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Routing - Distance Vector vs Link State

There are 2 types of routing protocols. Distance Vector vs Link State.

Distance Vector

Distance vector protocols use a vector of distance and direction to find the best path, where distance is defined in terms of a metric and direction is defined as the next-hop router. Distance vector protocols broadcast the entire routing table at periodic intervals and are slow to converge because of hold-down timers. Examples include RIP and IGRP. Distance Vector routing protocols advertise all the known routes out off each interface.

  • Route Poisoning – Gives a “down” route a infinite metric “16” to show it is down.
  • Split Horizon – Updates cannot be sent out the same interface that they came in on.
  • Split Horizon with Poison Reverse – Failed Routes are given a infinite metric but failed routes are advertised out the interface which the update came from.
  • Hold-Down timer – When the router learns that a route has failed ignore any other update for that route for the certain period.
  • Triggered Updates – When a route fails it sends a flash update regarding the routes status.

Link State

Link-state protocols use a topological database that is created on each router. This database keeps track of directly attached neighbors, the entire network, and the routing table. Link-state updates are typically multicast to all neighbors. (OSPF is a link-state protocol.)

About the Author

RDonato

R Donato

Rick Donato is the Founder and Chief Editor of Fir3net.com. He currently works as a Principal Network Security Engineer and has a keen interest in automation and the cloud.

You can find Rick on Twitter @f3lix001