Internet DRAFT - draft-tuexen-tsvwg-sctp-ppid-frag
draft-tuexen-tsvwg-sctp-ppid-frag
Network Working Group M. Tüxen
Internet-Draft Münster Univ. of Appl. Sciences
Intended status: Standards Track R. Jesup
Expires: 9 June 2024 Mozilla
H. Tschofenig
7 December 2023
Payload Protocol Identifier based Fragmentation and Reassembly for the
Stream Control Transmission Protocol
draft-tuexen-tsvwg-sctp-ppid-frag-00
Abstract
This document describes a method for the Stream Control Transmission
Protocol (SCTP) allowing the upper layer to perform fragmentation,
reassembly, and interleaving of large ordered user messages by using
the payload protocol identifier (PPID).
According to the base specification supporting fragmentation of large
user messages is optional. And even if an SCTP implementation
supports fragmentation, interleaving of user messages is not
supported by the base specification.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 9 June 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Sender Side Considerations . . . . . . . . . . . . . . . . . 3
4. Receiver Side Considerations . . . . . . . . . . . . . . . . 3
5. Socket API Considerations . . . . . . . . . . . . . . . . . . 3
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
8.1. Normative References . . . . . . . . . . . . . . . . . . 4
8.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
This document specifies a method to use PPIDs for fragmenting ordered
large user messages. Using this method also allows the ability to
interleave large user messages as provided by [RFC8260] in
combination with using the SCTP_FRAGMENT_INTERLEAVE level_2 as
described [RFC6458], Section 8.1.20.
Reasons to use this method include:
* The fragmentation of large user messages is only an optional
feature of SCTP implementations compliant [RFC9260]. Therefore,
if an implementation does not support fragmentation, it is
impossible to send large user messages requiring fragmentation.
* An SCTP implementation supporting [RFC9260], but not [RFC8260],
does not allow the interleaving of large user messages.
This method does not apply to user messages sent using partial
reliability as described in [RFC3758].
The idea described in this document was already described in
[I-D.ietf-rtcweb-data-channel]. In the final specification
[RFC8831], this method is declared deprecated.
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2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Sender Side Considerations
An upper layer splits a user message in one or more user message
fragments. The upper layer SHOULD choose the size of the user
message fragments such than SCTP level fragmentation is avoided.
The upper layer uses two PPIDs. It MUST use one PPID for all user
messages fragments except the last one, and it MUST the other PPID
for the last user message fragments.
All user message fragments belonging to the same user message MUST be
sent on the same stream, reliable, and ordered in the sequence they
belong to the user message. User message fragments sent on different
stream MAY be sent in any order. This allows the interleaving of
user messages sent on different streams.
User messages not requiring to be split into multiple user message
fragments are sent as a single user message fragment with the PPID
used for last user fragments.
4. Receiver Side Considerations
The upper layer MUST process user message fragments received on
different streams independently. All user message fragments are
received by the upper layer in the correct ordering and the PPID MUST
be used to reconstruct the user message boundaries. A user message
fragment with the PPID marking the last user message fragment is the
last fragment of a use message. The next received user message
fragment on the stream is the first fragment of the next user
message.
An upper layer MUST deal with interleaving of user messages.
Please note that notifications, if enabled, can be provided by the
SCTP implementation at any time.
5. Socket API Considerations
This document does not require and changes or additions to the Socket
API described in [RFC6458].
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6. IANA Considerations
This document does not make any requests for IANA.
7. Security Considerations
This document does not change the considerations given in [RFC9260].
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9260] Stewart, R., Tüxen, M., and K. Nielsen, "Stream Control
Transmission Protocol", RFC 9260, DOI 10.17487/RFC9260,
June 2022, <https://www.rfc-editor.org/info/rfc9260>.
8.2. Informative References
[I-D.ietf-rtcweb-data-channel]
Jesup, R., Loreto, S., and M. Tüxen, "WebRTC Data
Channels", Work in Progress, Internet-Draft, draft-ietf-
rtcweb-data-channel-06, 4 January 2015,
<https://datatracker.ietf.org/doc/html/draft-ietf-rtcweb-
data-channel-06>.
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
Conrad, "Stream Control Transmission Protocol (SCTP)
Partial Reliability Extension", RFC 3758,
DOI 10.17487/RFC3758, May 2004,
<https://www.rfc-editor.org/info/rfc3758>.
[RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V.
Yasevich, "Sockets API Extensions for the Stream Control
Transmission Protocol (SCTP)", RFC 6458,
DOI 10.17487/RFC6458, December 2011,
<https://www.rfc-editor.org/info/rfc6458>.
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[RFC8260] Stewart, R., Tuexen, M., Loreto, S., and R. Seggelmann,
"Stream Schedulers and User Message Interleaving for the
Stream Control Transmission Protocol", RFC 8260,
DOI 10.17487/RFC8260, November 2017,
<https://www.rfc-editor.org/info/rfc8260>.
[RFC8831] Jesup, R., Loreto, S., and M. Tüxen, "WebRTC Data
Channels", RFC 8831, DOI 10.17487/RFC8831, January 2021,
<https://www.rfc-editor.org/info/rfc8831>.
Authors' Addresses
Michael Tüxen
Münster University of Applied Sciences
Stegerwaldstrasse 39
48565 Steinfurt
Germany
Email: tuexen@fh-muenster.de
Randell Jesup
Mozilla Corporation
1835 Horse Shoe Trl
Malvern, PA 19355
United States of America
Email: randell-ietf@jesup.org
Hannes Tschofenig
Email: hannes.tschofenig@gmx.net
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