Sdr Multicast Session Directory
Sdr is a session directory tool designed to allow the advertisement
and joining of multicast conferences on the Mbone. It was originally
modelled on sd written by Van Jacobson at LBNL, but implements a later
version of the session description protocol than sd does.
Sdr binary releases
Binary releases of sdr are available from the MERCI project server at
University College London in the directory ftp://cs.ucl.ac.uk/mice/sdr.
Sdr pre-releases are available from this server. Full releases
of sdr contain encryption code which was written entirely at UCL. Due
to US export restrictions I can not re-release these original versions
of sdr from the US. Thus these pre-releases have been stripped of all
encryption code and the stubs that call it. Anyone wishing to obtain
the original encryption source code can obtain it from UCL's server.
Note: a bug in sdr 2.2 and sdr 2.3 causes these versions to crash
when announcements are received containing no session name field.
This same bug was fixed in Dec 1996 in sdr 2.4. Upgrading to sdr 2.4
will cure this problem but sdr 2.4a6 is still experimental. Feedback
about any problems experienced would be appreciated.
Sdr 2.4a6 contains new session invitation code that is not
compatible with sdr 2.2 or 2.3. This code is still evolving. Future
compatibility is not guaranteed.
Sdr 2.4 uses the administrative scoped range 22.214.171.124 to
126.96.36.199 for local announcements. This improves the
scalability of the address allocation schemes, provides increased
protection against external sessions, and allows pruning back from
your site boundaries. To get these advantages your site's multicast
routing must be configured with a boundary for this scope zone. See
draft-ietf-mboned-admin-ip-space for details. Note: sessions
announced using this local scope are only visible on other sdr clients
that are configured to receive this scope zone. Sdr 2.2 and 2.3 are
not configured this way by default
The following pre-release binaries are available:
Other binaries may be made available as people submit them to me.
The sdr Changes Log is always available, and
reflects the state of the current development version. Sometimes this
is ahead of the released version.
Sdr 2.4a7 source is available as a gzipped
Sdr was written under the MICE and MERCI projects at UCL by Mark
Handley who now works for ISI. Sdr
will continue to be maintained on a limited basis as part of the
infrastructure for conferencing on the CAIRN testbed network. Additional
support will come from the MERCI project. Many many fixes and
improvements to Sdr have been contributed by Bill Fenner and Van
Sdr implements three protocols:
Like all experimental software, Sdr does not implement all the details
found in these specifications. Eventually it may do so....
- The Session Description Protocol for defining the timing and
capabilities of a session. The full specification
- The Session Announcement Protocol for announcing those session
descriptions using IP multicast.
- The Session Initiation Protocol for inviting individual users to
participate in sessions. The full specification is
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