Subject: Protocol Action: Stream Control Transmission Protocol to Proposed Standard

From: The IESG <[email-masked]>
Date: Thu, 13 Jul 2000 19:29:21 -0400

The IESG has approved the Internet-Draft 'Stream Control Transmission
Protocol' <draft-ietf-sigtran-sctp-13.txt> as a Proposed Standard.
This document is the product of the Signaling Transport Working Group.
The IESG contact persons are Scott Bradner and Allison Mankin.

Technical Summary
 
  The Stream Control Transmission Protocol (SCTP) is designed to transport
  PSTN signaling messages over IP networks, but is capable of supporting other
  applications.

  SCTP is a reliable datagram transfer protocol operating on top of IP. It
  offers the following services to its users:

  -- acknowledged error-free non-duplicated transfer of user data,
  -- data segmentation to conform to discovered path MTU size,
  -- sequenced delivery of user messages within multiple streams,
     with an option for order-of-arrival delivery of individual
     user messages,
  -- optional multiplexing of user messages into SCTP datagrams, and
  -- network-level fault tolerance through supporting of multi-homing
     at either or both ends of an association.

  The design of SCTP includes appropriate congestion avoidance behavior and
  resistance to flooding and masquerade attacks.

  SCTP was developed to provide an alternative to TCP in some applications
  where TCP is seen as having some limitations:

   -- TCP provides both reliable data transfer and strict order-
      of-transmission delivery of data. Some applications need reliable
      transfer without sequence maintenance, while others would be
      satisfied with partial ordering of the data. In both of these
      cases the head-of-line blocking offered by TCP causes
      unnecessary delay.

   -- The stream-oriented nature of TCP is often an inconvenience.
      Applications must add their own record marking to delineate
      their messages, and must make explicit use of the push facility
      to ensure that a complete message is transferred in a
      reasonable time.

   -- The limited scope of TCP sockets complicates the task of
      providing highly-available data transfer capability using
      multi-homed hosts.

   -- TCP is relatively vulnerable to denial of service attacks,
      such as SYN attacks.

  Transport of PSTN signaling across the IP network is an application for
  which all of these limitations of TCP are relevant. While this application
  directly motivated the development of SCTP, other applications may find SCTP
  a good match to their requirements.

Working Group Summary

  There was some disagreement during IETF last call but the working group
  consensus supports this proposal.

Protocol Quality

 This proposal was reviewed for the IESG by Vern Paxson.