Lots of Activity

refram · ‎02-10-2010

I have a new 2821 ISR with IOS 12.4(20)T running CME and loaded with an NM-CUE module. I also have a new 3560G PoE switch running IOS 12.2(35)SE5. When I plug the ISR into the switch, the light above the port starts blinking on and off very rapidly. On the router, the "Activity" light does the same thing. The last time I saw something like that was in broadcast storm situation, but it happens when the router is the only device plugged into the switch. Furthermore, everything seems to be working OK. I've tried a couple of different ports and it's the same. If I do a "show interface" on the router or the switch, I get no errors mentioned. If I plug a couple of phones into the switch they don't have that kind of activity registering and calls can be made just fine. Is that much activity coming from the ISR really normal?

buchholr · ‎02-14-2010

Without having a running configuration to look at, it sounds like you have multicast music on hold configured without having IGMP running. It is harmless in most small networks, but I never like having that much activity showing.

To turn on PIM and, as a result, IGMP and allow the switch and router to "prune" back interfaces that don't need the MoH stream, try the following commands:

ip pim rp-address x.x.x.x (this address is usually preferred to be a loopback on the router)

!

interface TYPE X/X (the interface for the voice vlan, also run this on the interface you used above as your RP)

ip pim sparse-mode

!

This is a very basic config, and I am guessing about the music on hold, as I don't know how you are actually configured. If you want to post a running-config, I can confirm this, and give you a more specific config.

Robert