Assistance with Multicast for Paging

mumbles202 · ‎01-10-2024

Trying to work on a configuration that is giving me some issue. Currently have CUCM running at site 1 w/ a local paging server. There are phones on multiple subnets at site 1. Site 1 has a Nexus 7K as the gateway for all devices, w/ sparse-mode configured on all of those interfaces and it's uplink to a WAN router. Site 2 has a similar topology. Paging works as expected at site 1, w/ users on both subnets able to get the pages.

The connection from Site 1 to Site 2 is via IPSEC tunnel that terminates on a router at both sides. The tunnel interface, as well as the serial interfaces the tunnels are sourced from) on both sides has sparse-mode configured, and if I do a "show ip pim neighbor" on either of the WAN routers I'm seeing the other side of the tunnel as a neighbor. Downlinks from both WAN routers have sparse-mode configured, but the phones at site 2 get no audio. They get signaling as the speaker does light up, but that's it.

All of the routers have the rendezvous point, which is at a 3rd site, manually configured.

Wondering what I should be looking at to help to troubleshoot. If I do a "show ip igmp group" on the routers I get they're members of "224.0.1.40"

Georg Pauwen · ‎01-10-2024

Hello,

the problem is usually with the codec, RTP voice ports being blocked, or in some cases NAT can cause this. Can you post the relevant configs ?

Elliot Dierksen · ‎01-10-2024

I haven't had to do this in quite a while, but my recollection is that you should/can only run PIM over the tunnel interface when using IPSEC. I also recall using sparse-dense mode, but I am not a multicast expert.

Edit: @Georg Pauwen makes a good point about codecs. The phone going on speaker indicates that the control portion of paging is working. You'll probably need to IGMP join debugging on the routers on each side of the link.

mumbles202 · ‎01-11-2024

Thanks for the replies. If I do "show ip pim neighbor" from each of the routers w/ the vpn (running ipsec as tunnel tunnel100) I do show the following:

HQ


HQ#sh ip pim neighbor
PIM Neighbor Table
Mode: B - Bidir Capable, DR - Designated Router, N - Default DR Priority,
      P - Proxy Capable, S - State Refresh Capable, G - GenID Capable,
      L - DR Load-balancing Capable
Neighbor          Interface                Uptime/Expires    Ver   DR
Address                                                            Prio/Mode
10.27.99.5        GigabitEthernet0/0/2     3w3d/00:01:21     v2    1 / DR G
10.210.5.12     Serial1/0/0              5d22h/00:01:35    v2    1 / S P G
10.200.21.97      Tunnel230                5d22h/00:01:19    v2    1 / S P G

interface Tunnel230
 description IPSEC P2P to Remote_1
 ip address 10.200.21.98 255.255.255.252

Remote_1#sh ip pim neighbor
PIM Neighbor Table
Mode: B - Bidir Capable, DR - Designated Router, N - Default DR Priority,
      P - Proxy Capable, S - State Refresh Capable, G - GenID Capable,
      L - DR Load-balancing Capable
Neighbor          Interface                Uptime/Expires    Ver   DR
Address                                                            Prio/Mode
10.200.21.98      Tunnel100                5d22h/00:01:39    v2    1 / S P G
10.180.81.1       GigabitEthernet0/0/0     5d22h/00:01:38    v2    1 / G
10.210.5.11     Serial1/0/0              5d22h/00:01:41    v2    1 / S P G


interface Tunnel100
 description IPSEC P2P to HQ
 ip address 10.200.21.97 255.255.255.252

I thought it might be codec issue when going from region to region so I changed 1 of the remote phones to a DP in the same region as a working phone in CUCM but that made no difference. Call control is via jtapi, which the phone is receiving, but the audio stream doesn't appear to be getting there.

I'll try to get the output of the debugs to analyze.