NAT skinny port conflict

Unanswered Question
Jul 28th, 2007

Hi all,

Here my problem I need connect to server on 2000 port its actually manageSIEVE port. Connection setup goes fine SYN->ACK SYN->ACK. When server send me first packet Router thinks its skinny fragmented packet. This packet goes into internal queue and not forwarded of course (wait for other packets I suppose).

In attachment you can find log enabled:

debug ip nat detail

debug ip nat fragments

I don't have command ip nat service skinny - its cisco851 box and yeah I've tried on another box this command doesn't help anyway.

I have this problem too.
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Paolo Bevilacqua Sat, 07/28/2007 - 13:44

Which IOS are you using ? Bug toolkit revela some candidates:


Stack overflow with fragmented skinny packets

Info Information on this bug

Open 2


ISDN T310 timer is not started after recieving Call Proceed.

Info Information on this bug

Fixed 3


nat_portrange_skinny.ccm:Nat translation table fails with SPUD image

Info Information on this bug

Open 3


Enhancement in NAT to have a TCP stack like behavior for skinny

Info Information on this bug

Fixed 3


Inspect skinny blocks EasyVPN skinny client w/NAT, hairpin PBR

nikolay-shopik Sat, 07/28/2007 - 13:50

I'm running latest available 12.4(15)T

ops just notice what 12.4(15)T1 available, going to install it to see if it make any difference

nikolay-shopik Sun, 07/29/2007 - 00:34


Looks like bug I suppose too tried old release c850-advsecurityk9-mz.124-6.T8 with no luck. In mean time I would like to buy support contract from Cisco so I can fill such bugs to cisco tac, can you advice me which one is right for me?


Paolo Bevilacqua Sun, 07/29/2007 - 03:05

Hi Nikilay,

the support contract comes by category depending on the type of equipment, an adsl router is like Cat. 1 or 3, I can check that tomorrow in the office.

nikolay-shopik Sun, 07/29/2007 - 03:48


I'll be really appreciate your help, can you drop me info on my mail shopik at I'm new to support contracts and it's really difficult to choice correct one ;).


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