Archive for the EIGRP Category

EIGRP Basics…

Posted in EIGRP on February 22, 2009 by itdaddy

EIGRP uses Dual algorithm to build its routing t ables. The following are terms that deal with the core of EIGRP:

  • FD  – feasible distance
  • AD – advertised distance
  • Successor – Primary route
  • Feasible Successor – Secondary or backup route
  • Active – dual is using the route in its calculations
  • Passive – dual is not using the route in its calculations

How Feasible successor candidate becomes feasible successor:

To be considered a feasible successor, the AD of the feasible successor candidate must be less than the FD of the successor.

Once the feasible successor is picked, it makes it to the Topology Table. There are three tables in EIGRP we are concerned about:

  • Routing Table – Successor
  • Topology Table -shows feasible succesor
  • Neighbor Table – neigbors