the router advertisement source address (the prefix of the router’s address) and using the EUI-64 process to create the 64-bit interface ID. Stateless autoconfiguration was designed primarily for cell phones, PDAs, and home network and appliance equipment to assign addresses automatically without having to manage a DHCP server infrastructure. Normally, routers generate periodic router advertisement (RA) messages the client can listen to and then use to generate its link address automatically; however, when the client is booting up, waiting for the RA might take awhile. In this situation, the client will generate a router solicitation message, asking the router to reply with an RA so the client can generate its interface address.

Two steps to IPv6 autoconfiguration



Autoconfigured Address States

Autoconfigured addresses are in one or more of the following states:

  • Tentative The address is in the process of being verified as unique. Verification occurs through duplicate address detection. A node cannot receive unicast traffic to a tentative address. It can, however, receive and process multicast Neighbor Advertisement messages sent in response to the Neighbor Solicitation message that has been sent during duplicate address detection.
  • Valid The address can be used for sending and receiving unicast traffic. The valid state includes both the preferred and deprecated states. The sum of the times that an address remains in the tentative, preferred, and deprecated states is determined by the Valid Lifetime field in the Prefix Information option of a Router Advertisement message or the Valid-Lifetime field of a DHCPv6 IA (Identity Association) Address option.
  • Preferred The address is valid, its uniqueness has been verified, and it can be used for unlimited communications. A node can send and receive unicast traffic to and from a preferred address. The period of time that an address can remain in the tentative and preferred states is determined by the Preferred Lifetime field in the Prefix Information option of a Router Advertisement message or the Preferred-Lifetime field of a DHCPv6 IA Address option.
  • Deprecated The address is valid and its uniqueness has been verified, but its use is discouraged for new communication. Existing communication sessions can still use a deprecated address. A node can send and receive unicast traffic to and from a deprecated address.
  • Invalid The address can no longer be used to send or receive unicast traffic. An address enters the invalid state after the valid lifetime expires.

Autoconfiguration Process

The address autoconfiguration process defined in RFC 4862 for the physical interface of an IPv6 node is the following:

  • A tentative link-local address is derived based on the link-local prefix of FE80::/64 and a EUI-64–derived interface identifier.
  • Using duplicate address detection to verify the uniqueness of the tentative link-local address, a Neighbor Solicitation message is sent with the Target Address field that is set to the tentative link-local address.
  • If a Neighbor Advertisement message (sent in response to the Neighbor Solicitation message) is received, this indicates that another node on the local link is using the tentative link-local address and address autoconfiguration stops. At this point, manual configuration must be performed on the node.
  • If no Neighbor Advertisement message (sent in response to the Neighbor Solicitation message) is received, the tentative link-local address is assumed to be unique and valid. The link-local address is initialized for the interface. The link-layer multicast address of the solicited-node address corresponding to the link-local address is registered with the network adapter.



For an IPv6 host, the address autoconfiguration continues as follows:

  • The host sends a Router Solicitation message. While routers periodically send router advertisements, the host sends a Router Solicitation message to request an immediate router advertisement, rather than waiting until the next router advertisement. By default, up to three Router Solicitation messages are sent.
  • If no Router Advertisement messages are received, the host uses an address configuration protocol to obtain addresses and other configuration parameters.
  • If a Router Advertisement message is received, the hop limit, reachable time, retransmission timer, and maximum transmission unit (if that option is present) are set.
  • For each Prefix Information option present, the following actions occur:
  • If the On-Link flag is set to 1, the prefix is added to the prefix list.
  • If the Autonomous flag is set to 1, the prefix and an appropriate interface identifier are used to derive a tentative address.
  • Duplicate address detection is used to verify the uniqueness of the tentative address.
  • If the tentative address is in use, the use of the address is not initialized for the interface.
  • If the tentative address is not in use, the address is initialized. This includes setting the valid and preferred lifetimes based on the Valid Lifetime and Preferred Lifetime fields in the Prefix Information option. If needed, it also includes registering the link-layer multicast address of the solicited-node address corresponding to the new address with the network adapter.
  • If the Managed Address Configuration flag in the Router Advertisement message is set to 1, an address configuration protocol is used to obtain additional addresses.
  • If the Other Stateful Configuration flag in the Router Advertisement message is set to 1, an address configuration protocol is used to obtain additional configuration parameters.

