EIGRP timers (hello, hold and active)

Today at work I have run into troubleshooting an EIGRP problem with one of our customers; while troubleshooting this problem I started making every optimization I know about EIGRP. In this post I am sharing with you EIGRP timers I adjusted in order to clear up the problem.

Hello interval timer:

Hello interval is the rate at which EIGRP sends hello packets. The command ip hello-interval eigrp can be used to set the hello interval time manually.

Hello interval defaults to 60 seconds for low-speed, NBMA networks and 5 seconds for other types of networks.

Hold timer:

This is the amount of time that a router will consider a neighbor alive without receiving  hello packets. The hold time is typically three times the hello interval. You can adjust the hold time with the ip hold-time eigrp command.

Unlike OSPF changing the hello timer does not automatically adjust the hold timer.

Sometimes hello packets are lost in congested networks and neighbor relationships start to flap; in such cases you may want to increase the hold time.

Increasing the hold timer delays convergence, this is  an undesirable effect. If the default hello/hold time value is not suitable for your network try to find the value that best suits your network.

Active timer:

This timer controls the time the router waits after sending a query before declaring the route stuck in active (SIA) and resetting the neighbor relationship. To avoid this neighbor resetting you can temporary increase the active timer until you solve the problem by eliminating the cause.

The timers active-time command can be used to adjust the active timer.