CMS - encrypted call to H.323 system with high packet loss

[UweSchaefer]

Hi,

we are currently facing the problem that calls from our Meeting Server to some H.323 endpoints in the Internet have a high percentage of lost packets for the incoming streams when the call is encrypted (the call and call legs etc. are established without any errors/warnings/...). If we make the call to the same destination unencrypted, everything works without any problems and any packet loss.

Some other H.323 endpoints work fine with encryption. The parameters (encryption cipher, codecs for audio and video) are the same according to the details seen under /api/v1/callLegs/.

The Meeting Server is within our network. Outgoing connections are routed via the Expressway C and then out to the Internet via the Expressway E. Only the Expressway E is "speaking" H.323, within our network everything is signalled with SIP.

We have updated the CMS last week from version 3.3 to 3.5 but we are not sure whether this is actually the reason for this behavior or whether there were some changes on the other side that cause these problems.

Any ideas to why we see such a high packet loss on the CMS for encrypted connections?

Thanks in advance for any ideas, help, ...!

Regards,

Uwe

[UweSchaefer]

In the meantime we found the solution for our problem. Since encrypted H.323-Calls from other clients (Jabber, Roomkit) were also not working, we searched elsewhere and together with logs from the remote system, we found that the Expressway E offers both 1024-bit and 2048-bit Diffie-Hellman keys for the encryption to the remote system and that caused the problems.

After we disabled the 2048-bit keys on the Expressway E with "xConfiguration Interworking Encryption KeySize2048: Off" the calls are working (again).