The following are the specific autoconfiguration behaviors of IPv6 in Windows Server 2008 and Windows Vista:

  • Computers running Windows Server 2008 or Windows Vista by default generate random interface IDs for non-temporary autoconfigured IPv6 addresses, including public and link-local addresses, rather than using EUI-64–based interface IDs.
    A public IPv6 address is a global address that is registered in DNS and is typically used by server applications for incoming connections, such as a Web server.
    You can disable this default behavior with the
    netsh interface ipv6 set global randomizeidentifiers=disabled
    command. You can enable the default behavior with the
    netsh interface ipv6 set global randomizeidentifiers=enabled command.
  • With a randomly derived interface ID, the chance of duplicating the link-local address is very small. Therefore, computers running Windows Server 2008 or Windows Vista do not wait for duplicate address detection (DAD) to complete before sending router solicitations or multicast listener discovery reports using their derived link-local addresses. This is known as optimistic DAD.
  • Computers running Windows Server 2008 or Windows Vista do not attempt stateful address autoconfiguration with DHCPv6 if no router advertisements are received.
  • RFC 4862 does not require a specific order for sending the initial router solicitation and performing duplicate address detection for the derived link-local address. The IPv6 protocol for Windows Server 2008 and Windows Vista sends the Router Solicitation message before performing duplicate address detection on the link-local address. In this way, duplicate address detection and router discovery are done in parallel to save time during the interface initialization process.
  • If the derived link-local address is a duplicate, stateless address autoconfiguration for the IPv6 protocol for Windows Server 2008 and Windows Vista can continue with the receipt of a multicast Router Advertisement message containing site-local, unique local, or global prefixes. The attempted link-local address is shown with a “Duplicate” state in the display of the
    netsh interface ipv6 show address
    command and a site-local, unique local, or global address—rather than the duplicate link-local address—is used for neighbor discovery processes.

Autoconfigured Addresses for the IPv6 Protocol for Windows Server 2008 and Windows Vista

By default, the following IPv6 addresses are automatically configured for the IPv6 protocol for Windows Server 2008 and Windows Vista:

  • Link-local addresses using randomly derived interface identifiers are assigned to all local area network (LAN) interfaces.
  • If included as a site-local prefix in a Prefix Information option of a router advertisement with the Autonomous flag set to 1, a site-local address using a randomly derived interface identifier is assigned to the LAN interface that received the router advertisement.
  • If included as a global or unique local prefix in a Prefix Information option of a router advertisement with the Autonomous flag set to 1, a global or unique local address using a randomly derived permanent interface identifier is assigned to the LAN interface that received the router advertisement.
  • If included as a global or unique local prefix in a Prefix Information option of a router advertisement with the Autonomous flag set to 1, a temporary global or unique local address using a randomly derived temporary interface identifier is assigned to the LAN interface that received the router advertisement. This is the default behavior for Windows Vista. Window Server 2008 does not create temporary addresses by default. You can enable temporary addresses with the netsh interface ipv6 set privacy enabled command.
  • If the M flag is set to 1 in a received Router Advertisement message, a stateful IPv6 address based on DHCPv6 scope for the subnet is assigned to the LAN interface that received the DHCPv6 Reply message.
  • If public IPv4 addresses are assigned to interfaces of the computer and there are no global or unique local autoconfiguration prefixes received in Router Advertisement messages, corresponding 6to4 addresses using 6to4-derived interface identifiers are assigned to the 6to4 tunneling interface. 6to4 is described in RFC 3056.
  • For computers running Windows Vista, for all IPv4 addresses that are assigned to interfaces of the computer, corresponding link-local addresses using Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)–derived interface identifiers (::0:5EFE:w.x.y.z or ::200:5EFE:w.x.y.z) are assigned to the ISATAP tunneling interface. ISATAP is described in RFC 4214.
  • If included as a global, unique local, or site-local prefix in a Prefix Information option of a router advertisement received on the ISATAP interface, a global, unique local, or site local address using the ISATAP-derived interface identifier corresponding to the IPv4 address that is the best source to use to reach the ISATAP router is assigned to the ISATAP interface.
  • The loopback address (::1) is assigned to the Loopback Pseudo-Interface 1.

