Controlling EIGRP behavior by configuring Hello and Hold Timer for faster convergence

When we talk about route convergence, EIGRP converges very fast even with the default settings. One of the slower components of the EIGRP convergence process relates to the timers the EIGRP neighbors use to recognize that the neighbor ship has failed. If the interface over which the neighbor is reachable fails, IOS changes the interface state to anything other than “up/up”, then the router immediately knows that the neighbor ship should fail.

However, in some cases, the interface state may stay “up/up” during times when the link may not be operational. In such scenario EIGRP convergence relies on the Hold Timers to expire, which by default on LAN means a 15 sec wait and on T1 and slower with encapsulation of Frame Relay is 60 sec. Therefore, to optimize the convergence time, engineer can simply reduce the Hello and Hold Timers to 2 and 6 respectively.

Example:

 interface fastethernet 0/1

Ip hello-interval eigrp 100 2

Ip hold-time eigrp 100 6

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