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TC6.2.1 issues after losing network connectivity

We've had a bit of a reccuring issue recently where, intermittently, if an endpoint running TC6.2.1 loses then restores network connectivity, it can't be called.  It re-registers to VCS and can dial out OK, but incoming calls fail.  In all cases, a reboot fixes the issue.

We've observed this on multiple EX90s, C-series and MX300s.  It doesn't seem to be a timeout issue - in many cases, the endpoint has been back on the network for an hour or more but still won't accept incoming calls until it's had a reboot, but in all cases can dial out fine.  We've also never seen this issue in TC5.X.

VCS search history shows "No route to destination" for the calls that don't work.

Endpoints are running TC6.2.1, registered with H323 to VCS-C 7.2 cluster.

22 REPLIES

Re: TC6.2.1 issues after losing network connectivity

I should also add, that when I check the registration on VCS after restoring network connectivity, it still shows the old registration rather than a new registration.

Diagnostics show no errors (other than "auto negotiation" as we need to have duplex hard set).  TMS Systems > Navigator shows the endpoint as registered also.

TC6.2.1 issues after losing network connectivity

Hi Nick.

I think I red about this behavior here before.

I did not find anything in the cisco bug tool. If you really can rule out

some firewall or router timeout and you have a service contract why dont

you escalate this to TAC and let us know what the result was!

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TC6.2.1 issues after losing network connectivity

Hi Martin,

Yes I can definitely rule firewall etc out - in the testing I've been conducting, the endpoints and VCS are just one router hop away with nothing of note in the network configuration that might be interfering.

I guess it's TAC time.

Re: TC6.2.1 issues after losing network connectivity

So I've logged this with the TAC, the issue is still not solved but we've done quite alot of testing. Here's what we've found:

I've tested every version between TC6.1.1 and TC6.3.0 - it seems the issue affects TC6.2.0 and above. TC6.1.2 and below are unaffected - I couldn't find anything in the TC6.2.0 release notes that would indicate what might be causing the issue between the versions?

  • The issue only occurs while using H323 - if I register as SIP, it's not a problem.
  • I tried registering to different VCS which was running X7.2.2 but the problem still occured.
  • It doesn't matter what the "calling" endpoint is - SIP phones, H323 video endpoints or TP server, whether from the local VCS or a neighbouring VCS/CUCM, all fail to call the affected endpoint.
  • I tried manually clearing the registration on VCS after replacing the network cable and waiting for the endpoint to re-register. It re-registers OK but still can't recieve a call.
  • Tried factory resseting one of the affected EX90s and using minimal configuration for H323 calls (gatekeeper, E164 and H323 ID). The problem still occured when these were the only non-default settings configured.
  • Lastly, I was incorrect when I said the issue was intermittent - it's 100% reproducable and is fixed 100% of the time by a reboot, at least in my environment. The TAC has thus far been unable to reproduce it.

TC6.2.1 issues after losing network connectivity

Hi Nick,

thx for the feedback (+5)

Did you do some trace? I still can picture that there is some timer in your network / router which might

be the reason, ...

Do you have any chance to put a system on the same logical network as your vcs? Just to see if it would

happen there as well?

I recall that some behavoir on h323 regards timeouts had changed, there was a forum post regards this

but I neither recall the tc version when it changed nor did I find the posting when I was just trying to find it.

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TC6.2.1 issues after losing network connectivity

Hi Martin,

I've had both endpoints and the VCS all in the same subnet, literally nothing but a switch in between, issue still occurs.  No port security, 8021.x or anything else strange.

Remembering that while the endpoint can't recieve incoming calls, it re-registers to VCS, can make outgoing calls and I can ping/browse to the GUI once the network connection is plugged back in, which indicates to me that the network is working fine.  Given that I manually cleared the old registration on VCS and allowed the endpoint to re-register and it's still occuring, I don't think it's a registration timeout issue (unless the issue is localized to the endpoint).

VIP Green

TC6.2.1 issues after losing network connectivity

Hi Nick,

I had a similar issue with one of my C60s earlier this week.  The C60 could call out to anywhere (SIP and H.323 registered), but no H.323 calls inbound would connect (I didn't try a SIP call to it).

As per your troubleshooting, a reboot of the codec fixed it and I haven't see it re-occur.

Have you had a chance to try TC6.3 to see if there's a fix in there somewhere?

Wayne

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Wayne
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TC6.2.1 issues after losing network connectivity

Wayne: Nick posted that he tried TC6.3 (at least I assume in between also includes TC6.3  :-)

Still, doing a network trace could be interesting as well as to enable h323 debug logging.