Manually IPv6 Configuration in Windows

One option you have is to statically assign a unicast address to a device’s interface using either of these two approaches:
Specify all 128-bits manually
Use EUI-64

You can manually specify the entire 128-bit address, or you can specify the subnet ID and have the device use the EUI-64 method to create the interface ID part of the address

Manually Configuring the IPv6 Protocol

Unlike IPv6 in Windows XP and Windows Server 2003, the IPv6 protocol in Windows Server 2008 and Windows Vista is installed and enabled by default. The IPv6 protocol for Windows Server 2008 and Windows Vista is designed to be auto configuring. For example, it automatically configures link-local addresses for communication between nodes on a link. If there is an IPv6 router on the host’s subnet or an ISATAP router, the host uses received router advertisements to automatically configure additional addresses, a default router, and other configuration parameters. You can manually configure IPv6 addresses and other parameters in Windows Vista using the following:

  • Form lan card properties
  • From command prompt

The properties of Internet Protocol Version 6 (TCP/IPv6) component

Just as you can configure IPv4 settings through the properties of the Internet Protocol Version 4 (TCP/IPv4) component in the Network Connections folder, you can now configure IPv6 settings through the properties of the Internet Protocol Version 6 (TCP/IPv6) component. The set of dialog boxes for IPv6 configuration is very similar to the corresponding dialog boxes for IPv4. However, the properties of the Internet Protocol Version 6 (TCP/IPv6) component provide only basic configuration of IPv6.

Commands in the netsh interface ipv6 context

Just as you can in Windows XP and Windows Server 2003, you can configure IPv6 settings for Windows Server 2008 or Windows Vista from the interface ipv6 context of the Netsh.exe tool. Although typical IPv6 hosts do not need to be manually configured, IPv6 routers must be manually configured.

Configuring IPv6 Through the Properties of Internet Protocol Version 6 (TCP/IPv6)
To manually configure IPv6 settings through the Network Connections folder, do the following:

  • From the Network Connections folder, right-click the connection or adapter on which you want to manually configure IPv6, and then click Properties.
  • On the Networking tab for the properties of the connection or adapter, under This Connection Uses The Following Items, double-click Internet Protocol Version 6 (TCP/IPv6) in the list.

Windows Vista displays the Internet Protocol Version 6 (TCP/IPv6) Properties dialog box.

The Internet Protocol Version 6 (TCP/IPv6) Properties dialog box

How to configure IPv6 address in Windows

General Tab

On the General tab of the Internet Protocol Version 6 (TCP/IPv6) Properties dialog box, you can configure the following:

  • Obtain an IPv6 address automatically Specifies that IPv6 addresses for this connection or adapter are automatically determined by stateful or stateless address autoconfiguration.
  • Use the following IPv6 address< Specifies that an IPv6 address and default gateway for this connection or adapter are manually configured.
  • IPv6 address Provides a space for you to type an IPv6 unicast address. You can specify additional IPv6 addresses from the Advanced TCP/IP Settings dialog box.
  • Subnet prefix length Provides a space for you to type the subnet prefix length for the IPv6 address. For typical IPv6 unicast addresses, this value should be set to 64, its default value.
  • Default gateway Provides a space for you to type the IPv6 unicast address of the default gateway.
  • Obtain DNS server address automatically Specifies that the IPv6 addresses for DNS servers are automatically determined by stateful address autoconfiguration (DHCPv6).
  • Use the following DNS server addresses Specifies that the IPv6 addresses of the preferred and alternate DNS servers for this connection or adapter are manually configured.
  • Preferred DNS server Provides a space for you to type the IPv6 unicast address of the preferred DNS server.
  • Alternate DNS server Provides a space for you to type the IPv6 unicast address of the alternate DNS server. You can specify additional DNS servers from the Advanced TCP/IP Settings dialog box.

Advanced TCP/IP Settings

From the General tab, you can click Advanced to access the Advanced TCP/IP Settings dialog box. This dialog box is very similar to the Advanced TCP/IP Settings dialog box for the Internet Protocol Version 4 (TCP/IPv4) component except there is no WINS tab (IPv6 does not use NetBIOS and the Windows Internet Name Service [WINS]) or Options tab (TCP/IP filtering is defined only for IPv4 traffic). For IPv6, the Advanced TCP/IP Settings dialog box has IP Settings and DNS tabs.

configure IPv6 address in Windows advance tab

The IP Settings tab

From the IP Settings tab, you can configure the following:

  • Multiple IPv6 addresses (by clicking Add under IP Addresses) For each unicast IPv6 address, you must specify an IPv6 address and a subnet prefix length. The Add button is available only if Use The Following Ipv6 Address has been selected on the General tab of the Internet Protocol Version 6 (TCP/IPv6) Properties dialog box.
  • Multiple default gateways (by clicking Add under Default Gateways) For each default gateway, you must specify the IPv6 address of the gateway and whether you want the metric for the default route associated with this default gateway to be manually specified or based on the speed of the connection or adapter.
  • Route metrics You can also specify whether to use a specific metric for the routes associated with the configuration of IPv6 addresses or default gateways or a metric determined by the speed of the connection or adapter.

