SCN Calls often unobtainable 3

[tipu2010]

Hi, am setting up a SCN between main office IP500 (v5.0.22) and branch office IP500 (v5.0.22) over a VPN with CISCO ASA5510 firewalls at each site.

1608 phone screen often shows "CALL:UNOBTAINABLE" when SCN extension is dialed.

10% of calls go through on first dial
40% of calls go through on second dial
30% of calls go through on third dial
20% of calls will require more 4 or more redial attempts before getting connected to the remote extension.

This happens when calling both ways round.

During the cause of the call the voice may go silent/missing for two-three seconds but line does not drop and then conversation continues.

 

[mattKnight]

>the IPO is rather particular about its h323 packets being messed about with. You might need to consider whats more important right now and maybe consider if the ASA is the right product.

Why is that? Does anyone know - My suspicion (and it is just that) is that the Avaya (IPO) implementation of H323 is subtly different from the standard.

Discuss!

Take Care

Matt
I have always wished that my computer would be as easy to use as my telephone.
My wish has come true. I no longer know how to use my telephone.

 

[hairlessupportmonkey]

im really only talking from experience TBH.

Cisco, Sonicwall, watchguard all mess around with H323 and break it, until you tell the firewall to stop it!

I really think its down to what the IPO is expecting vs what it gets after the firewall inspects / filters it.

I wonder what sort of dodgy payloads you can insert into an RTP stream anyway? I want to know why firewalls even need to filter it?

ACSS - SME

 

[mattKnight]

>I really think its down to what the IPO is expecting vs what it gets after the firewall inspects / filters it.

Thats the point of my question...

One(or possibly both) devices seem to use a slightly different "flavour" of H323. Which one is truely standard compliant?

Firewall people want *everything* filtered and inspected *always* RTP is no different...

Take Care

Matt
I have always wished that my computer would be as easy to use as my telephone.
My wish has come true. I no longer know how to use my telephone.

 

[latitude12]

AFAIK the Cisco and Juniper 'inspection' engines are geared around getting H323 to work through NAT, rather than any security issues.

I can't comment on standards compliance, but I know that Avaya do things differently to Cisco, who are certainly going to be the benchmark for Cisco data products (and probably other networking vendors as well).