[cisco-voip] Determining if multicast is working properly for CallManager's Music On Hold (MOH)

Voice Noob voicenoob at gmail.com
Fri Nov 23 20:34:27 EST 2007


Well I would check to see if a phone hears music when they are on
hold. Just crazy me.

On Nov 22, 2007 11:47 PM, Andy Saykao <andy.saykao at staff.netspace.net.au> wrote:
>
> Hi There,
>
> We are using CallManager 5.1 and I believe I've set up the network to be
> multicast ready, but I don't know how to confirm that multicast is working
> properly for Music On Hold which is currently being streamed using multicast
> datagrams from our two CallManager servers.
>
> Here's a brief overview of the current set up.
>
> We have all our Cisco IP phones (7961's) set up on vlan 40.
> There's only one core router involved with this set up and various PoE
> switches.
>
> ------------------------------------------------------------------------------------------------------------------
> Core Router (cisco 7206VXR (NPE300))
> ------------------------------------------------------------------------------------------------------------------
> * I've enabled multicast on this router and set up PIM on the respective
> sub-interface.
>
> ip multicast-routing
>
> interface FastEthernet0/0.40
>  description Cisco IP Phone System
>  encapsulation dot1Q 40
>  ip address 172.16.55.1 255.255.255.0
>  ip pim dense-mode
>
> ------------------------------------------------------------------------------------------------------------------switch1-voip
> ------------------------------------------------------------------------------------------------------------------
>
> * The switches all are have igmp snooping enabled as seen below for vlan40.
>
> switch1-voip#sh ip igmp snooping vlan 40
>
> Global IGMP Snooping configuration:
> -------------------------------------------
> IGMP snooping                : Enabled
> IGMPv3 snooping (minimal)    : Enabled
> Report suppression           : Enabled
> TCN solicit query            : Disabled
> TCN flood query count        : 2
> Robustness variable          : 2
> Last member query count      : 2
> Last member query interval   : 1000
>
> Vlan 40:
> --------
> IGMP snooping                       : Enabled
> IGMPv2 immediate leave              : Disabled
> Multicast router learning mode      : pim-dvmrp
> CGMP interoperability mode          : IGMP_ONLY
> Robustness variable                 : 2
> Last member query count             : 2
> Last member query interval          : 1000
> ------------------------------------------------------------------------------------------------------------------
>
> I can see that the multicast group exists on the core router.
> 172.16.55.5 = callmanager1
> 172.16.55.6 = callmanager2
>
> core-routerr#sh ip mroute
> 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
> Outgoing interface flags: H - Hardware switched
> Timers: Uptime/Expires
> Interface state: Interface, Next-Hop or VCD, State/Mode
> (*, 239.1.2.1), 1d03h/00:02:59, RP 0.0.0.0, flags: DP
>   Incoming interface: Null, RPF nbr 0.0.0.0
>   Outgoing interface list: Null
>
> (172.16.55.6, 239.1.2.1), 00:01:10/00:01:49, flags: PT
>   Incoming interface: FastEthernet0/0.40, RPF nbr 0.0.0.0
>   Outgoing interface list: Null
>
> (*, 239.1.1.1), 1d03h/00:02:59, RP 0.0.0.0, flags: DP
>   Incoming interface: Null, RPF nbr 0.0.0.0
>   Outgoing interface list: Null
>
> (172.16.55.5, 239.1.1.1), 00:01:06/00:01:53, flags: PT
>   Incoming interface: FastEthernet0/0.40, RPF nbr 0.0.0.0
>   Outgoing interface list: Null
> But I don't understand why no hosts (ip phones) are joining this multicast
> group (0 joins, 0 leaves)
>
> core-routerr#sh ip igmp interface fa0/0.40
> FastEthernet0/0.40 is up, line protocol is up
>   Internet address is 172.16.55.1/24
>   IGMP is enabled on interface
>   Current IGMP host version is 2
>   Current IGMP router version is 2
>   IGMP query interval is 60 seconds
>   IGMP querier timeout is 120 seconds
>   IGMP max query response time is 10 seconds
>   Last member query count is 2
>   Last member query response interval is 1000 ms
>   Inbound IGMP access group is not set
>   IGMP activity: 0 joins, 0 leaves
>   Multicast routing is enabled on interface
>   Multicast TTL threshold is 0
>   Multicast designated router (DR) is 172.16.55.1 (this system)
>   IGMP querying router is 172.16.9.50
>   No multicast groups joined by this system
> I've followed this troubleshooting article and everything appears correct
> within the switch network:
>
> http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008059a9df.shtml
>
> This CCIE also has a simple set up which I followed but can't confirm if
> multicast is properly working bc I don't see the join counter increasing on
> the sub interface.
>
> http://cciev.wordpress.com/2006/06/17/moh-settings-for-multicast/
>
> Strange enough, MOH is still working eventhough multicast doesn't appear to
> be working. Why would this be the case?
>
> How do I confirm multicast is properly working with CallManager's MOH within
> the network?
>
> Any help or page reference would be greatly appreciated.
>
> --
>
> Regards,
>
> Andy
>
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