Subject: Re: Naming those hunks of data

From: Harald Tveit Alvestrand <[email-masked]>
Date: Thu, 01 Oct 1998 10:43:35 +0200

At 05:42 01.10.98 +0200, Bob Mandeville wrote:
>I'd like to suggest 'session time' which avoids twisting  layer 2 lingo like
>forwarding rate and offered load to have a meaning in the context of layer
>3/4/5 measurements. Session time must be explicitly related to the content
>of the session.

Several different opinions on what we want to define here, I think.
"PDU" is usually one data item moving in a single direction.
"Transaction" is usually a sequence of several data items moving in
multiple directions. For database people, it also says "commit/rollback",
and "slow".
"Flow" is usually several data items moving in the same direction.

If we want a generic term that can be twisted to cover all of these
areas of meaning, I'd suggest "unit of work", or "UOW".
Then we can say things like

"when measuring HTTP/1.1 operation throughput, the time spent on the UOW is
measured from the first byte of the HTTP command arriving to the last byte of
the HTTP response; time spent in TCP setup is not included"

or

"when measuring RTP throughput, the UOW is a single packet"

                     Harald A

-- 
Harald Tveit Alvestrand, Maxware, Norway
[email-masked]

---

From: [email-masked]
Date: Thu, 1 Oct 1998 22:55:16 -0400

Harald:
     
     True enough; however, within the unit of work, you are masking a 
     multitude of sins (or virtues, depending on your view point  ;->), in 
     that different authentication mechanisms and/or encryption algorithms 
     will add varying amounts of overhead to the transfer of "the first 
     byte of the HTTP command arriving to the last byte of the HTTP 
     response."  Because of this "apples to oranges" problem, I suggest 
     that the elementary unit of data transfer be measured only after:
     
     1. All security associations have been checked and verified
     2. All connection oriented hands have been shaken
     
     Again, this is not to say that the time required to complete the above 
     two operations should not be part of the benchmarking terminology and 
     methodology.   Rather, I suggest that these measurements be separate 
     from the actual data transfer, which allows a more unbiased assessment 
     of a particular firewall's capability.
     
     Regards,
     
     Jeff

______________________________ Reply Separator _________________________________
Subject: Re: Naming those hunks of data
Author:  Non-HP-Harald.Alvestrand ([email-masked]) at 
HP-USA,mimegw2
Date:    10/1/98 4:43 AM

     

or

                     Harald A

---

From: Harald Tveit Alvestrand <[email-masked]>
Date: Fri, 02 Oct 1998 08:37:42 +0200

>     of a particular firewall's capability.

Maybe.....I think this is a case-by-case thing; the ways in which setup
cost is associated with units of work can be many and confusing
(in HTTP/1.0 "traditional" it would make much more sense to measure from the
SYN bit to the FIN bit, since every page lookup required a separate TCP
connection).
(OTOH, in HTTP, authentication typically requires two transactions; one
to know that it's needed, and one to attempt to authenticate. A third
lookup in the same auth-domain would not require a third round)

                Harald A