Subject: Re: New Internet Draft

From: Steven Berson <[email-masked]>
Date: Mon, 31 Mar 1997 09:59:33 -0800 (PST)

On Sun, 30 Mar 1997, Shai Herzog wrote:

> The draft states: 
>  "our approach provides for reduction of packet scheduler
>    state, packet classifier state, and setup protocol (e.g. RSVP) state"
> 
> Perhaps I am missing something, but I don't see how it can reduce 
> RSVP state. Consider the following example:
> 
>     ...................                    .....................
>     .                 .                    .                   .
>     .   S1------|     .                    .  |----------R1    .     
>     .           A-------B----------------C----D                .
>     .   S2------|     .                    .  |----------R2    .  
>     .                 .                    .                   .
>     ...................                    .....................
> 
> 
> Assuming two sessions: (S1,R1) and (S2,R2) are aggregated over B-C.
> [A] tags the packets for both S1 and S2 with T, and sends an aggregated 
> reservation to [D]. (fat pipe between [A] and [D] for all packets tagged
> as T).  What happens at D? How would D generate the Path messages 
> to be sent to R1 and R2 if it doesn't have details about S1 and S2?
> 
> I always thought that the aggregation was trivial but the 
> disaggregation at the other side was the real problem.
> 
> Shai

Shai,

I think one misunderstanding is about aggregating by regions, i.e.
full RSVP, classifier, and scheduler state are available at border
routers and normal integrated services processing can be done.  Thus
if C (and B) are interior routers in a region, there is no RSVP state,
only bounded scheduling and classifying state, and no need to do any
disaggregation.  RSVP messages are forwarded, though.  If instead, B
and C are border routers in different regions, then full RSVP,
classifying and scheduling are done, and the disaggregation is as
currently done.

Summarizing, the full integrated services details are available at
border routers and so disaggregation can be done, while no details are
needed in the interior of a region as no disaggregation is needed.

There also seems to be a misunderstanding about reservations.  There
is no ``aggregated reservation sent to [D] for all packets tagged as
T,'' so I am not sure how to answer this.

Steve