Besides that I guess the best is to wait what TAC has to say.

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Re: TC6.2.1 issues after losing network connectivity

Just to clarify, yes I've tried TC6.3.

You're probably right that I will need to do a trace...

Wayne: I wonder if you pull the network cable of the C60 for a minute (until it says "No Lan") then replace it and see if the issue re-occurs.

      

What version are you running on the C60s? As per my previous post, it seems TC6.2.0 and above are affected.

VIP Green

TC6.2.1 issues after losing network connectivity

Sorry, missed that post about you trying TC6.3.  Will be interesting to see what you can find with your traces and if you can see something missing.  I'll try to have a better look at this end if I see it occur on the C60 that did it before again.

Wayne

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Wayne
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Cisco Employee

TC6.2.1 issues after losing network connectivity

Is it possible you do this and run a packet capture AFTER you reconnect the network back in? In the trace, do you see 1720 being RST when VCS tries to open? Just curious. 

VR

Patrick

TC6.2.1 issues after losing network connectivity

Hi Patrick,

To update, I've logged this with the TAC (SR 627952653).  I ran a packet capture on both endpoints and the VCS.  The packed capture for the affected endpoint contained data from both before and after the network was plugged back in.


It's also probably worth mentioning that I've upgraded to TC7.0.1 but no change - it still seems all versions after 6.1.1 are affected.

Re: TC6.2.1 issues after losing network connectivity

Further update:

The TAC said I am probably hitting this bug:

CSCum04312:  C40 cant receive H323 call.Port 1720 doesnt open after upgrade to TC 6.2

I don't have permissions to view the bug so I'm not sure if/when the target fix version is.  It may be worth changing to include other TC endpoints (we are seeing it on C60, C20, EX90 and MX300 G1.  Haven't tried SX20 or EX60).

Cisco Employee

Re: TC6.2.1 issues after losing network connectivity

Looking at you EX90 pcap file that you've uploaded, frames 30 and 31.  Seem to fit the bill. 

The bug listed seems to fit, but will have to confirm.  Will look a bit more later tomorrow.  I think its easily reproducible by doing what your describing, so will take that and see where it goes. 

VR

Patrick

Re: TC6.2.1 issues after losing network connectivity

Thanks Patrick

Cisco Employee

Re: TC6.2.1 issues after losing network connectivity

Hi Nick.  Do me a quick fave if you can.  Looking at the EX90 config in your case, seems you have:

xConfiguration Network 1 IPStack: "Dual"

and..

xConfiguration Conference 1 CallProtocolIPStack: IPv4

Can you change both to IPv4?

Curious to the outcome. 

VR

P2

Re: TC6.2.1 issues after losing network connectivity

Hi Patrick,

That was actually something I've tried before with no luck (I just tried it again under TC7 just in case, still no good).

I played with those settings quite a bit in my initial troubleshooting - I found that occasionally, it would work after a change (either to dual stack from IP4, or to IP4 from dual stack) but then if I unplugged/replugged the network it would stop working again.

I assumed this was because I was giving the network and/or H323 stack a "kick in the guts" rather than due to any particular setting, as it would exhibit the same problems regardless of what the setting actually was.

Re: TC6.2.1 issues after losing network connectivity

Update on this after another email from the TAC:

Logged in as root under TC7.0.1, entering the command:

netstat -anp --tcp | grep 1720

gives me the following output (where 10.0.0.1 is the codec IP):

tcp          0              0 10.0.0.1:1720                  0.0.0.0:*              LISTEN                  2548/main

After I pull and replace the network cable, the same command doesn't give me any output at all, indicationg that it's not listening on port 1720.

According to the TAC, that bug was supposed to be fixed in TC7.0.1.  Not sure if this is a different bug, but it certainly seems to be exhibiting the same issues.

Cisco Employee

Re: TC6.2.1 issues after losing network connectivity

HI Nick.  Would you be willing to try TC7.0.2 RC1 to test in your environment?

Let me know.

VR

Patrick

Re: TC6.2.1 issues after losing network connectivity

Sure

      

Update:

TC7.0.2 fixed the issue!

New Member

TC6.2.1 issues after losing network connectivity

Thanks for the good news. I am getting slowly angry here with 6.3.0 systems getting unresponsive after a weekend or a while. Interestingly, 6.3.0 is not mentioned in the Bug description.

Danny

VIP Green

TC6.2.1 issues after losing network connectivity

Thanks for the update Nick.  I've seen it happen on a couple of my devices again recently.

Glad to hear that it's fixed in the new release!


Wayne
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Wayne
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