Subject: Methodology for IP Multicast Benchmarking

From: "Perser, Jerry" <[email-masked]>
Date: Tue, 28 Nov 2000 18:38:31 -0800

Let me start out with that I agree and support the authors statements on
Appendix A.  "If the distribution is not well defined or understood, the
throughput and forwarding metrics are not meaningful."  Different mixes of
multicast and unicast traffic will produce different results.  This work on
appendix A should be completed.

Here are a few examples of different methods of distributing multicast and
unicast frames.  I do not endorse a particular method.  They are here just
for illustration. A simple test of running 80% multicast; 20% unicast;
Offered Load of 100,000 frames/second; test duration of 10 seconds.

A. Least Common Denominator.  Reduce the ratio of multicast to unicast to
the smallest numbers.  Transmit that number of multicast frames followed by
unicast frames.  This would be 4 multicast to 1 unicast.

B. Percentage.  Convert to whole percent in to frames.  Multicast would be
80 frames and unicast would be 20 frames.  Transmit 100 frames in a cycle of
80,20,80,20...

C. Time Based.  Transmit a class of frames for a period of the test
duration.  For the example, transmit 8 seconds of multicast, then 2 seconds
of unicast.

D. Lottery.  Put all the transmitted frames in a big lottery bucket.  Pull a
frame out randomly from the bucket and transmit him.  In this example, there
needs to be one million balls in the lottery bucket.

Each of these methods transmits EXACTLY the same number of multicast frames
and the same number of unicast frames.  Each method counts the frame loss
the same.  Each method will have the same offered load and forwarding rate
average (over the test duration).  Each of the methods uses a
non-homogeneous environment.  Each just have a different idea what small is.

The DUT results will vary based on how well it handles each method.  The
throughput and latency results will be different.

Can appendix A be finished before releasing another draft?  The mixed class
throughput depends upon how appendix A defines "mixed".

___________________________________________________________ 
Jerry Perser           Phone: 818.676.2320 
SmartLab Manager       Lab:   818.676.2337 
Netcom Systems Inc.    Fax:   818.880.9165 
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Calabasas, CA, 91302   Pager: [email-masked]