The DNS tab

From the DNS tab, you can configure the following:

  • The IPv6 addresses of DNS servers, in order of use (by clicking Add under DNS Server Addresses, In Order Of Use).
  • Primary and connection-specific DNS suffix and name registration and devolution behavior. These settings are the same as for IPv4.

Configuring IPv6 with the Netsh.exe Tool

You can also configure IPv6 addresses, default gateways, and DNS servers at the command line using commands in the netsh interface ipv6 context.

Configuring Addresses

To configure IPv6 addresses, you can use the netsh interface ipv6 add address command with the following syntax:

netsh interface ipv6 add address [interface=]InterfaceNameorIndex [address=]IPv6Address
[/PrefixLength] [[type=]unicast|anycast] [[validlifetime=]Time|infinite] [[preferredlifetime=]
Time|infinite] [[store=]active|persistent]
  • interface The connection or adapter’s name or interface index.
  • address The IPv6 address to add, optionally followed by the subnet prefix length (default of 64).
  • type The type of IPv6 address, either unicast (default) or anycast.
  • validlifetime The lifetime over which the address is valid. Time values can be expressed in days, hours, minutes, and seconds (for example, 1d2h3m4s). The default value is infinite.
  • preferredlifetime The lifetime over which the address is preferred. Time values can be expressed in days, hours, minutes, and seconds. The default value is infinite.
  • store How to store the IPv6 address—either active (the address is removed upon system restart) or persistent (address remains after system restart), which is the default.

For example, to configure the IPv6 unicast address 2001:db8:290c:1291::1 on the interface named “Local Area Connection” with infinite valid and preferred lifetimes and make the address persistent, you use the following command:

netsh interface ipv6 add address \"Local Area Connection\" 2001:db8:290c:1291::1

Adding Default Gateways

To configure a default gateway, you can use the netsh interface ipv6 add route command and add a default route (::/0) with the following syntax:

netsh interface ipv6 add route [prefix=]::/0 [interface=]InterfaceNameorIndex
[[nexthop=]IPv6Address] [[siteprefixlength=]Length] [[metric=]MetricValue] [[publish=]
no|yes|immortal] [[validlifetime=]Time|infinite] [[preferredlifetime=]Time|infinite]
[[store=]active|persistent]
  • prefix The IPv6 address prefix and prefix length for the default route. For other routes, you can substitute ::/0 with AddressPrefix/PrefixLength.
  • interface The connection or adapter’s name or interface index.
  • nexthop If the prefix is for destinations that are not on the local link, the next-hop IPv6 address of a neighboring router.
  • siteprefixlength If the prefix is for destinations on the local link, you can optionally specify the prefix length for the address prefix assigned to the site to which this IPv6 node belongs.
  • metric A value that specifies the preference for using the route. Lower values are preferred.
  • publish As an IPv6 router, this option specifies whether the subnet prefix corresponding to the route will be included in router advertisements and whether the lifetimes for the prefixes are infinite (the immortal option).
  • validlifetime The lifetime over which the route is valid. Time values can be expressed in days, hours, minutes, and seconds (for example, 1d2h3m4s). The default value is infinite.
  • preferredlifetime The lifetime over which the route is preferred. Time values can be expressed in days, hours, minutes, and seconds. The default value is infinite.
  • store How to store the route, either active (route is removed upon system restart) or persistent (route remains after restart), which is the default.

For example, to add a default route that uses the interface named “Local Area Connection” with a next-hop address of fe80::2aa:ff:fe9a:21b8 you use the following command:

netsh interface ipv6 add route ::/0 \"Local Area Connection\" fe80::2aa:ff:fe9a:21b8

Adding DNS Servers

To configure the IPv6 addresses of DNS servers, you can use the netsh interface ipv6 add dnsserver command with the following syntax:

netsh interface ipv6 add dnsserver [name=]InterfaceName [[address=]IPv6Address]
[[index=]PreferenceValue]
  • name The connection or adapter’s name.
  • address The IPv6 address of the DNS server.
  • index The preference for the DNS server address.

