Information Technology Reference
In-Depth Information
Table9-4
AppleTalk: Zones Missing from Chooser (continued)
Possible Problems
Solution
ZIP storm
A ZIP storm occurs when a router propagates a route for which
it currently has no corresponding zone name; the route is then
propagated by downstream routers.
Note:
Cisco routers provide a firewall against ZIP storms in the
internetwork. If a Cisco router receives a routing update from a
neighbor, it does not propagate that new route until it receives
the accompanying zone name.
1.
Use the
show appletalk traffic
command and check the
field showing the number of ZIP requests.
The following example is output from the
show appletalk
traffic
command:
Router#
sh apple traffic
[...]
ZIP: 44 received, 35 sent, 6 netinfo
[...]
Router#
Compare this output with the output shown by the command
30 seconds later.
2.
If the traffic counters for ZIP requests are incrementing
very rapidly (by more than 10 every 30 seconds), a ZIP
storm is probably occurring.
Use the
debug apple zip privileged exec
command to identify
the network for which the zone is being requested by
neighboring routers. You can also use the
show apple private
exec
command to check the number of pending ZIP requests.
3.
Identify the router that injected the network number into
the internetwork (and that is causing the excessive ZIP
traffic). The
show appletalk traffic
and
show appletalk
route exec
commands provide information that can help
you find the suspect router.
For example, you can use the
show appletalk route exec
command to view the AppleTalk routing table. Check whether
a network shows up in the routing table, even though the display
indicates that no zone is set.
If you find a network for which no zone is set, a node on that
network is probably not responding to ZIP requests, resulting in
the ZIP storm.
Determine why the node is not responding to ZIP requests.
Access lists or other filters might be the cause. ZIP storms
can also result from a defect in the software running on the
node. Contact the vendor to determine whether there is a
known problem.
4.
