[ns] Announcement - PGM for ns v2.1b8 (and above)

[Ryan Barnett <rbarnett@usc.edu>]

For those interested in PGM (Pragmatic General Multicast), I have
completed a new implementation of PGM for ns v2.1b8 (and above) that
follows the IETF draft v6 standard as closely as possible.

You can find the tar archive at the following URL:
http://www.isi.edu/nsnam/dist/pgm-070101-2.1b8.tar.gz

You will need to extract it into a vanilla distribution of ns 2.1b8 and it
will override any modified files (but still leave .orig originals).  You
will need to re-run configure and recompile with make.  The PGM code has
currently only been tested on the unix platform.

This version will also be incorporated into the ns distribution in future
releases (it may be in the current snapshot).

Please read the documentation, ~ns/pgm/pgm-howto.txt, located in the tar
archive that gives a detailed description of how to use the package.  Also
see the numerous examples in sim1.tcl, sim2.tcl, sim3.tcl, and sim4.tcl.

1. What is supported?

All general PGM procedures are supported, including at least the
following:

Senders:
   a. Multiple PGM senders on a single network,
   b. RDATA generation,
   c. NAK reliability,
   d. Source Path State generation.

Network Elements:
   a. Source Path State processing,
   b. NAK reliability,
   c. Constrained NAK forwarding,
   d. NAK elimination,
   e. Constrained RDATA forwarding,
   f. NAK Anticipation.

Receivers:
   a. NAK suppression (with a random back-off interval, following the
      state machine described in the specification),
   b. NAK reliability.

2. What is NOT supported?

This implementation of PGM does not support the following features
described in the PGM specification.  These are left for future
enhancements:

   a. PGM Options: These include fragmentation, late joining, redirection,
      Forward Error Correction, reachability, and session control.

   b. Designated Local Repairer (DLR) support.

   c. Congestion control techniques.

   d. Transmit Windows and Receive Windows. The sender is assumed to have
      an infinitely large buffer to provide a repair retransmission for
      any sequence number.

All of the tunable parameters can be found in the 'pgm-howto.txt'
document.

Ryan S. Barnett

rbarnett@usc.edu
Masters of Science in Computer Science
University of Southern California