Looking for ktcpvs but not quite

[Wensong Zhang]

Hello,

On Thu, 13 Jan 2005, Erik Versaevel wrote:

>
> 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.
>

We cannot use ktcpvs, because ktcpvs supports TCP only, and there is no
SIP modules for TCP transport.

> 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.
>

The firewall marking doesn't solve the problem. However, we can write a 
special SIP UDP scheduling module for IPVS. It can detect the Call-Id from 
UDP packet and send it to the SIP server according to the recorded Call-Id 
table. We assume that there is no UDP fragments. Some NAT boxes (such as 
early IOS version of Cisco router) may drop UDP fragements except the 
first one.

Regards,

Wensong