By default, the DNS server is added to the end of the list of DNS servers. If an index is specified, the DNS server is placed in that position in the list and the other DNS servers are moved down the list.

For example, to add a DNS server with the IPv6 address 2001:db8:99:4acd::8 that uses the interface named “Local Area Connection,” you use the following command:

 netsh interface ipv6 add dnsserver \"Local Area Connection\" 2001:db8:99:4acd::8
 

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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Networking Tutorials

Network Cable Connectors Types and Specifications

This tutorial explains network cable connector types and specifications in details. Learn what type of network cable connector (such as Rj-45, J Rj-11, USB, MT-RJ, Coaxial BNC, LC Local Connector, MT-RJ, USB BNC and AUI) is used to connect what type of network cable.

USB (Universal Serial Bus)

Universal Serial Bus, or USB, is a computer standard designed to eliminate the guesswork in connecting peripherals to a PC. It is expected to replace serial and parallel ports. A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, keyboards, digital camera\’s, printers, scanners, MP3 players and many more. USB also supports Plug-and-Play installation and hot plugging.

  • USB 1.1 standard supports data transfer rates of 12 Mbps.
  • USB 2.0 (Also referred to as Hi-Speed USB) specification defines a new High-speed transfer rate of 480 Mb/sec.

USB 2.0 is fully compatible with USB 1.1 and uses the same cables and connectors. USB has with two connector types. The first is Type A (on the right), This connector connects to the PC\’s USB port. The Type B (on the left) connector and is for connecting to the relevant peripheral. Where as the type A connector is truly standard, the Type B connector could be changed in size etc. with individual peripherals meaning they require there own unique cables.

RJ-11 (Registered Jack)

Standard telephone cable connectors, RJ-11 has 4 wires (and RJ-12 has 6 wires). RJ-11 is the acronym for Registered Jack-11, a four- or six-wire connector primarily used to connect telephone equipment.

Rj-11

RJ-11 Pin Signal Name
1 VCC (5 volts regulated)
2 Power Ground
3 One Wire Data
4 One Wire Ground

RJ-45 (Registered Jack)

The acronym for Registered Jack-45 is RJ-45. The RJ-45 connector is an eight-wire connector that is commonly used to connect computers to a local area network (LAN), particularly Ethernet LANs. Although they are slightly larger than the more commonly used RJ-11 connectors, RJ-45s can be used to connect some types of telephone equipment.

Rj-45

F-Type

The F connector is a type of RF connector commonly used for cable and universally for satellite television. They are also used for the cable TV connection in DOCSIS cable modems, usually with RG-6 tri-shield cable. The F connector is inexpensive, yet has good performance up to 1 GHz. One reason for its low cost is that it uses the center wire of the coaxial cable as the pin of the male connector. The male connector body is typically crimped onto the exposed outer braid. Female connectors have a 3/8-32 thread. Most male connectors have a matching threaded connecting ring, though push-on versions are also available.

F type connector

ST (Straight Tip) and SC (Subscriber Connector or Standard Connector)

Fiber network segments always require two fiber cables: one for transmitting data, and one for receiving. Each end of a fiber cable is fitted with a plug that can be inserted into a network adapter, hub, or switch. In the North America, most cables use a square SC connector (Subscriber Connector or Standard Connector) that slides and locks into place when inserted into a node or connected to another fiber cable, Europeans use a round ST connector (Straight Tip) instead.

SC connector

ScUniCam-Pretium-SM-Connectors_lg

ST connector

 ST connector

Fiber LC (Local Connector)

These connectors are used for single-mode and multimode fiber-optic cables. FC connectors offer extremely precise positioning of the fiber-optic cable with respect to the transmitter\’s optical source emitter and the receiver\’s optical detector. FC connectors feature a position locatable notch and a threaded receptacle.

Fiber Lc Local

MT-RJ (Mechanical Transfer Registered Jack)

MT-RJ connectors are used with single-mode and multimode fiber-optic cables. The MT-RJ connectors are constructed with a plastic housing and provide for accurate alignment via their metal guide pins and plastic ferrules.

