Information Technology Reference
In-Depth Information
Table9-4
AppleTalk Enhanced IGRP: Router Stuck in Active Mode (continued)
Possible Problems
Solution
Flapping route
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.
Take steps to reduce traffic on the link, or increase the
bandwidth of the link.
Older version of
the Cisco IOS
software
If problems persist, upgrade to the latest release of the
Cisco IOS software.
Enhanced IGRP 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. The route is in Active state
when a router is undergoing a route recomputation. If there are always feasible successors, a route never
has to go into Active state and avoids a route recomputation.
If the Enhanced IGRP router loses the connection to a network, it becomes active for that network. The
router sends out queries to all its neighbors in order to find a new route to the network. 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, has expired.
If the router receives a reply from each of its neighbors, it computes the new next hop to the network and
becomes passive for that network. However, if the active timer expires, the router removes from its
neighbor table any neighbors that did not reply, again enters Active mode, and issues a “Stuck-in-Active”
message to the console.
AURP: Routes Not Propagated Through AURP Tunnel
Symptom:
AppleTalk routes are not propagated through an AURP tunnel. Routes that are known to exist
on one side of the tunnel do not appear in the routing tables of the exterior router on the other side of the
tunnel. Changes on the remote network (such as a route going down) are not learned by the exterior
router on the other side of the tunnel.
