Multicast Configuration For PA

[Guy Greenshtein]

Hi,

I'm using the PA (Public Announcment/Paging) capabilities of my VoIP system but I've encountered some issues regarding it's functionality.

Here is my topology:

Both IP phones, speakers and PA server reside in the same VLAN and network scope.

The issue is that when I try to page from one phone to the rest I don't always here myself on all devices. Sometimes It work and sometimes it work partially but all very random and no certain combination.

I suspect that maybe some multicast configuration is missing along the way. I would appreciate your help.

It's impossible for me to post any configuration or troubleshooting output because of confidential reasons.

Thanks in advance!

[Dennis Mink]

is the PA server in a different subnet from the speakers and phones? so you would need to configure igmp.

without you sharing the configuration it will be near impossible to solve this issue.

[Dennis Mink]

is the PA server in a different subnet from the speakers and phones? so you would need to configure igmp.

without you sharing the configuration it will be near impossible to solve this issue.

[Guy Greenshtein]

No, the server, speakers and phones are all on the same subnet.

[gmgarrian]

What VoIP system are you using?  CUCM, CUCME?  What phones?  What is the PA system?

How is the paging setup?  If all devices are on the same vlan then layer three routing should not be an issue and you would need to make sure each device is getting the message to join the multicast stream.  You would need to get captures and traces to see how the RTP is flowing and how the signaling is working.

Also, rule out any other network issue like duplicate IP addresses.

[Guy Greenshtein]

I want to add an important note.

When I page from one phone I do hear the 'paging beep' on the phones, but sometimes it's just silent and I hear no voice but it seems like the phone does sense that someone is paging.

Another thing we've noticed while testing is that if one of the building switches is connected directly to the core switch then there's no issue at all.