Hi Gang

I'm having another go with a dedicated kamailio running topos to replace a B2BUA SBC.

I came across this situation:

Server Topology:

Kamaiolio SBC (topos) <=> Kamailio Registrar <=> Kamailio Router (DLG + CDRS)

Core IP Address 10.0.0.1 Registrar IP 10.0.0.2

Two different CPE are registered on Registrar via SBC

One CPE is calling the other CPE

So the path the call is taking is:

CPE A => SBC => Registrar => Core => Registrar => SBC => CPE B

Invite A => B goes through, no issue.

180 Ringing, required 100rel B => A requires the route to be recorded therefore contains 3 record route statements:

Record Route: sip:10.0.0.2;lr Record Route: sip:10.0.0.1;lr Record Route: sip:10.0.0.2;lr

To ensure answer will get route back to the registrar => core => registrar and then the contact pointing to the SBC with topos to restore the last hop.

Ringing B => A works as expected and is answered by A with PRACK.

topos would now need set Route: in this PRACK message, according to the received Record Route Header.

Unfortunately I fear Topos 'removes' the routes with duplicate host ip.

I only get:

Route: sip:10.0.0.2 Route: sip:10.0.0.1

Causing the Core not to be able to route the PRACK back to the registrar.

To test, which line is being dropped, I added an mark to each one and determined the 3rd Record Router is being dropped by topos, probably considered a duplicate.

I found no setting of the 'do not perform record route header dupe detection'.

Interestingly, when I look at the database field topos_d.b_rr all three entries are present in the correct order.

Has anyone come over the same issue and found a solution?

Maybe related to: https://github.com/kamailio/kamailio/issues/3778 ?

Mit freundlichen Grüssen

-Benoît Panizzon-