Used for Gigabit ethernet. To connect to modules with MT-RJinterfaces, use multimode fiber-optic cables.

MT-RJ

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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Network Cable Types and Specifications

This tutorial explains the types of network cables used in computer networks in detail. Learn the specifications, standards, and features of the coaxial cable, twisted-pair cable, and the fiber-optical cable.

To connect two or more computers or networking devices in a network, network cables are used. There are three types of network cables; coaxial, twisted-pair, and fiber-optic.

Coaxial cable

This cable contains a conductor, insulator, braiding, and sheath. The sheath covers the braiding, braiding covers the insulation, and the insulation covers the conductor.

The following image shows these components.

coaxial cable

Sheath

This is the outer layer of the coaxial cable. It protects the cable from physical damage.

Braided shield

This shield protects signals from external interference and noise. This shield is built from the same metal that is used to build the core.

Insulation

Insulation protects the core. It also keeps the core separate from the braided-shield. Since both the core and the braided-shield use the same metal, without this layer, they will touch each other and create a short-circuit in the wire.

Conductor

The conductor carries electromagnetic signals. Based on conductor a coaxial cable can be categorized into two types; single-core coaxial cable and multi-core coaxial cable.

A single-core coaxial cable uses a single central metal (usually copper) conductor, while a multi-core coaxial cable uses multiple thin strands of metal wires. The following image shows both types of cable.

single core and multi-core coaxial cable

Coaxial cables in computer networks



The coaxial cables were not primarily developed for the computer network. These cables were developed for general purposes. They were in use even before computer networks came into existence. They are still used even their use in computer networks has been completely discontinued.

At the beginning of computer networking, when there were no dedicated media cables available for computer networks, network administrators began using coaxial cables to build computer networks.

Because of low-cost and long durability, coaxial cables were used in computer networking for nearly two decades (80s and 90s). Coaxial cables are no longer used to build any type of computer network.

Specifications of coaxial cables

Coaxial cables have been in use for the last four decades. During these years, based on several factors such as the thickness of the sheath, the metal of the conductor, and the material used in insulation, hundreds of specifications have been created to specify the characteristics of coaxial cables.

From these specifications, only a few were used in computer networks. The following table lists them.

Type Ohms AWG Conductor Description
RG-6 75 18 Solid copper Used in cable network to provide cable Internet service and cable TV over long distances.
RG-8 50 10 Solid copper Used in the earliest computer networks. This cable was used as the backbone-cable in the bus topology. In Ethernet standards, this cable is documented as the 10base5 Thicknet cable.
RG-58 50 24 Several thin strands of copper This cable is thinner, easier to handle and install than the RG-8 cable. This cable was used to connect a system with the backbone-cable. In Ethernet standards, this cable is documented as the 10base2 Thinnet cable.
RG-59 75 20 – 22 Solid copper Used in cable networks to provide short-distance service.
  • Coaxial cable uses RG rating to measure the materials used in shielding and conducting cores.
  • RG stands for the Radio Guide. Coaxial cable mainly uses radio frequencies in transmission.
  • Impedance is the resistance that controls the signals. It is expressed in the ohms.
  • AWG stands for American Wire Gauge. It is used to measure the size of the core. The larger the AWG size, the smaller the diameter of the core wire.

Twisted-pair cables



The twisted-pair cable was primarily developed for computer networks. This cable is also known as Ethernet cable. Almost all modern LAN computer networks use this cable.

This cable consists of color-coded pairs of insulated copper wires. Every two wires are twisted around each other to form pair. Usually, there are four pairs. Each pair has one solid color and one stripped color wire. Solid colors are blue, brown, green and orange. In stripped color, the solid color is mixed with the white color.

Based on how pairs are stripped in the plastic sheath, there are two types of twisted-pair cable; UTP and STP.

In the UTP (Unshielded twisted-pair) cable, all pairs are wrapped in a single plastic sheath.

In the STP (Shielded twisted-pair) cable, each pair is wrapped with an additional metal shield, then all pairs are wrapped in a single outer plastic sheath.

Similarities and differences between STP and UTP cables

  • Both STP and UTP can transmit data at 10Mbps, 100Mbps, 1Gbps, and 10Gbps.
  • Since the STP cable contains more materials, it is more expensive than the UTP cable.
  • Both cables use the same RJ-45 (registered jack) modular connectors.
  • The STP provides more noise and EMI resistant than the UTP cable.
  • The maximum segment length for both cables is 100 meters or 328 feet.
  • Both cables can accommodate a maximum of 1024 nodes in each segment.

