Deprecation of the replace-session-connection flag

[Gianluca Merlo]

Hi,

while testing a recent version of rtpengine (Debian package 12.5.1.2-1~bpo12+1) with a working Kamailio configuration I happened upon the warning

> [core] replace-session-connection flag encountered, but not supported anymore.

I see that in a trivial scenario removing the flag from the rtpproxy_manage call in Kamailio makes the warning go away, while still performing the relevant replacement in the SDP c= line.

I tried to get a better understanding but stopped a little short of digging the exact code (saw a couple of commits on the topic). May I ask, just to be safe, if I am understanding correctly that since 12.5 the replacement in the SDP c= line is always automatically performed, and the only change users are required to implement is to drop replace-session-connection from used flags, without any significant catches?

Thanks in an advance

[Richard Fuchs]

This flag actually used to address just one particular corner case,
where a c= line is present both at the session level and in the media
(m=) section. Without the flag, the only the media-level c= line would
be replaced, and the session-level one would be left alone (a quirky
legacy inherited from the rtpproxy foundation). We're moving towards
more streamlined output SDP formatting and in the future will have only
media-level c= lines and no session-level c= lines, obsoleting this
flag, while hoping that there aren't any silly user agents out there
that insist on having the c= line in a particular place. This conversion
isn't complete yet, but the flag has already been deprecated in
preparation, which in practice (finger crossed) shouldn't have any impact.

Cheers

[Gianluca Merlo]

Thank you, all clear! I guess the bad habit of always including the flag from old code, and never having read with the due attention into it, made me completely miss the relevance of "session-level" in the documentation. I greatly appreciate the effort in explaining it for dummies like myself!

Best regards

[Christian Pauli]

Hi,

We updated our RTPEngine servers to version 12.5.1.5.
We use the flag from the kamailio:  replace-session-connection
Now we have an issue that could from to this feature.
In the SDP, we have at the session level the "c=" that seems not replaced by the RTPEngine IP address.
The media level is ok.
If I read the RFC 8866, it is written that we can have both c= in the Session Level and in the media level.
Is it a bug or a change in this version? 

The "c=" line (connection-field) contains information necessary to establish a network connection.¶

A session description MUST contain either at least one "c=" line in each media description or a single "c=" line at the session level. It MAY contain a single session-level "c=" line and additional media-level "c=" line(s) per-media-description, in which case the media-level values override the session-level settings for the respective media.¶

Thanks in advance for your help.

[Pete Kelly]

Hi all

Hope you don't mind me resurrecting this thread. Did the work to add an alternative to replace-session-connection get completed? 

I have trawled through the latest NG documentation and can't see anything that jumps out that would allow me to manipulate (or remove) the c= line that is present at session level.

Pete