Subject: [Sigtran] question on SCTP future work

From: "Parmar, Pankaj N" <[email-masked]>
Date: Mon, 25 Feb 2002 11:18:04 -0800

Currently SCTP supports multihoming which could be used as a mechanism to
achieve fault-tolerance, but not load-balancing. Has any thought being given
to extending SCTP to support load-balancing ? Any folks working on it or
thinking about it ?

Thanks,

-Pankaj

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 25 Feb 2002 14:08:50 -0600

Pankaj,

We already have load-balancing in our route selection algoritm in our
GPL'ed implementation of SCTP.  It is a rather straightforward thing
to do.  Our algorithm is based on choosing the destination with the
largest available window on each outgoing SCTP packet.

Nevertheless, in general the impact of such an approach on the
efficiency of the underlying network and the impact on the receiving
peer is rather network specific.  For example, load sharing across
multiple destinations may significantly increase the probability that
packet arrive out of order placing a heavier demand on the receiver
to perform the reordering.  It is fairly apparent and there are a
number of arguments that show that the RFC 2960 approach (send to
primary address) is the best approach for the big I.

Therefore, in our implementation load balancing is turned off.

What did you hope to acheive with load balancing which is already
acheived by fail-over between destinations?  Better fail-over
performance?

If you objective is better fail-over performance, Another approach
which has negative impacts on the receiver but significantly increases
fail-over performance is to send a copy of each SCTP packet to each
destination (sort of a broadcast).  This increases redundancy to a
per-packet basis and ensures 0 fail-over times.  However, the receiving
SCTP peer has a heavy job performing reordering and handling duplicate
TSNs.

Both approaches have a negative impact on bandwidth utilization and
performance of the receiving SCTP peer.

What did you hope to acheive with load balancing?

--brian

Parmar, Pankaj N wrote:                                   (Mon, 25 Feb 2002 11:18:04)

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/