SIP Record-route problem

Hi Evelin,

If you trying to use SIP profile to insert RR then for sure F5 LTM will add its VS address. To avoid it you can use following I-rule

if { [SIP::to] contains "xyz.com" } {

}

/Regards Amit Grover

Hi Evelin,

  It is little tricky here as F5 has to act as a ALG. F5 has to update/insert the Record-Record header based on where the request/response is coming from.

  If the request/response is coming from Client without Record-Route header then F5 has to insert the header with SNAT IP. But if the header is already present with VIP as value then F5 has to update the value with SNAT IP.

  If the request/response is coming from SIP server without Record-Route header then F5 has to insert the header with VIP. But if the header is already present with value as SNAT IP then F5 has to update the value with VIP.

  To know whether SIP message is coming from Client or SIP server you can use clientside command.

  if { [clientside] } { Message from Client
       SIP::header insert "Record-Route" SNATIP
  } else { Message from Server
       SIP::header insert "Record-Route" VIP
  }

• Syed Nazir

Thanks for the replies, guys. For now I've implemented a simple irule which strips the RR header info for requests being forwarded to SIP server and add RR for any SIP responses being sent from the SIP server to SIP agent. It looks like this:

when SIP_REQUEST_SEND { SIP::header remove "Record-Route" } when SIP_RESPONSE_SEND { SIP::header insert "Record-Route" "" }

It seems to be working fine for now. Our QAs are testing it. If it doesn't work for some reason I'll try with your suggestions.

Thanks again!

You can set the default route on the SIP server (on the private VLAN) to use the Bigip private VLAN Self IP.

Thanks, Godfrey but I cannot change the default GW for the SIP servers to point to the LTM private VLAN Self IP.

The irule I've posted before seems to be working partially...

All the requests coming from SIP clients get translated and forwarded to the SIP server. Replies from SIP servers are going over the LTM Automap NAT IP and then get translated and hit the SIP client.

So far so good.

BUT when SIP server has to terminate the call by sending BYE REQUEST that request is being sent to the SIP phone IP instead of to the Automap Private IP. As we are bloking any traffic coming from Internet on port 5060 on our SIP servers the OK reply message never hit the SIP server.

Do you have any idea how I can make SIP server to send REQUEST messages to F5 Automap private IP instead of to the SIP agent directly?

Thank you!

regards, Evelin

Are you inserting a VIA header on the BIGIP? Having the BIGIP insert a VIA header will ensure the server uses the details in the VIA to send the BYE via the BIGIP instead of the UAC/phone directly.

If you are already inserting a VIA header on the BIGIP then open a ticket with F5 Support and provide a packet and a qkview taken after the packet capture.

Syntax for taking a packet capture will be like below assuming same port is used for vip and pool:

tcpdump -ni 0.0:nnn -s0 "((host( or ) and port )" -w /var/tmp/SIP.cap

Are you inserting a VIA header on the BIGIP? Having the BIGIP insert a VIA header will ensure the server uses the details in the VIA to send the BYE via the BIGIP instead of the UAC/phone directly.

If you are already inserting a VIA header on the BIGIP then open a ticket with F5 Support and provide a packet and a qkview taken after the packet capture.

Syntax for taking a packet capture will be like below assuming same port is used for vip and pool:

tcpdump -ni 0.0:nnn -s0 "((host( or ) and port )" -w /var/tmp/SIP.cap