[cisco-voip] R: TCP ZeroWindow

[Ryan Ratliff]

Does the packet capture at the CUCM server show the same zero-window packet that you see at the phone?

-Ryan

On May 21, 2010, at 6:19 PM, Mauro Celli wrote:

> I have analyzed the problem better.
> his is my situation:
> One remote cucm 6.1 (3Gb memory,2gb free/cached) connected with cisco 2811 10Mbit mcr xds, and five sites connected with cisco 877 dsl (300k mcr) . 
> All work over mpls.
> Four of the sites work correctly.
> In fifth site,if the phone is in iddle, it send and receive keepalaive correctly.
> If i press on phone down button (to show latest calls) and exit and i repeat for some times,
> it send some skinny message (why??? is the exit button???) and after some packets,it receive an ack with 0 window (ttl ok).
> No syslog lines on cucm.
> Now it continue to  exchanges skinny keepalive.
> Now if i press line button,the phone exchanges skinny packet and keepalive with cucm but it hung.
> During the hung,it continue to  exchanges skinny packet and keepalive.
> In the phone log,i see nothing until it auto-reboot with a tcp timeout.
> In cucm syslog,i see the phone unregistered and re-registered.
> If i check “remote device” in phone configuration, i continue to see 0-window and same packets in the same situation
> but the phone not hung and work correctly.
> In this situation the problem is introduced very very very less frequently.
> The line seem to work correctly,same situation with and without qos.
> Switch are all catalyst and the lan work correctly.
>> From cisco site i see that  “remote device” is for slow skinny response,not for hunging phone...
> And why in other four sites same phone with same firmware works correctly?
> Thanks
> ________________________________________
> Da: Wes Sisk [wsisk at cisco.com]
> Inviato: venerdì 21 maggio 2010 20.12
> A: Mauro Celli
> Cc: cisco-voip at puck.nether.net
> Oggetto: Re: [cisco-voip] TCP ZeroWindow
> 
> If you see 0 window you must be looking at packet capture.
> 
> In the IP TTL for the 0 window packets, are the TTL consistent with other frames in the stream?  This would confirm the 0 window is coming from CM and not some interim device such as a firewall or inspection device.
> 
> Beyond that the only reason I have seen 0 window from CM is byproduct of a memory leak on the CM server.  Do you see indication of increased VMRss or file descriptors on CM when this happens?
> 
> /Wes
> 
> On Friday, May 21, 2010 11:19:45 AM, Mauro Celli <mauro.celli at 2000net.it><mailto:mauro.celli at 2000net.it> wrote:
> Hi,
> my remote cucm 6.1 ,sometimes send a TCP ZeroWindow packet and my phone stop responding for some times (30sec or 30mins) reboot and reconnect.
> If i check “remote device” in phone configuration no TCP ZeroWindow appear and phone work well.
>> From another site all is ok.
> I have checked my line with download,flood etc.. and it’s ok, no lost packet…
> Why?
> Thans
> 
> Cordiali saluti
> Mauro Celli (work in progress...)
> Site: www.2000net.it<http://www.2000net.it/>
> 13011 Borgosesia (VC) Italy
> Via XXV Aprile,41
> Tel.   0163.209111
> Fax.  0163 .209301
> Supporto tecnico: 0163 .209561
> Email: mauro.celli at 2000net.it<mailto:mauro.celli at 2000net.it>
> 
> [cid:part1.03020000.09040707 at cisco.com]
> 
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