Multicast issue post upgrade to 16.0.619

[Nick Wright]

It seems that updating to 16.0.619 has introduced a bug where the default TTL for multicast packets used by the multicast paging feature is set to 1. This means that the packets will not leave their original subnet as the TTL value means any router will drop them. We have separate server and voice vlans in our organisation which effectively means that our multicast paging is now broken. has anyone else experienced this issue?

Does anyone have a solution.

 

[NickD_3CX]

Hi Nick,

I double-checked against an older version (v15.5 SP6 specifically) and the "Time to live" value is also set to 1, so this does not seem to be the source of the issue.

Which version were you running before were you had this working?

 

[Nick Wright]

We went from 16.0.4.504 to 16.0.5.619 and multicast ceased to work. A TTL of 1 will cause any router to confine the multicast to the originating subnet.

 

[NickD_3CX]

I checked the build you mentioned and from the testing, on Windows only, it was indeed sending a different value.
I just want to say that this was never intended to be like this. The design thought behind multicast paging was to be confined to the same subnet only.

What you can do however is add a second network adapter to your 3CX Server on the other subnet and then Multicast RTP Packets should be sent out on that one as well

 

[Nick Wright]

That's really odd, multicasting to different subnets has always worked for us, for at least 18 months anyway. I'll try the additional adapter, Thanks

 

[Nick Wright]

Tried the additional adapter, failed miserably, all our outbound calling ceased to work. We really need to be able to either set the TTL as a parameter or the default be set to 32 instead of one.

 

[JohnS_3CX]

Hi Nick,

Did the 2nd adapter have a gateway set? Disable the gateway if that was the case.

 

[Nick Wright]

It did, I'll try without, thanks