Cisco IOS Cookbook, 2nd Edition

Adjusting Timers

Problem

You wish to tune your EIGRP timers to improve network convergence.

Solution

There are two important EIGRP timers, the hello interval and the hold time. You can adjust both of these timers separately on each interface on a router as follows:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#interface Serial0.1
Router1(config-subif)#ip hello-interval eigrp 55 3
Router1(config-subif)#ip hold-time eigrp 55 9 
Router1(config-subif)#exit
Router1(config)#end
Router1#

Discussion

One of the unique features of EIGRP is that you can adjust its timers separately on each interface. Recall from Chapter 6 that RIP requires you to adjust every router participating in RIP. And in Chapter 8 you will see that while OSPF allows you to adjust the timers separately on each link, you have to make sure that it is the same on all routers on this link. But with EIGRP, you can adjust the timers on one router on a link independently of what you have configured on other interfaces on this router, or on other routers on this link.

EIGRP handles this by simply telling the other routers on the link what its parameters are. Therefore, if one router has a particular hello time of, say, five seconds, then all of the other routers on this link will expect to see a hello packet from this router every five seconds. This is true regardless of what the other routers have for their own parameters. The result is that when you adjust the timers on an ...