[cisco-voip] Is there a way to rewrite SIP headers?

[Jason Aarons (US)]

Do you have a 'fixup protocol sip' option in the SLB (where you are
Nating)?

 

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Andy Saykao
Sent: Friday, February 08, 2008 1:49 AM
To: cisco-voip at puck.nether.net
Subject: [cisco-voip] Is there a way to rewrite SIP headers?

 

Traffic Flow:

 

External Calls -> PortaBilling / SIP Gateway (203.10.x.x) -> Cisco SLB
Load Balancer (210.15.x.x) -> Either CCM1 (172.16.55.5) OR CCM2
(172.16.55.6) -> User Agent

 

What we are finding is that the Cisco SLB (load balancing) is working ok
and the packet reaches one of the CCM's - but the CCM's are discarding
the packet because inside the SIP header, the TO: address does not
contain the IP address of the CCM (see packet capture below taken from
the CCM end). 

 

> INVITE sip:613xxxxxxxx at 210.15.x.x:5060 SIP/2.0
> Via: SIP/2.0/UDP
> 203.10.x.x
> :5061;branch=z9hG4bK4a2139daf022d80af26275540f1b5722;rport
> Max-Forwards: 70
> From:
> <sip:0404xxxxxx at 203.10.x.x>;tag=171a2a27c0d677b4b142551fa092f0f0
> To: <sip:613xxxxxxxx at 210.15.x.x>
> Call-ID: 1C6F6260-D46511DC-84E280E4-D0AAFDDC at 203.10.x.x
> CSeq: 200 INVITE
> Contact: Anonymous <sip:203.10.x.x:5061>
> Expires: 300
> User-Agent: Sippy

 

You can see that once the packet reaches the CCM, it STILL contains the
address of the SLB virtual IP (210.15.x.x) in the SIP header. Is there a
way to change the sip header information in the To: field. We need
210.15.x.x. rewritten to point to our Cisco Call Manager (172.16.55.5 or
172.16.55.6) so that the packet won't be discarded and call setup can
continue.

 

This is our SLB config:

 

ip slb serverfarm CCM-REAL
 nat server
 predictor leastconns
 real 172.16.55.5
  inservice
 real 172.16.55.6
  inservice
!
ip slb vserver CCM-VIRT-TCP
 virtual 210.15.x.x tcp 0
 serverfarm CCM-REAL
 inservice
!
ip slb vserver CCM-VIRT-UDP
 virtual 210.15.x.x udp 0
 serverfarm CCM-REAL
 inservice

 


Thanks.

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