Subject: Explicit Rate flow control in IP.

From: Mahadevan Iyer <[email-masked]>
Date: Tue, 16 May 2000 05:26:00 -0700 (PDT)

I was curious to know why support or a standard for explicit rate flow
control to be provided by ISP's has not been considered in IETF yet.
I hope this general list is the best suited to posting my message.

As we well know, even simple scalable explicit rate protocols similar to
EPRCA or ERICA, to a mention a few, can lead to drastic improvements in
control of queue size, link utilization and fairness at congested ISP 
cores.
This in turn could lead to a noticeable improvement in download time for
Web pages and other multimedia transfers to name some simple examples. 

How to use the IP packet header to designate if it is a forward/backward
Control packet or not and also to carry control information such as
Explicit Rate, Queue Length, etc? Possibly, carry such detailed 
information as payload? After all, Control packets will only arrive only
once a 'while'. I haven't careful thought to this yet.

There are ways in which an IP router can estimate the fair share
(or even the max-min fair share) of available link bandwidth without
having to use *any*  kind of per-flow information. 

Since the flow control computation needed is per-Control-packet and not
per-data-packet, it should be feasible in most routers. 
          
Of course, the full benefits of explicit rate control will be realized
only if the route for a flow remains fixed. Maintaining such fixed routes
is possible in MPLS networks.

Maybe I am missing some crucial reason, why IETF standards for such
explicit rate control are not advisable..

Mahadevan.