Subject: RE: Latency and load

From: Jim McQuaid <[email-masked]>
Date: Mon, 23 Aug 1999 14:36:06 -0400

I think the current discussion is about what might be the ingredients of
"correct way" since there is no specific definition in 1944/2544 about
multiport devices.  Multiport devices probably have different latency
characteristics for different paths but that is a real rathole!!

Jim McQuaid
Ganymede Software

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]
Sent: Monday, August 23, 1999 1:31 PM
To: [email-masked]
Subject: Latency and load

I have another question regarding the Latency and Load issue. 

How many port pairs are you utilizing when running the latency test  ?? If
you
were testing a 12 port switch ,for example, are you running the test on all
6
port-pairs simultaneously or are you only utilizing a single port-pair. I
have
seen it done both ways by different test labs and I was wondering which is
the
correct way.

Randy Forsland
Allied Telesyn Int'l

---

From: Jeffrey Dunn <[email-masked]>
Date: Mon, 23 Aug 1999 21:59:21 -0400

Jim,

This problem has been addressed in the ATM world by running what is
called a trombone test. In the trombone test, an ingress port is chosen
and connected to the method of test (MOT). The MOT sends traffic to the
input of the ingress port which, in turn, has its output connected to
another port.  This port, in turn, has its output connected to the input
of the next port.  In this fashion, all ports are saturated at the
selected bandwidth.  The last port is the egress port.  The output of
this port is connected to the input of the MOT and the frames or cells
are counted and their intergrity is monitored.  This may not be
applicable to all network equipment; however, ATM switches and routers
can be configured to execute this sort of test.

Jeff Dunn
Advanced Network Consultants

>Jim McQuaid wrote: