PIM DR Toggles between two redundant routers

[daleschultz]

We have two 3745 routers configured with 6 FE ports. The routers act as a redundant pair using HSRP for unicast traffic on all 6 fe ports. On each router two ports are used for forwarding MPEG-TS in IP/UDP as multicast traffic (IP:224.20.20.9) from one VLAN (ingress) on fe2/0 out to another VLAN (egress) on port fe2/1. Two things seem to be happening. First, every 3 minutes a duplicate IP packet (as seen by a MPEG-TS analyzer) will be seen on egress VLAN with the source MAC of the non-DR, why?

Second, multiple times a day the DR will switch between the two routers even though the dr-priority has been set higher on the first (lower IP address) router. The network is very static so what might cause this and/or what should we be looking for?

With two FE ports on each router setup for multicast, does the dr-priority have to be setup and the same parmameters used for each interface on a common VLAN?

Thanks for any suggestions.

Dale

[beth-martin]

What version of IOS are you using?

[daleschultz]

Both routers are:

IOS (tm) 3700 Software (C3745-IPBASE-M)

Version 12.3(9b), RELEASE SOFTWARE (fc1)

Copyright (c) 1986-2004 by cisco Systems, Inc.

Compiled Wed 18-Aug-04 17:12 by dchih

[daleschultz]

We have since upgraded the routers to version:

IOS (tm) 3700 Software (C3745-IPBASE-M)

Version 12.3(19), RELEASE SOFTWARE (fc2)

Copyright (c) 1986-2006 by cisco Systems, Inc.

Compiled Fri 12-May-06 0

But there is no change in the symptom. Every 3 minutes a single packet continues to leak through the egress interface of the non-DR on the same LAN as the DR.

[daleschultz]

Following the advise in this bug report (CSCec90275) seems to have resolved our issue with duplicate packets leaking onto the network.