Subject: Re: differential services tos octet

From: Indra Widjaja <[email-masked]>
Date: Fri, 17 Oct 1997 17:25:03 -0400

At 12:15 PM 10/17/97 -0700, Steve Deering wrote:
>At 12:26 AM -0700 10/17/97, Juha Heinanen wrote:
>> steve's argument about where the extra traffic should be dropped has
>> been going on long time also on other forums than ietf.  abr keeps
>> congestion out of the atm core and causes packets to be buffered and
>> dropped at the edge routers, whereas ubr allows all traffic up to a
>> certain peak rate into the core and then drops extra packets fairly at
>> the congestion points inside the network.
>
>Is ABR the one that uses hop-by-hop flow control to push congestion
>back towards the source?  I am most emphatically *not* advocating
>hop-by-hop flow control for the Internet!

No, it is end-to-end. But the source/destination can be an
intermediate node (virtual source/dest). ABR is designed so that the
source node can throttle its rate. But if the source is a router (as Juha
explained above; please correct me if I'm wrong), it can't throttle its
rate so that congestion will build up there.
Recent work by others suggest that UBR+EPD is better (i.e., achieves
higher goodput) than ABR. 
Is this assertion correct?

indra

---

From: Paul Ferguson <[email-masked]>
Date: Fri, 17 Oct 1997 20:02:40 -0400

>No, it is end-to-end. But the source/destination can be an

End-to-end is relative. ABR flow-control is only 'end-to-end'
from ingress to egress in the ATM network.

>Is this assertion correct?

You decide. A good resouce on this issue is:

 End-to-End Traffic Management Issues in IP/ATM Internetworks
 draft-jagan-e2e-traf-mgmt-00.txt
 S. Jagannath and N. Yin
 August 1997

- paul

---

From: LORCY Yann-Olivier <[email-masked]>
Date: Thu, 23 Oct 1997 11:11:59 +0200

I have missed the beginning of this discussion on differential services,
and I am now interested in this subject. Does anyone know if there is an
archive of this mailing list, where I will be able to find the whole
discussion.

Thanks

Yann-Olivier LORCY

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