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New Member

Problems with VoIP

Hello,

I have a network with central 3661 and many 2620 connected to it. The scheme is PBX--PRI--3661--PPP--2620--BRI--PBX

I have the following problem. I've configured VoIP over PPP link with cRTP, QoS(LLQ). This configuration worked fine until I restarted the central router. Now when the call goes from central office to remote, the called person hears the call, hears theperson that is calling. But the calling party hears nothing, only silence. What is the possible solution for this ?

Also I receive the following messages after the call from 366101:21:01: %VTSP-3-DSP_TIMEOUT: DSP timeout on event 0x6: DSP ID=0x1: DSP Disc (c

all mode=0)

01:21:03: %VTSP-3-DSP_TIMEOUT: DSP timeout on event 0x6: DSP ID=0x1: DSP error s

tats (call mode=16 )

9 REPLIES
New Member

Re: Problems with VoIP

Did you use the "h323 bind" command to link h323 to an IP address on your routers. You need to do this and then ensure that your dial-peers are configured to point to this address. If a gateway has several IP addresses, the interface that H.323 uses can change depending on how the call is setup if you do not use the "h323-gateway voip bind srcaddr" command. I usually create a loopback address on all of my routers and bind h323 to that address.

There also might be a routing issue. You can do an extended ping and try to ping from each interface on the central router to each interface on one of the remote routers.

The DSP timeout issues might be IOS related. What version of IOS are you running? Check CCO for possible deferral notices or check the bug toolkit for more info.

New Member

Re: Problems with VoIP

I didn't used the "h323 bind" command before, but I did configure it as you suggested. Unfortunately the situation does not change.

As to routing issues, pings are going well to all directions and all interfaces.

I found some bugs on CCO,that give similar error messages, namely with cRTP configured, but after I removed cRTP as was suggested, the problem still remains :(

New Member

Re: Problems with VoIP

I had very similar situation. pbx-3661-2mbps/hdsl-3661-pbx. symptoms the same. router restart fix the problem... ;( regards

New Member

Re: Problems with VoIP

What version of IOS is on your routers? I had a similar problem, except that when I rebooted my gateway, the problem went away. I placed a call with TAC, and they think I've hit a bug (CSCdu53333) in the IOS.

I have 12.2(4)T1, and am trying to upgrade to 12.2(8)T5 or 12.2(11)T.

Steve

New Member

Re: Problems with VoIP

I have 12.2.2T. After restart it begins to work for a while, but after some time, fails again.

New Member

Re: Problems with VoIP

Seen DSP_Timout problem several times with earlier versions of IOS. Upgrade always fixed the problem for me...

New Member

Re: Problems with VoIP

Yestarday I've upgraded 3661 to IOS version 12.2.12a, and after that till now, voice calls flow normally in both directions. Also there are no error messages that I saw on the 12.2.2. But instead the QoS that worked well on 12.2.2 currently doesn't work. The QoS is again bad, although from debug I can see that voice packets are hitting the priority queue. Even more. after a short period of time I've got bigger problems. Applications from remote office do not work at all, and as I see, big packets do not pass through the routers. Ping with small packets goes without problem, but ping with 500 bytes doesn't go at all. After I removed the service-policy, fragmentation, interleaving and rtp compression from interface it begins to work normally. Certainly with bad QoS for voice.

New Member

Re: Problems with VoIP

We may be experiencing the same issues. 12.2.7(4)T on 3620,3640,3660s

Voice call starts up ok (two way) but then, after a short period of time, drops one direction. VoIP over PPP w/ LLQ, LFI, cRTP & cTCP Headers. Problem not consistant but appears related to current code and LLQ.

Note: Working code that covers our requirements difficult to obtain. Most upgrades are missing one or more features (broken code). Any upgrades require extensive regression testing.

Appreciate any heads up the forum may have.

New Member

Re: Problems with VoIP

On 12.2.12 I currently I do not have one-way voice problems. Insted there are other issues. When I configure fragmentation on 3661,voice quality is good, but applications in the remote office do not work at all I have one online application for which I also reserve some bandwidth in the channel, and other best effort traffic like mail etc. When I remove fragmentation, data goes normally, voice quality is bad :((

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