Subject: RE: Duration

From: Jerry Perser <[email-masked]>
Date: Fri, 18 Jun 1999 08:23:34 -0700

The Duration needs to be a MUST.  The DUT/SUT vendor can adjust the duration
to make it look like it does full line rate.  I have seen two switch vendors
run tests in my lab.  The first switch ran full line rate at 60 seconds.
The second switch did 98% at 60 seconds, but full line rate at 30 seconds.
Somewhere around 45 seconds it started to drop frames.  Both vendors claimed
wire speed.  The vendor who failed at 60 seconds saved money by using
smaller buffers.  He claimed he can do wire speed like the other vendor and
was cheaper.  Was this a fair comparison?

The duration MUST be fixed to a standard value to generate consistent
results.

The Duration value needs to be a balance between "buffering effect" and the
"clock tolerance effect".  If the duration is too short or too long, one of
these effects will skew the results.  The Duration of 10 seconds is what has
been published in Data Communications Magazine in the first "Canned Heat"
tests.  The Tolly Group says its standard is 60 second duration (even though
some of the reports are 15 and 30 seconds).

RFC-2285 does not state the duration.  I thought it did.  I will correct the
text not to refer to RFC-2285.  I would recommend a value of 10, 30, or 60
seconds.

David, I have this T1 bridge you might be interested in.  It does 100Mbps
Full Duplex at full line rate for the duration you suggested.

___________________________________________________________ 
Jerry Perser               Phone: 818.676.2320 
SmartLab Manager           Lab:   818.676.2336 
Netcom Systems Inc.        Fax:   818.880.9165     
26750 Agoura Road          Corp:  818.676.2300 
Calabasas, CA, 91302       Pager: [email-masked]