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configure or disable ip multicast ttl-threshold on cat4507 12.1(19)

IP multicast documentation suggest the "no ip mutlicast ttl-threshold" command to fix an issue I am experiencing

however my ios  (12.1(19) )does not support that command

could find nothing in command reference

issue is allworx phone system - directly connected to 4507

the paging feature uses mutlicast - it works for 2 minutes across layer 3 vlan interfaces and then fails until voip phones are rebooted

the phone requests to send the page - the allworx controller sends out the muticast advertisments.

sho ip mroute does show T flag - which = SPT bit set

the expirey field decriments  until paging fails see below

I also see incrimenting bad hop count in show ip traffic - a symptom one of the multicast troubleshooting documents described

(,, 00:01:49/00:01:20, flags: T

  Incoming interface: Vlan99, RPF nbr

  Outgoing interface list:

    Vlan6, Forward/Sparse, 00:01:49/00:01:13, H -expirey filed is 00:01:13 - paging still function across layer 3 vlan interfaces ( this has decirmented from a higher value )

(*,, 00:02:34/stopped, RP, flags: DC

  Incoming interface: Null, RPF nbr

  Outgoing interface list:

    Vlan99, Forward/Sparse, 00:02:30/00:00:34, H

(,, 00:02:11/00:02:55, flags: PT - mroute is pruned at this point paging fails across layer 3 vlan interfaces on core

  Incoming interface: Vlan99, RPF nbr

  Outgoing interface list: Null

we tried setting the paging hop count to 5 in allworx ( I asume this reflects TTL)

allworks support wasn't much help.

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Community Member

configure or disable ip multicast ttl-threshold on cat4507 12.1(

Found the issue

we first upgraded the 4507 to 150-2.SG4

but that initself did not change any behavior

after closer inspection of traffic captures between IP phones and Allworx ( the multicast server)

I found that Allworx isn't always using  multicast but sends broadcasts ( the allworx ip is x.x.130.1 so boradcast is x.x.130.255)

the ip multicast-helper on the layer 3 interface did the trick

I had to convert broadcast to multicast on the layer3 interface of the server

first use and acl to define the traffic

access-list 139 permit UDP host x.x.130.1 host x.x.130.255 eq 2088

then convert broadcast to multicast

ip multicast helper-map broadcast 139

and then do the reverse ( multicast to broadcast) at the far end

I used the same acl number but defined it differently

access-list 139 permit udp host x.x.130.1 any eq 2088

ip multicast helper-map x.x.152.255 139

my challenge is now how to handle different multicast groups as the traffic x.x.130.1 UDP 2088 does not change

only the mutlicast group

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