Problems with 12.3(11)T IOS train w/ MGCP. Recommended alternatives?

Unanswered Question
Apr 5th, 2007

It seems like there's been several posting regarding bugs observed in the latest IOS version on MGCP gateways. Symptoms are channels not registering, one-way audio, or inbound calls immediately dropping. Today, I was hit by all three of these running 12.3(11)T11 on a 2821 w/ VWIC-2MFT-T1s. Resetting, re-configuring MGCP from scratch, and even rebooting failed to resolve it. Downgrading to 12.3(11)T10 magically fixed everything.

At this point I thinking of switching over to 12.3(14)T7 based on the top post, but before doing that does anybody have a bug-free version that they've been using and would recommend? I've used 12.4(8) on a 2811 with no troubles, but that was H.323.

This seems fairly widespread, happening on the 2600XM, 2800, and 3800 platforms, both 12.3T, 12.4, and 12.4T. However, I've yet to see a specific bug on this issue.

I have this problem too.
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thisisshanky Thu, 04/05/2007 - 21:02

Johnny, Why dont you try mainline 12.4 ? Its definitely a lot better than buggy versions of 12.3.

johnnylingo Fri, 04/06/2007 - 06:16

That's what logic would dictate, and like I said I've run 12.4(8) on an H.323 gateway with no trouble at all.

However, if you scan the postings I've linked to, you'll see mention of undocumented bugs in both 12.4T and 12.4 Mainline. I've been watching this since January and still don't see a firm resolution, which is why I stuck with 12.3(11)T rather than move to 12.4. I had upgraded to 12.3(11)T11 to address bug CSCse15025.

thisisshanky Fri, 04/06/2007 - 07:05

A few tips i can give about these mgcp issues. I have noticed these in 12.4 IOS a lot.

a. Configure ccm-manager config and ccm-manager config-server so that mgcp process on the router will download the right packages. Once you have configured this the following commands will show up on the configs. A lot of people dont like having the ccm-manager config command in there as it takes the ds0s down when a config change happens. So you may remove these commands after the commands mentioned below are downloaded to the router.


mgcp call-agent 2427 service-type mgcp version 0.1

mgcp dtmf-relay voip codec all mode out-of-band

mgcp rtp unreachable timeout 1000 action notify

mgcp modem passthrough voip mode nse

mgcp ip qos dscp cs3 signaling

mgcp package-capability rtp-package

no mgcp package-capability res-package

mgcp package-capability sst-package

no mgcp package-capability fxr-package

no mgcp timer receive-rtcp

mgcp sdp simple

no mgcp fax t38 ecm

mgcp rtp payload-type g726r16 static

mgcp bind control source-interface FastEthernet0/0

mgcp bind media source-interface FastEthernet0/0


mgcp profile default

b. Bind media and control source addresses to a interface whose ip address is reachable from callmanager, unity, phones etc. There is a bug related to this, where mgcp process resets and the binding is some how lost even though the commands to bind the address are still there in the config.

c. Configure no mgcp timer receive-rtcp. Without this command if a phone puts the call on mute, after a few minutes the call gets disconnected. Again step a should automatically add this command to the config.

d. I have found this bug in 12.4 without any fixes yet. If using SRST on the router and when MGCP fallsback to H323, you can place calls just fine. But if you reboot the router in srst mode, the pris doesnt come back up when the router has booted back up completely.



johnnylingo Fri, 04/06/2007 - 07:45

Very helpful, thanks. Honestly though, I'd be more inclined to stay on 12.3T or just convert to H.323 rather than deal with these issues on several gateways deployed in multiple locations. I have a go-live for a Hospital next month, so everything needs to be as solid as possible by then. Will be interested to hear what TAC has to say on this.

thisisshanky Fri, 04/06/2007 - 09:09

Also try pushing the TAC engineer to check if there are any dspware issues that may be causing this. H323 is so solid, i have never had any problems with it, except for the amount of configs you got to put in place.

johnnylingo Mon, 04/09/2007 - 16:39

Interestingly enough, even after downgrading to 12.3(11)T10, I was hit with another outage the next morning, although this was different in that after rebooting, no PRIs would even register. Moved to 12.4(7e) and that fixed one of the gateways, but the other still would not register any PRIs.

On the gateway that was having problems, we'd actually had a bad T1 off it for the last few days. The telco had done tested and said it was our equipment. I did a "shutdown" on the T1 controller, and everything immediately registered and worked fine. After finally convincing them to send a technician out, they found a loose wire at the demarc point.

So the root cause was actually a bad wire on the T1, however the fact that it hosed the MGCP backhaul on multiple gateways is pretty scary. I'm thinking until this risk can be elimated, I'll just use H.323


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