System information

Troubleshooting TCP/IP 7-131
IP Enhanced IGRP: Router Stuck in Active Mode
Enhanced IGRP and Active/Passive Modes
An Enhanced IGRP router can be in either Passive or Active mode. A router is said to be passive for
a network when it has an established path to that network in its routing table.
If the Enhanced IGRP router loses the connection to a network (for example, Network A), it
becomes active for that network. The router sends out queries to all its neighbors in order to find a
new route to Network A. The router remains in active mode until it has either received replies from
all its neighbors or until the active timer, which determines the maximum period of time a router will
stay active, expires.
If the router receives a reply from each of its neighbors, it computes the new next hop to Network A
and becomes passive for that network. However, if the active timer expires before all its neighbors
reply, the router removes from its neighbor table any neighbors that did not reply, again enters active
mode, and sends a “Stuck-in-Active” message to the console.
Possible Problem Solution
Active timer value
is misconfigured
Step 1 Check the configuration of each Enhanced IGRP router by using the
show running-config privileged exec command.
Step 2 Look for the timers active-time router configuration command entry
associated with the router eigrp global configuration command entry.
The active timer determines the maximum period of time that an
Enhanced IGRP router will wait for replies to its queries. If the active
timer value is set too low, there might not be enough time for all the
neighboring routers to send their replies to the active router.
Step 3 Make sure that the value set by the timers active-time command is
consistent among routers in the same autonomous system.
A value of 3 (three minutes, which is the default value) is recommended
in order to allow all Enhanced IGRP neighbors to reply to queries.
Interface or other
hardware problem
Step 1 Use the show ip eigrp neighbors exec command and examine the
Uptime and Q Cnt (queue count) fields in the output.
If the uptime counter is continually resetting or if the queue count is
consistently high, there might be a hardware problem.
Step 2 Determine where the problem is occurring by looking at the output of the
“Stuck-in-Active” error message, which indicates the direction in which
the problem node is located.
Step 3 Make sure the suspect router still works. Check the interfaces on the
suspect router. Use the show interfaces exec command to display
statistics for all interfaces configured on the router.
For more information, see Chapter 3, “Troubleshooting Hardware and Booting
Problems.”
Flapping route
Step 1 If there is a flapping serial route (caused by heavy traffic load), queries
and replies might not be forwarded reliably. Route flapping caused by
heavy traffic on a serial link can cause queries and replies to be lost,
resulting in the active timer timing out.
Step 2 Increase the bandwidth of the link. For more information, see Chapter 15,
“Troubleshooting Serial Line Problems.”