This tutorial explains the types of routes and types of routing. Learn what the static route and dynamic route are and how these routes are discovered by a router through static routing and dynamic routing.
To forward incoming data packets, a router learns all available routes in the network and stores them in a table known as the routing table. There are two types of routes: static route and dynamic route. A router can learn these routes through two types of routing: static routing and dynamic routing, respectively.
A static route is a route that is either directly configured on an active interface of the router or manually added in the routing table by an administrator. When we configure an IP address on an interface of a router, the router automatically determines the corresponding network address and adds that network address in the routing table.
A dynamic route is a route that is neither directly configured on an active interface of the router nor manually added in the routing table by an administrator. A router learns dynamic routes by running a routing protocol. Since a router learns dynamic routes through a routing protocol, a routing protocol must be configured and activated before the router can learn any dynamic routes.
Let’s take an example. In a network, two routers: router0 and router1 are connected through a serial cable. To connect both routers, the network 184.108.40.206/8 is used on serial interfaces. Network 10.0.0.0/8 is connected to the router0 and the network 220.127.116.11/8 is connected to the router1.
The following table shows the IP configuration of both routers.
|Interface||IP address||Interface||IP address|
|FastEthernet 0/0||10.10.10.1/8||FastEthernet 0/0||18.104.22.168/8|
|Serial 0/0/0||22.214.171.124/8||Serial 0/0/0||126.96.36.199/8|
When we activate an interface of a router, the router does the following:
- Read the IP configuration of the interface.
- Extract network information from the IP configuration.
- Find the extracted network information in the routing table.
- If the routing table already contains an entry for the extracted network, the router updates that entry.
- If the routing table contains no entry for the extracted network, the router adds an entry for the extracted network.
The following image shows how the router0 learns the network address from the IP configuration of the FastEthernet 0/0 interface and adds that network address in the routing table.
A router can, on its own, only learn networks that are directly connected to its active interfaces. In other words, through the above-described process, a router can discover only those network paths that are directly available on its interfaces. If a network is available on the interface of another router, a router cannot learn that network on its own.
The following image shows how both routers learn and add network paths from IP configurations.
As you can see in the above image, a router neither can learn nor can populate the routing table with the networks that are not available on its interfaces. A router uses the routing table to make the packet forwarding decision.
If a router does not have an entry for a path in the routing table, it drops the incoming packets of that network.
A router can learn about the paths that are not available on its interfaces through two types of routing; static routing and dynamic routing.
In the static routing, we have to add the remote paths manually. In the dynamic routing, we configure a routing protocol and later the routing protocol automatically discovers the remote paths and adds them into the routing table.
The following image shows both types of routing in our example network.
Both types of routing have their advantages and disadvantages. The advantages of one type of routing are the disadvantages of the other types of routing.
The following table compares both types of routing with their advantages and disadvantages.
|Static Routing||Dynamic Routing|
|Do not require any additional knowledge.||Require knowledge of the routing protocol that will be used in the network.|
|Any change in the path information requires a manual update on all routers.||If the path information changes, the routing protocol automatically updates all routers.|
|Since routes are configured manually, the static routing is considered more secure than the dynamic routing.||Since routers learn routes from the routing protocol, the dynamic routing is considered less secure than the static routing.|
|Do not use any additional hardware resources.||Consume CPU, memory and link bandwidth.|
Which type of routing an administrator should use is depend on the size and requirement of the network. If the network is small and has only a few paths, an administrator can use static routing to save hardware resources. If the network is large and complex, an administrator can use dynamic routing to reduce the tedious job of managing paths manually.
That’s all for this tutorial. If you like this tutorial, please don’t forget to share it 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.
Full Version 200-301 Dumps