What is Link State Routing

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Optimized compared to distance vector routing Link state routing Routing structures by making calculations on the best routes. instead of just passing the routing table information between the routers. Link state routing only sends interface information about the various interfaces that exist on a router and the networks to which the router is connected. Instead of sending a routing table with 20 to 50 entries, link status updates only send information about the four to six interfaces on the router.

Understand the connection status log

Each router stores all of the link status information it receives in a topological database , what a table is that contains connection information. via all known routers. It does not define routes; Instead, it records all the information necessary to get to each network segment connected to each router after the routing information has been calculated.

There will likely be more than one route to each network. Therefore, it is important to evaluate every possible route to find the best route to each network segment. You can do this with the Shortest Path First (SPF) algorithm, , which then creates the SFP tree.

Since the router knows all connections in the network, it can evaluate all connections on its own in order to find the most efficient way to reach every other network segment in the network. This is known as the shortest path to each of these network segments. All shortest paths are stored in one place called the SFP tree.

After the SFP tree has been created, the router checks it to find the best possible route to each network. After the best routes are found, the router adds them to its own routing table. This routing table is created on each router, but it should be the same for all routers receiving the same updates because they all use the same process to create the routing table.

When a router starts up and sends its initial link status information to its neighbors, it reduces network overhead by only sending updates to its link information. These Connection status s (LSA) are flooded to all routers in their area or zone. LSAs are just updates to their connection status, so a connection is sent whenever a link is connected or disconnected.

Working with your strengths

This update handling system appears to be key to the strength of link-state protocols. Although there are some differences between the two protocols, link state protocols generally differ from distance vector protocols in the following ways: You can decide whether these differences are advantages or disadvantages:

  • Cost metrics are the primary determinant of route selection; these cost metrics are the point of evaluation to determine the best links, which may include the speed and capacity of the links.

  • Less frequent routing updates.

  • High degree of scalability to support much larger networks.

  • Division of the entire network into smaller segments in order to limit the scope of the routing changes.

  • Only updates on link status and topology changes are sent.

  • Triggered updates can notify systems immediately of changes and reduce convergence times.

  • Network design can reduce the size of the link state database. When the network ID is designed to support route aggregation, the reduced number of routes reduces the size of the link state database.

  • Limited age of the data, as the aging of the LSA always keeps the information up to date.

  • Routing loops are almost eliminated because routers know what the overall network topology looks like.

  • Large amounts of memory are required to support not only the routing table but also the link state database and the adjacency database (the table listing neighboring devices).

  • Running the Dijkstra algorithm (the math formula used to do the shortest path calculation) requires the use of CPU cycles on the router, and for larger networks this requirement means more CPU time for calculations.

  • In large network implementations, link state protocols can require a lot of tuning to function properly. This need can be a significant challenge for a network administrator.

If you have enough CPU and memory resources on your network routers, and your network layout is not overly complicated, you shouldn't be suffering from the problems associated with link state logs - just take advantage of the benefits. There is no reason that link state protocols should not be used as the primary routing protocol on your network.