Subject: Critically compare the congestion control on TCP/IP and ATM?

From: Jianbo Huang <[email-masked]>
Date: Wed, 08 Mar 2000 22:57:35 +0800

Dear Sirs and Madams,

A friend of mine are working on the paper on "critically compare the 
congestion control on TCP/IP and ATM", and she ask me for help. But I do 
not get much idea on the "congestion control on ATM". So, is there anyone 
can give me any idea on this topic, while my friend and I processing on 
this? Thank you!

rgds,

Sincerely yours,
Jianbo Huang

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From: "Andrew G. Malis" <[email-masked]>
Date: Wed, 08 Mar 2000 14:42:18 -0500

Jianbo,

See ftp://ftp.atmforum.com/pub/approved-specs/af-tm-0121.000.pdf, 
especially section 5.

Regards,
Andy

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At 10:57 PM 3/8/00 +0800, Jianbo Huang wrote:
>-
>This message was passed through [email-masked], which
>is a sublist of [email-masked]. Not all messages are passed.
>Decisions on what to pass are made solely by Harald Alvestrand.

________________________________________________________________________
Andrew G. Malis  [email-masked]  phone:978 952-7414  fax:978 392-2074
Lucent Technologies                 1 Robbins Road    Westford, MA 01886

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From: Fred Baker <[email-masked]>
Date: Fri, 10 Mar 2000 22:32:23 +1100

At 05:57 PM 3/9/00 +0800, Jianbo Huang wrote:
>can give me any idea on this topic, while my friend and I processing on this?

that's easy; there isn't any. There is ingress port policing, which is 
something different, and there may be PNNI call routing. But there is not 
anything that corresponds to what TCP expects from its underlying layers.

There have been some papers written and a fair bit of experience with a 
technique for mitigating this, called Early packet Discard. In essence, if 
a link is becoming congested, rather than dropping a single cell, if it has 
to drop an AAL5 cell it drops the entire packet containing the cell. This 
may sound odd, but it is actually quite sensible - if the other cells were 
not also dropped, then they would uselessly occupy bandwidth on subsequent 
links, and at the final delivery point would consume memory unnecessarily 
until the SAR was able to determine that the cell had been dropped.

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From: "Scott W Brim" <[email-masked]>
Date: Fri, 10 Mar 2000 11:04:03 -0500

ATM ABR offers explicit closed loop feedback about congestion experienced, and
will drop cells/frames if that feedback is not followed.  In certain types of VBR
the CLP bit can be used to indicate that a cell was out of profile.  Such cells do
not have to be dropped if the network has room for them.