Subject: Re: [Diffserv] Terminology draft

From: [email-masked]
Date: Thu, 7 Oct 1999 11:07:18 -0400

Brian Carpenter wrote:
>       (snip) ...                             I observed that the word "group"
is
> recursive; there is no problem with the concept of a PHB Group
> that contains several PHB Groups.  One possible approach is to
> accept this view, agree that both Kathie and Dan are correct,
> and tweak the definition of PHB Group accordingly.

I think Brian's point makes a lot of sense.  I also like to generalize Dan's
definition of PHB Group Family  (using his terminology for the moment; otherwise
I'll have to invent something like Super Group...):

   PHB Group Family: A set of PHB groups which share the same definition and
   characteristics, and are specified together as a group.  Each PHB group can
   be viewed as an instance from the same PHB group template.  The number of
   such PHB groups (e.g., 1 to 4; or exactly 4) and the relationships among the
   PHB groups (e.g., Group n has higher priority over Group n+1; or no
   constraint) in the family are governed by the definition of the PHB Group
   Family.

Hence the 4 AF classes (with 3 DPs each) forms an PHB Group Family called
"Assured Forwarding"; and per the definitions in RFC 2475, there will be exactly
4 groups (AF1 to AF4), each independent of the other.  This does not prevent
people from defining other group families in the future that have some priority
ordering between member groups, if that turns out to be useful.

Liang.