Enabling Multicast on mixed Layer 3 / Layer 2 switches

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May 2nd, 2007
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I'm trying to switch my Music on Hold streams from Unicast to Multicast, and am hitting some snag when enabling multicast on the network. The core of the network consists of 4 6500 switches, 2 as core, 2 for servers. All are Native mode with SUP720s. The 2 core switches are then connected to 3560 closet switches, which just run at Layer 2.


On the 6500s, I've set "ip multicast-routing", and also "ip pim sparse-dense-mode" on all Layer 3 interfaces. I've also done all the required steps in CallManager, and can see the CallManager join the group:



Server-6500-1>sh ip igmp group 239.1.1.1

IGMP Connected Group Membership

Group Address Interface Uptime Expires Last Reporter

239.1.1.1 Vlan2 12:52:51 00:02:15 10.1.2.170


Also, when I put a phone on hold, I see it join the group as well:


Core-6500-1>sh ip igmp group 239.1.1.1

IGMP Connected Group Membership

Group Address Interface Uptime Expires Last Reporter

239.1.1.1 Vlan20 00:05:02 00:02:34 10.1.20.11


And the outgoing interface gets updated both on the server and core switch:


Server-6500-1>sh ip mroute 239.1.1.1

IP Multicast Routing Table

Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,

L - Local, P - Pruned, R - RP-bit set, F - Register flag,

T - SPT-bit set, J - Join SPT, M - MSDP created entry,

X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,

U - URD, I - Received Source Specific Host Report, Z - Multicast Tunnel

Y - Joined MDT-data group, y - Sending to MDT-data group

Outgoing interface flags: H - Hardware switched, A - Assert winner

Timers: Uptime/Expires

Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.1.1.1), 14:00:02/00:03:28, RP 10.1.3.12, flags: SJCF

Incoming interface: Vlan3, RPF nbr 10.1.3.12, Partial-SC

Outgoing interface list:

Vlan255, Forward/Sparse-Dense, 00:00:01/00:03:28, H

Vlan251, Forward/Sparse-Dense, 13:11:57/00:02:45, H

(10.1.2.170, 239.1.1.1), 13:11:57/00:02:52, flags: FT

Incoming interface: Vlan251, RPF nbr 0.0.0.0, RPF-MFD

Outgoing interface list:

Vlan2, Forward/Sparse-Dense, 00:00:01/00:03:28, H



Core-6500-1>sh ip mroute 239.1.1.1


IP Multicast Routing Table

Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,

L - Local, P - Pruned, R - RP-bit set, F - Register flag,

T - SPT-bit set, J - Join SPT, M - MSDP created entry,

X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,

U - URD, I - Received Source Specific Host Report, Z - Multicast Tunnel

Y - Joined MDT-data group, y - Sending to MDT-data group

Outgoing interface flags: H - Hardware switched, A - Assert winner

Timers: Uptime/Expires

Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.1.1.1), 00:36:18/00:02:47, RP 10.1.3.12, flags: SJC

Incoming interface: Vlan255, RPF nbr 10.1.4.13, Partial-SC

Outgoing interface list:

Vlan20, Forward/Sparse-Dense, 00:00:12/00:02:47, H


However, I get silence on the phone (not even the 3 quick beeps), and the layer 2 switch shows no multicast packets received:


3560-20>sh int fa0/22

FastEthernet0/22 is up, line protocol is up (connected)

5 minute input rate 2000 bits/sec, 3 packets/sec

5 minute output rate 65000 bits/sec, 80 packets/sec

451542 packets input, 116439487 bytes, 0 no buffer

Received 5185 broadcasts (0 multicast)


Could there be a step I missed, or is it a problem with the CallManager MoH stream?

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