The following image shows both types of twisted-pair cable.

STP UTP cable

To learn how twisted-pair cables are used in the LAN network, you can check this tutorial.

Twisted-pair cabling

This tutorial explains how the twisted-pair cable works and how it is used to connect different networking devices in a network.

The TIA/EIA specifies standards for the twisted-pair cable. First standards were released in 1991, known as TIA/EIA 568. Since then, these standards have been continually revised to cover the latest technologies and developments of the transmission media.

The TIA/EIA 568 divides the twisted-pair cable into several categories. The following table lists the most common and popular categories of the twisted-pair cable.

Category / name of the cable Maximum supported speed Bandwidth/support signals rate Ethernet standard Description
Cat 1 1Mbps 1MHz Not used for data This cable contains only two pairs (4 wires). This cable was used in the telephone network for voice transmission.
Cat 2 4Mbps 10MHz Token Ring This cable and all further cables have a minimum of 8 wires (4 pairs). This cable was used in the token-ring network.
Cat 3 10Mbps 16MHz 10BASE-T Ethernet This is the first Ethernet cable that was used in LAN networks.
Cat 4 20Mbps 20MHz Token Ring This cable was used in advanced Token-ring networks.
Cat 5 100Mbps 100MHz 100BASE-T Ethernet This cable was used in advanced (fast) LAN networks.
Cat 5e 1000Mbps 100MHz 1000BASE-T Ethernet This cable/category is the minimum requirement for all modern LAN networks.
Cat 6 10Gbps 250MHz 10GBASE-T Ethernet This cable uses a plastic core to prevent cross-talk between twisted-pair. It also uses a fire-resistant plastic sheath.
Cat 6a 10Gbps 500MHz 10GBASE-T Ethernet This cable reduces attenuation and cross-talk. This cable also potentially removes the length limit. This is the recommended cable for all modern Ethernet LAN networks.
Cat 7 10Gbps 600MHz Not drafted yet This cable sets a base for further development. This cable uses multiple twisted-pairs and shields each pair by its own plastic sheath.
  • Cat 1, 2, 3, 4, 5 are outdated and not used in any modern LAN network.
  • Cat 7 is still a new technology and not commonly used.
  • Cat 5e, 6, 6a are the commonly used twisted-pair cables.

Fiber optic cable

This cable consists of core, cladding, buffer, and jacket. The core is made from the thin strands of glass or plastic that can carry data over the long distance. The core is wrapped in the cladding; the cladding is wrapped in the buffer, and the buffer is wrapped in the jacket.

  • Core carries the data signals in the form of the light.
  • Cladding reflects light back to the core.
  • Buffer protects the light from leaking.
  • The jacket protects the cable from physical damage.

Fiber optic cable is completely immune to EMI and RFI. This cable can transmit data over a long distance at the highest speed. It can transmit data up to 40 kilometers at the speed of 100Gbps.

Fiber optic uses light to send data. It reflects light from one endpoint to another. Based on how many beams of light are transmitted at a given time, there are two types of fiber optical cable; SMF and MMF.

SMF MMF Fiber optical cable

SMF (Single-mode fiber) optical cable

This cable carries only a single beam of light. This is more reliable and supports much higher bandwidth and longer distances than the MMF cable. This cable uses a laser as the light source and transmits 1300 or 1550 nano-meter wavelengths of light.

MMF (multi-mode fiber) optical cable

This cable carries multiple beams of light. Because of multiple beams, this cable carries much more data than the SMF cable. This cable is used in shorter distances. This cable uses an LED as the light source and transmits 850 or 1300 nano-meter wavelengths of light.

That’s all for this tutorial. In the next part of this article, we will understand the types of connectors that are used to connect cables with networking devices. If you like this tutorial, please don’t forget to share it with friends through your favorite social channel.

Prerequisites for 200-301

200-301 is a single exam, consisting of about 120 questions. It covers a wide range of topics, such as routing and switching, security, wireless networking, and even some programming concepts. As with other Cisco certifications, you can take it at any of the Pearson VUE certification centers.

The recommended training program that can be taken at a Cisco academy is called Implementing and Administering Cisco Solutions (CCNA). The successful completion of a training course will get you a training badge.

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