North American Network Operators Group

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Re: multi-homing fixes

  • From: Iljitsch van Beijnum
  • Date: Sat Sep 01 16:35:40 2001

On Sat, 1 Sep 2001, Joel Baker wrote:


> Me, I prefer to build a new car that's fully up to new design specs, rather
> than try to retrofit rocket boosters onto the old Studebaker. This isn't to
> claim, in any way, that "TCP is dead", mind you; but SCTP answers a fairly
> fundamental set of problems, with a different set of design goals than TCP
> and UDP were written for. Trying to mangle TCP to accomodate those goals
> seems likely to produce more confusion than viable code.

SCTP is a protocol designed to carry telephony signalling.

Being able to use multiple IP addresses per session is not something that
is inherently more appropriate for telephony signalling than for network
applications that use stream-based communication. It is a nice option to
have for any transport protocol.

So unless there is _another_ reason why SCTP is appropriate for a certain
application, it seems pretty clear to me that using TCP, which was
designed to work with the protocols we use on the Net, and is the
transport protocol applications expect, is much more appropriate.
Extending TCP to use multiple IP addresses is not a problem. TCP has been
extended in many ways in the past. And an experimental implementation has
been available for four years.

> As for the 'SCTP isn't backwards compatible with older TCP'
> claim... uhm, TCP isn't backwards compatible with UDP, either. Your point?

But nobody is proposing to have applications built for UDP run over TCP.

I'm not against implementing new protocols that aren't backward
compatible, but I'm merely saying that in this case the benefits are too
small. And comparing this to IPv6: how many people are using IPv6 today?
Sometimes it is necessary to forego backward compatibility, but that
decission should never be taken lightly.