Specifications

37
Caveats for Cisco IOS Release 12.0
78-6455-12
Resolved Caveats—Cisco IOS Release 12.0(11)
• CSCdp81134
A Cisco router that is acting as an area border router (ABR) connected to a stub area might place
an Open Shortest Path First (OSPF) external route into its routing table whose outgoing interface
is in the stub area. This situation can cause a routing loop because the stub area routers do not know
about the external route and will forward packets along their default route, which might be the
ABR.
This problem has been found to occur only when there are 2 paths between the stub area ABR and
the autonomous system border router (ASBR) that is originating the external route, where one path
is through the stub area and the second is through a nonstub area(s).
Workaround: Set the link costs within the stub area high enough so that the stub area ABR routers
do not see the path to the ASBR as being as good as the path(s) through the nonstub areas.
• CSCdp95116
In a Protocol Independent Multicast (PIM) Version 2 router configuration, if a hash mask is not
configured on a Cisco bootstrap router (BSR), the router takes the first rendezvous point (RP)
address from the local RP-mapping cache. The RP-mapping cache is not sorted, so when RPs are
added and deleted from the cache, there might be inconsistency through the BSR domain that
causes routers to choose different RPs for the same group.
Workaround: Create a hash mask length of 1 on the BSR router by entering the ip pim
bsr-candidate Ethernet1/2 1 global configuration command.
• CSCdr03120
When you change the Reverse Path Forwarding (RPF) interface for (*,G) and (S,G), the interface
that was in the outgoing interface list (O-list) becomes the new RPF interface. At this point, the
new RPF interface will be deleted from the O-list which becomes NULL. When the router switches
back to the original RPF interface, the O-list remains NULL until the next Internet Group
Management Protocol (IGMP) report. While the O-list is NULL, and the original RPF interface has
directly connected members, the CONNECTED flags are deleted and the router switches back to
the shared tree by sending (S,G,RPT) Join. This situation causes a delay in the convergence time.
There is no workaround.
• CSCdr06681
If there is a link flap somewhere in the network between the area border router (ABR) and an
autonomous system boundary router (ASBR), the ABR might not generate a type 4 summary ASBR
link-state advertisement (LSA) to other areas after the link is restored. The net effect is that routes
being redistributed by the ASBR into Open Shortest Path First (OSPF) will not be installed in the
routing tables in the affected areas.
Workaround: Restart OSPF on the ABR by using the clear ip ospf proc command.
Alternate Workaround: On the ABR, restart OSPF for the affected areas only by removing and
restoring the network statements under the router ospf global configuration command for the
impacted areas.
Alternate Workaround: For this workaround, perform the action only after the subject ASBR LSA
has been removed from the affected areas’ database (no longer seen in show ip ospf database
EXEC command).
On the affected OSPF routers (that are not seeing the routes and the ASBR LSA) adjacent to the
ABR, reestablish adjacencies with the ABR. One way to do this is to temporarily change the
hello-interval to some other value. After the adjacency is taken down, change the hello-interval
back to the original value to reestablish the adjacency. This action causes the ABR to regenerate
and resend the LSAs. On the ABR, create and remove a wrong router ospf global configuration
command (for example, router ospf 1234 and no router ospf 1234).