Subject: Receiver control of the access link

From: Borje Ohlman <[email-masked]>
Date: Fri, 14 Nov 1997 16:17:41 +0100

On the issue of receiver control I agree with those who claim that we
in this first version of differentiated services should limit the
mechanism to sender control. If you are not happy with the network
throughput from a source you are receiving traffic from you have to
have the source solve this with its ISP.

BUT, even though I think we should restrain ourselves from the temptation
to try to provide receiver control in the *network* I think there are
compelling reasons to give the receiver control over its *access link*.
E.g. if you are on a narrow access link and having a prioritized voice
"connection" with someone, you might not want it spoiled by some third
party who just decided to send a large data file to you using a
prioritized FTP connection. Especially this will be of great importance to

a rapidly growing community of wireless connected Internet users.

To give the receiver control over which flows it values most we suggest
that the semantics of the priority bits is changed across the receivers
access link, compared to within the network. Instead of defining the
priority over the receiver access link they will be regarded as a request.

This will mean that the receiver access node will ignore the priority bits

when the first packet in a flow arrives (i.e. treat it as OUT). It will
not grant priority before it receives a priority ack message from the user

terminal. This requires a new (very simple) protocol to be defined between
the user and its accessnode.

This gives the user the power to control the incoming traffic on his
access link. This do require per flow state in the receiver access node.
The states will be soft states, which means that the user has to renew the

ack message periodically. As the priorities are kept as soft states the
user can revoke them simply by not sending any more acks.

The amount of traffic dropped in an overload situation is the same with or

without this mechanism, the difference is that this gives the
receiver a better chance of influencing which traffic is dropped.

Regards,
        Börje Ohlman

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Börje Ohlman
KK/ERA/T/NI  (Network Reference Group (NRG) @ Switchlab)
Ericsson Radio                            Tel.   +46- 8-719 3187
Dialoggatan 1  (Kungens Kurva)            Mobil. +46-70-519 3187
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