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New Member

1 way audio....sometimes

Getting one-way audio sporadically where a caller from remote site will call in and at some point the audio to the remote side dies. The audio to the local listener can still hear the remote side. Gets better. If the remote side puts the call on hold then resumes the call the audio stream is re-connected. I did a packet capture and I see an ICMP port unreachable answer for the RTCP packet the remote side sent right before it loses the audio. Any ideas?


Re: 1 way audio....sometimes

Any firewalls involved in this setup? Could be a global timer disconnecting your H.232/245 sessions (if you're using H.323 that is).

One-way audio is often caused by routing issues. Have you checked connectivity between all devices i.e. Pinging from your Voice VLAN's in both directions etc?


New Member

Re: 1 way audio....sometimes

There is a PIX but all the fixup statements for Voip are on it. The routing issue was what I suspected first but there is nothing I could find along the path. What global timer are you refering to?

fixup protocol dns maximum-length 512

fixup protocol ftp 21

fixup protocol h323 h225 1720

fixup protocol h323 ras 1718-1719

fixup protocol http 80

fixup protocol ils 389

fixup protocol rsh 514

fixup protocol rtsp 554

fixup protocol sip 5060

fixup protocol sip udp 5060

fixup protocol skinny 2000

no fixup protocol smtp 25

fixup protocol sqlnet 1521

fixup protocol tftp 69

Re: 1 way audio....sometimes

Maybe you can find something useful on this link:




Re: 1 way audio....sometimes

Good link Farrukh (3 points for you).

I was referring to the H323 h225 1720 timer. On our FWSM we were seeing these sessions time out.

New Member

Re: 1 way audio....sometimes

I thought about a timer but the times I lose the audio are all over the place. Sometimes its 1 minute into a call and the maximum so far has been 13 minutes. I will see if I can find what the timeout value is.

New Member

Re: 1 way audio....sometimes

Turned out to be a IOS issue on the 1rts router the audio traveled through.

New Member

Re: 1 way audio....sometimes

What version of IOS was this a problem with?