[cisco-voip] MGCP Odd issue

[Barry Howser]

Hi Wes. The "mandatory missing IE" message was at the end of a q931 debug
right before the call goes busy. I may have over simplified my original
explanation. I have several gateways that this exact same scenario happened
to. All experienced the same condition, with the same configurations.

On Tue, May 26, 2015 at 3:33 PM, Wes Sisk (wsisk) <wsisk at cisco.com> wrote:

> a couple things here -
>
> you say MGCP.. if using MGCP and d-channel bachaul then it is CCM’s ISDN
> stack in use. Where did you see the error “mandatory IE missing?” if it was
> with debugs on the gateway then it may have been generated by the gateway’s
> ISDN stack.
>
> each isdn ‘switch type’ has subtle nuances in implementation. the right
> answer really depends on what physical equipment the telco is using as well
> as how they have the d-ch provisioned on their end.
>
> it could be the telco changed config. or they might have upgraded the
> switch. or you may have started using a different call flow that
> added/removed IE’s.
>
> also possible that a lingering reset/restart was not applied on the UCM
> side (CSCtw80866    Reset Required flag in CCMAdmin for any device/trunk
> that has been )
>
> -w
>
> On May 26, 2015, at 2:44 PM, Barry Howser <bhowser5050 at gmail.com> wrote:
>
> So I've had an MGCP/T1 gateway up and running with CCM, happy as a clam
> for several weeks.
>
> Then all of the sudden today it stopped passing inbound communication.
> Egress works just fine, but ingress rings once then a fast busy.
>
> In the ISDN logs I get "mandatory information element missing".
>
> I am using; EF, BZ8S, Primary-ni (which is telco settings). Again
> everything WAS fine. After some research I found that error to mean that
> the CCM side kicked the call back to the gateway because it didn't get
> everything it needed in the header.
>
> A proposed suggestion was to use a different switch-type. So in the
> CCM/Gateway/PRI config page, I changed the switch type to PRI-4ESS ->
> Saved/Applied/Reset (then restarted mgcp on the gateway) and presto,
> ingress is now working.
>
> If I reverse the process and go back to the Primary-ni in the
> CCM/Gateway/PRI config, I get the same problem with ingress again.
>
> Can anyone explain this to me? Does it sound like my telco changed
> something? Seems like something with MGCP is goofed right? Is this
> something that a telco would just arbitrarily change?
>
> Thanks
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