[cisco-bba] Does SLB support SIP?

[Andy Saykao]

Does anyone know if Cisco SLB can support the SIP protocol? We have a
situation where we need to forward external calls from our SIP gateway
to our Cisco Call Manager 5.1 servers. This is because our SIP gateway
isn't smart enough to distinguish if one of the CCM is down and try the
other one - instead it forwards both calls to the CCM and we get
presented with two calls on our IP phones. We can set the SIP gateway to
forward it to one CCM, but this wouldn't give us any redundancy or fail
over should one CCM fail. 
 
Here's the 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

I'm finding that the SIP headers do not have any of CCM IP's in them
(172.16.55.5 or 172.16.55.6) so obviously the packet gets discarded when
it hits the CCM. Instead the SIP header has the FROM: address as the SIP
gateway IP (203.10.x.x) and the TO: address as the virtual server IP
(210.15.x.x) (which we've set the SIP gateway to forward to) - is there
anyway to have TO address changed to 172.16.55.5/6 so the SIP call hits
the SLB and then is load balanced to one of the CCM's???
 
> INVITE sip:987654321 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:12345678 at 203.10.x.x>;tag=171a2a27c0d677b4b142551fa092f0f0
> To: <sip:987654321 at 210.15.x.x>
> Call-ID: 1C6F6260-D46511DC-84E280E4-D0AAFDDC at 203.10.x.x
<mailto: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
> cisco-GUID: 1494077719-3576435164-2575237145-3119402593
> h323-conf-id: 1494077719-3576435164-2575237145-3119402593
> Content-disposition: session
> Content-Length: 420
> Content-Type: application/sdp 
 
Thanks.
 
Andy

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