Subject: [Diffserv] DiffServ MIB

From: "Joel M. Halpern" <[email-masked]>
Date: Mon, 31 Jul 2000 19:55:30 -0400

[Rephrasing what I suggested in the room to get wider review.]

Looking at the MIB I have some concern about the current usage of 
IfDirection scattered through many MIB objects.  It is used (together with 
TCB) to decide where packets start there travels through the processing in 
each direction.

I would like to suggest that IfDirection be removed from all of the tables 
where it now appears.
Instead, have a single table indexed by IfDirection.  The only attribute in 
this table would be a RowPointer to the row describing the first thing to 
do to packets traveling in that direction.  In the case where the 
RowPointer points to the classifier table, it implicitly points to all 
classifier entries in the same TCB as the Row that is pointed to.

This effectively factors out the IfDirection from all the tables to allow 
it to be used effectively for its intended purpose.
I believe that a side effect of this would be to remove any concern in the 
processing path about the falues used to identify different TCBs.

Yours,
Joel M. Halpern

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From: Geoff Huston <[email-masked]>
Date: Tue, 01 Aug 2000 10:18:00 +1000

At 07:55 PM 7/31/00 -0400, Joel M. Halpern wrote:
>Instead, have a single table indexed by IfDirection.  The only attribute 
>in this table would be a RowPointer to the row describing the first thing 
>to do to packets traveling in that direction.  In the case where the 

Does this proposal adequately allow a query agent to establish which direction
of traffic is operated upon by a TCB?

Do you really mean "indexed by IF direction"? Surely there are only
two values in this index, IN and OUT.

regards,

    Geoff Huston

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From: "Joel M. Halpern" <[email-masked]>
Date: Mon, 31 Jul 2000 20:29:48 -0400

There are indeed only two directions, and therefore only two rows in the 
table I am proposing.

As for determining which direction a TCB works in, I am not sure that is a 
useful question.  Given a TCB somewhere in the middle of a chain (not the 
beginning), asking "what direction does this work on" is generally less 
important than "what subset of the traffic will get handed to this".  If 
you have enough information to answer that question, you can determine 
easily what direction that is in.  One could view this (IfDirection in each 
table) as a simpler way to answer that question.  But we usually have an 
approach that tries to make sure that we really have use for attributes 
before throwing them in to simplify a question we might want to ask.
(By the way, the current structure makes it very hard for a human reader to 
figure out what the "first" think done to a packet in each direction 
is.  It can be determined, but it is not simple.)

Yours,
Joel M. Halpern

At 10:18 AM 8/1/00 +1000, Geoff Huston wrote:

>>I would like to suggest that IfDirection be removed from all of the 
>>tables where it now appears.
>>I believe that a side effect of this would be to remove any concern in 
>>the processing path about the falues used to identify different TCBs.
>
>