Subject: [Tsvwg] SCTP and HOL blocking: number of SCTP streams to use

From: Sebastian Kiesel <[email-masked]>
Date: Fri, 29 Sep 2006 16:20:43 +0200

Dear all,

in the last few months there have been several new Internet Drafts and
RFCs on how to transport a given signaling protocol over SCTP, such as
DIAMETER, MEGACO/H.248, NSIS/GIST, or SIMCO. Many of them specify to use
several SCTP streams in order to reduce the delaying effect of
head-of-line blocking. However, there are hardly any guidelines
available concerning the number of streams to choose when implementing
these specifications (of course, for a protocol specification, it is
reasonable to consider this parameter to be implementation specific
or a matter of configuration; nevertheless the programmers or
administrators need some advice with respect to it.)

We have conducted both analytical studies as well as measurements on a
"SIMCO over SCTP" prototype implementation, in order to quantify the
advantages of SCTP multistreaming, compared to TCP with respect to
application-layer transaction delays caused by packet loss and
head-of-line blocking. We also show that usually a rather small
number of streams can completely avoid head-of-line blocking.
For further information please see:

http://www.ikr.uni-stuttgart.de/Content/Publications/View/Standalone/FullRecord.html?36482

http://www.ikr.uni-stuttgart.de/Content/Publications/View/Standalone/FullRecord.html?36515

SIMCO [RFC 4540] is a rather lightweight, transaction based protocol for
controlling firewalls and NATs. Depending on the deployment scenario
(e.g., firewalls at the interconnection of large VoIP networks)
signaling load may be rather high. While this protocol is primarily a
concern of the MIDCOM WG the studies on SCTP based transport might be of
interest here as well. How to transport SIMCO over SCTP has been
specified by us in an Internet Draft, see the announcement below.
Changes compared to previous versions of this Internet Draft are only
minor, clarifying one special case, fixing a typo, adding the
identifiers and port numbers registered with IANA, and updating the
references. 

Any comments are welcome.

Thanks,
   Sebastian

-- 
Sebastian Kiesel                University of Stuttgart
Tel: +49 711 685 69017          Institute of Communication Networks and
Fax: +49 711 685 67983          Computer Engineering (IKR, formerly: IND)
[email-masked]     Pfaffenwaldring 47, 70569 Stuttgart, Germany

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To: [email-masked]
Cc: 
From: [email-masked]
Date: Tue, 26 Sep 2006 10:50:01 -0400
Subject: I-D ACTION:draft-kiesel-midcom-simco-sctp-02.txt 
Reply-To: [email-masked]

A New Internet-Draft is available from the on-line Internet-Drafts 
directories.

	Title		: SIMCO over SCTP
	Author(s)	: S. Kiesel
	Filename	: draft-kiesel-midcom-simco-sctp-02.txt
	Pages		: 13
	Date		: 2006-9-26
	
This document specifies how to use SCTP for the transport of the
SIMCO (Version 3.0) protocol.  SIMCO (SImple Middlebox COnfiguration)
is a protocol that implements the MIDCOM semantics.  It can be used
for controlling middleboxes such as firewalls and network address
translators.  SCTP (Stream Control Transmission Protocol) is a
transport layer protocol that is expected to have advantages for this
type of application, compared to TCP, which is the default transport
layer protocol for SIMCO.  The specific requirements for SIMCO when
using SCTP instead of TCP are specified in this document.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-kiesel-midcom-simco-sctp-02.txt

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