Route Table Terms

By | July 16, 2013

These are terms commonly used with routing protocols to prevent loops and bad routes from occurring within your network:

  • Hold down Timer – prevents a router from improperly reinstating a route from a regular routing update.  This causes the router to ignore any updates with poorer metrics to a lost network for a given period of time.  
  • Split Horizon – prevents information about a route from being sent in the direction from which the route was learned.
  • Defining a Maximum – prevents invalid updates from looping the network indefinitely by defining a maximum hop value.
  • Route Poisoning – Causes a routing protocol to advertise an infinite metric for a failed route to prevent the route from being used.
  • Triggered Update – decreases convergence time by immediately sending route information in response to a topology change.
  • LSA (Link State Advertisement) – The packets flooded when a topology change occurs, causing network routers to update their topological databases and recalculate routes.
  • Poison Reverse – A router learns from its neighbor that a route is down and the router sends an update back to the neighbor with an infinite metric to that route.