Looking for ktcpvs but not quite

Erik Versaevel erik at infopact.nl
Thu Jan 13 11:04:25 GMT 2005

No, high persistence won't work because reply packets from another SIP 
source might be balanced to the wrong server, ie packets from might be balanced to real server 1, which sends it's reply 
directly to (the end point for the call) but the replies 
from might end up at another real server.
(be aware i'm using direct routing because of NAT traversal)


Malcolm Turnbull wrote:

> I might be interested in sponsoring someone to develop this, as I've 
> had several customers ask for it (must be a lot of venture capital 
> flooding into VOIP :-).
> Although technicaly I have no idea how it would be done...
> As a work around , wouldn't a high persistence on UDP by source ip 
> work OK ? (allbeit with badly balanced load.)
> Erik Versaevel wrote:
>> Hello,
>> I'm currently trying to create a loadbalacing SIP (voip protocol) 
>> cluster, however for this to work I need SIP messages from the same 
>> call (identifiable by the sip callid field) to get to the same 
>> realserver over and over again. (so, I need persistence based on the 
>> contents of the SIP Call-ID field). This would call for ktcpvs as we 
>> need to process packets at layer 7, however that poses 2 new 
>> problems, the first is that SIP uses clear text  UDP messages, not 
>> tcp and the second is that there are no SIP modules for ktcpvs.
>> Another option would be to mark SIP packets with iptables/netfilter 
>> based on the callid, however i run into the same problem, there are 
>> no modules to accomplish this.
>> I know that there are commercial products available who are able to 
>> do SIP session persistence based on callid, the F5 Big-IP for 
>> example, the downside of that is it costs around $ 10.000 for a 
>> single loadbalancer (which is a SPOF so you need 2) and is a bit 
>> overkill as i don't need multi gigabit loadbalancing.
>> Any thoughts on this?
>> Kind regards,
>> E. Versaevel
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