Subject: RE: RE: [bmwg] BMWG Last Call: draft-ietf-bmwg-igp-dataplane-conv -*** -10

From: [email-masked]
Date: Mon, 10 Apr 2006 17:41:08 -0400

Thanks David.  I will be sure to use "Throughput" and not any other
derivation.  

I find your second comment to be quite interesting.  Does this mean that use
of Throughput only (and not Forwarding Rate) as exists in the -10 versions
of the Terminology and Methodology is correct?  I believe so.

Scott

-----Original Message-----
From: David Newman [mailto:[email-masked]]
Sent: Monday, April 10, 2006 5:34 PM
To: [email-masked]
Subject: RE: RE: [bmwg] BMWG Last Call:
draft-ietf-bmwg-igp-dataplane-conv -*** -10

On Mon, 10 Apr 2006, [email-masked] wrote:

> Yes Al.  You bring up an important distinction that
> 1. the Offered Load to the ingress interface of the DUT should equal the
> maximum Throughput as defined in RFCs 1242 and 2544

A couple of nits:

1. This is no such thing as maximum throughput. As defined in 1242, 
throughput is a single rate.

Marketdroids have thoroughly abused the term for years with monstrosities 
such as "maximum throughput," "zero-loss throughput" (in which "zero" 
sometimes contains a one), and so on.

For implementers actually following the RFC, there's only one throughput 
level and it refers to only one rate.

2. The 1242 definition of throughput requires observations at both the 
ingress and egress sides of the DUT/SUT.

Two concepts in the definition are observed on the ingress side -- the 
rate and the number of offered frames. One concept is observed on the 
egress side -- the notion of no drops, which is verified by comparing 
egress-side receive counts with ingress-side transmit counts.

dn

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---

From: David Newman <[email-masked]>
Date: Mon, 10 Apr 2006 14:49:47 -0700 (PDT)

> of the Terminology and Methodology is correct?  I believe so.

Sorry, I haven't read the current IDs.

Throughput is the appropriate metric if the goal is to measure the maximum 
rate at which the DUT/SUT forwards with zero loss. For any other 
forwarding-type measurement, I believe forwarding rate (or one of its 
variations, as defined in 2285) would be more appropriate.

dn

---

From: Al Morton <[email-masked]>
Date: Mon, 10 Apr 2006 23:30:39 -0400

At 05:49 PM 4/10/2006, David Newman wrote:
>Scott wrote:

Rate-Derived Convergence Time requires
a measurement of rate at the DUT egress,
taken over very short time intervals,
to characterize the effect of re-convergence time
on forwarding.

As David nicely summarized, Throughput offers no rate measurement
>egress-side receive counts with ingress-side transmit counts.

So, Forwarding rate seems to provide the needed info,
Throughput alone is not enough.

Al