[cisco-voip] Call drop issue

[Michele Russo (AM)]

All,

I am working with a customer who is seeing sporadic call drops on their systems.  They following is the setup:

CME - H323 Trunk to Avaya - call routed out a LD PRI registered to the Avaya system.

The CME has 12 7937's and 4 biamp devices registered to it, the Biamps are SIP based phones.  The off-net calls drop sporadically and the seemingly relevant messages we see in the Wire Shark and Syslog  traces show:


10.146.128.50 (Avaya)    10.146.149.65     TCP        [TCP ACKed lost segment] h323hostcall > hfcs-manager [ACK] Seq=1 Ack=2 Win=8736 Len=0
TCP0: bad seg from 10.146.128.50 -- bad sequence number: port 35839 seq 2919846836 ack 1534185920 rcvnxt 2919846837 rcvwnd 3146 len 0
TCP0: ACK timeout timer expired

With a disconnect Cause Value=38 (meaning network out of order).

I am attaching the router config, the syslog file and the Wireshark capture.

Note:  the CME and the Avaya re on the same 4507E switch and a review of both interfaces show literally zero CRC, Frame, Overrun or other L2 issues.  So it seems unlikely that there are any cabling issues, and the switch itself seems quite healthy.

Any thoughts/suggestions would be very helpful!  So far TAC has suggested we add the 'no vad' statement to the dial-peer 11 and allow-connections h323 to h323.  I am not sure either one of those configuration changes will fix this issue.

Thanks!

Michele Russo
Consultant
Dimension Data NA
202-460-3965 (cell)
571-203-4007 (desk)
michele.russo at dimensiondata.com
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