Subject: xconf und SDP

From: Wieland Holfelder <[email-masked]>
Date: Tue, 20 May 1997 13:59:32 +0200 (MET DST)

we receive lots of sdp announcements over sap that do not conform 
to the 03.2 draft by Mark and Van. The draft says, each session
description *must* have a connection information field (c=) but 
like in the following (randomly choosen) example of one of those 
sessions mentioned above, the "c=" field is missing in the session
description part:

v=0
o=mni 3072544278 3072544513 IN IP4 171.68.109.99
s=RTP-RP
i=RP team....
e=Monica Ni <[email-masked]>
p=Monica Ni 919-472-2261
t=3072513600 3074961600
r=86400 28800 0
a=tool:sdr v2.2a23
a=type:meeting
a=xconf.cache:RVS SdpCache v0.1 ts=3073106427
a=xconf.proxy:RVS SdpProxy v0.1 ts=3073107836
a=xconf.email:[email-masked]
m=audio 28578 RTP/AVP 0
c=IN IP4 224.2.129.25/127
a=ptime:40
m=whiteboard 40984 udp wb
c=IN IP4 224.2.236.62/127
m=text 51072 udp nt
c=IN IP4 224.2.206.177/127

We have a parser that is a little more picky than sdr (which does not
complain) and therefore rejects the announcements as soon as it sees 
the "t=" field because it expects a "c=" field there. Sometimes also
the following "t=" field is set to "t=0 0" which doesn't make that 
much sense?

Looking at the attribute fields this only happens when xconf is 
involved. Lutz, is this something you could fix?

Thanks,
-- Wieland
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Wieland Holfelder                              University of Mannheim
Praktische Informatik IV                      Phone: +49-621-292-5679
L 15,16                                       Fax  : +49-621-292-5745
68131 Mannheim                     [email-masked]
Germany                    http://www.informatik.uni-mannheim.de/~whd
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From: "Lutz Grueneberg, RVS" <[email-masked]>
Date: Tue, 20 May 1997 15:37:24 +0200 (MET DST)

Hi Wieland,

> sessions mentioned above, the "c=" field is missing in the session

In fact this is an error in our sdp composer module. The announcements
came from our proxy announcer. The accident is that the proxy announced
with a wrong TTL. I just killed the announcer so no further announcements
should leave the campus any more.

Sorry,
 Lutz
--
// Lutz Grüneberg                Lehrgebiet Rechnernetze und Verteilte Systeme
//                               Universität Hannover
//                               Schloßwender Str. 5
// [email-masked]     D-30159 Hannover, Germany
// Public PGP-Key available: http://www.rvs.uni-hannover.de/people/gruen.html
//                           http://bs.mit.edu:8001/pks-toplev.html

---

From: Peter Parnes <[email-masked]>
Date: Fri, 23 May 1997 11:14:28 +0200

[email-masked] said:
> Sometimes also the following "t=" field is set to "t=0 0" which
> doesn't make that  much sense?

I'm guilty (my mAnnouncer daemon) for the t=0 0 fields and I just checked the 
SDP draft and found the following specifying it to be a permanent session 
which I think makes very much sense. The session in question here is the 
'Places around the world' session.

> If the stop-time is set to zero, then the session is  not  bounded,
>    though it will not become active until after the start-time.  If the
>    start-time is also zero, the session is regarded as permanent.

/P