Subject: Re: [bmwg] WGLC on IPv6 Benchmarking

From: [email-masked] (Scott O. Bradner)
Date: Sun, 25 Feb 2007 17:20:09 -0500 (EST)

Curtis sed:

> The term "throughput" is commonly referred to as an average rate
> that is acheived given a particular load.  In an operating network,
> the throughput is the number of bits actually flowing, not the maximum
> acheivable rate.  For example, if a 10g interface has 1g of traffic on
> it, the throughput is 1g, not 10g.  The maximum acheivable throughput
> might be 10g (we can pretend it is, though for practical reasons it
> rarely is).  It makes no sense for the benchmarking community to
> redefine a commonly used term that has a somewhat different meaning to
> the rest of the community.  I don't think that was ever the intention
> of RFC1242 but I can't speak for the author.  Scott can clarify.

a lot of thought and discussion went into the definition of throughput
the max zero-loss rate was carefully selected because it turns
out to be quite meaningful

for example, about the same time that RFC 1242 was published a 
particular Wellfleet router was able to forward packets at a rate of
over 85,000 pps (over six 10 Mbps Ethernet paths) but its zero-loss
rate was less than 5,000 (as I recall) because there was a bug which
caused packets to be lost when the real time clock updated the console
screen every second - this was important information - it led to teh bug
being found - in this case fixing that bug increased TCP throughput
for paths going through the router.

bottom line - selecting the max zero-loss value as the "throughput" 
was exactly what the WG wanted to do.

the intention was that people using the RFC 1242 termonology should say
so in their reports to avoid confusion over what they mean with their
test results

Scott

_______________________________________________
bmwg mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/bmwg

---

From: Curtis Villamizar <[email-masked]>
Date: Tue, 27 Feb 2007 15:33:17 -0500

In message <[email-masked]>
> so in their reports to avoid confusion over what they mean with their

Scott,

I think you missed the point of my message by quoting only part of it.
The point was that the benchmarking, operational, and transport people
define "throughput" very slightly differently.  If we define these as
"maximum throughput" (lossless as currently defined), "acheived
throughput" (or utilization), and "end-to-end flow throughput"
respectively and understand that each group shortens their term to
"throughput", we have a set of definitions which are consistent with
current usage.  The slight ambiguity of using the word "throughput"
alone is acknowledged, but within the context of a given discussion
there is rarely any ambiguity.

Make sense?

Curtis

ps - A lot of routers had bugs in those days.  The AGS+ could only
handle four consecutive FDDI packets, consistently dropping the fifth.
This made things entertaining when the EGP packets grew to fill five
fragments (not long before EGP went extinct).  The list is long, and
sometimes amusing to look back on.  btw- I think the clock thing
happened to Cisco and their initial response was "IP is best effort --
so what".  Maybe history repeated itself.

---

From: [email-masked] (Scott O. Bradner)
Date: Tue, 27 Feb 2007 18:29:56 -0500 (EST)

this was taken into account when the BMWG decided to use the term "throughput" 
the WG felt it was teh right term to use

Scott