[cisco-bba] Does SLB support SIP?

Robert Blayzor rblayzor.bulk at inoc.net
Thu Feb 7 19:48:06 EST 2008

Andy Saykao wrote:
> I'm finding that the SIP headers do not have any of CCM IP's in them 
> ( or 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 so the SIP call hits 
> the SLB and then is load balanced to one of the CCM's???

Your problem is not SLB, it's NAT.  There isn't any mechanism in IOS (at 
least that I"m aware of) or rewrite SIP messages to contain the right 

Perhaps the best option is to ditch SLB + NAT and go to dispatch  mode, 
where the real servers are aware of the virutal addresses via directly 
connected (ie: loopback address).  Of course you'll have a problem with 
UDP based SIP (my guess).

Robert Blayzor
rblayzor at inoc.net

Debugger: A tool that substitutes afterthought for forethought.

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