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Computer network re-design from static to dynamic routing

You have been tasked with reconfiguring the network for your company, which has grown considerably over the past year. You have used only static routing in the past, but you do not wish to spend the administrative time required to maintain the routing tables now that the network has grown. You have recently experienced numerous inaccuracies in the routing table caused by entries you made when in a hurry.

Criteria for the reconfiguration includes the following:
-You would like to automate the entry and updating of routing information, but you are concerned about excessive memory and processor utilization if you implement dynamic routing protocols.
-You also wish to minimize the use of network bandwidth.
-You prefer that the most efficient use of bandwidth be made so that packets will travel to their destination over the truly shortest path, rather than just the path with the lowest number of hops.
-You have heard that routing loops can be a problem and wish to avoid them. However, you are concerned that if a link goes down, there should be redundancy so that traffic will go through.

How can you accomplish your objectives? What routing protocols and protocol features will you use to do so? Provide detailed examples.

Solution Preview

Static routing requires network administrators to constantly check and update each router's individual routing tables. As an example, if the network today has 10 routers (and their respective subnets) and a new 11th router (with its new subnet) is added, all 10 existing routers' routing tables will need to be modified by adding a route to this new router. The new router also needs 10 routes itself to the other existing routers.

As the number of routers and/or subnets continue to grow, the amount of administration overhead increases to the point where static routing cannot scale anymore. In a full-mesh topology--in which each router is connected by a link to every other router--the number of links grows at an exponential rate when the number of routers grows linearly. Mathematically, if n is the number of routers, then the number of links required in a full-mesh topology is n*(n-1)/2, or (n^2 - n)/2. With static routing tables, this calculation is similar as each router has a single route to each of the other routers in the topology, and thus, static routing cannot scale properly in large environments.

Two ways of solving the problems with static routing's inscalability are dynamic routing and default routes. Dynamic routing uses routing protocols to exchange routing information dynamically; in the earlier example of adding a new 11th ...

Solution Summary

About 900 words in total, this solution covers redesigning a company's computer network (LAN) from existing static routes to dynamic routing protocols. RIP, EIGRP, and OSPF are all discussed, as well as the advantages of using them over static routing and their best practices.