Internet DRAFT - draft-tuexen-tsvwg-sctp-init-fwd
draft-tuexen-tsvwg-sctp-init-fwd
Network Working Group M. Tüxen
Internet-Draft T. Völker
Intended status: Standards Track Münster Univ. of Appl. Sciences
Expires: 10 April 2024 8 October 2023
INIT Forwarding for the Stream Control Transmission Protocol
draft-tuexen-tsvwg-sctp-init-fwd-02
Abstract
The Stream Control Transmission Protocol (SCTP) extension described
in this document allows the support of a simple mechanism to
distribute association requests between a cluster of SCTP end points
providing the same service. In particular, this allows the use of
anycast addresses in combination with SCTP.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 10 April 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. A New Chunk Parameter . . . . . . . . . . . . . . . . . . . . 2
4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Socket API Considerations . . . . . . . . . . . . . . . . . . 4
5.1. Get or Set Accepting a Zero Checksum
(SCTP_INIT_FORWARDING) . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
The protocol extension described in this document allows an
initiation of an SCTP association to deal with an address change of
the peer during the handshake. The extension enables the peer to
respond from another address than the one used as destination address
in the received packet containing the INIT chunk. The SCTP Dynamic
Address Reconfiguration extension described in [RFC5061] can not be
used, since it does not apply to the handshake.
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. A New Chunk Parameter
The INIT Forwarding Chunk Parameter is defined by the following
figure.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x8006 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ \
/ Parameter /
\ \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 1: INIT Forwarding Chunk Parameter
Type: 16 bits (unsigned integer)
This field holds the IANA defined parameter type for the "INIT
Forwarding" chunk parameter. IANA is requested to assign the
value 32774 (0x8006) for this parameter type.
Length: 16 bits (unsigned integer)
This field holds the length in bytes of the chunk parameter; the
value MUST be the length of the parameter included plus 4.
Parameter: variable length
The parameter MUST be one of:
* IPv4 Address parameter as specified in [RFC9260].
* IPv6 Address parameter as specified in [RFC9260].
* Padding parameter as specified in [RFC4820]. The length of the
Padding parameter MUST be either the length of an IPv4 Address
parameter or the length of the IPv6 Address parameter.
All transported integer numbers are in "network byte order" a.k.a.,
Big Endian.
The INIT Forwarding Chunk Parameter MAY appear in INIT and INIT ACK
chunks and MUST NOT appear in any other chunk. If an INIT or INIT
ACK chunk contains an INIT Forwarding Chunk Parameter, the INIT
Forwarding Chunk Parameter MUST be the first optional/variable-length
parameter.
If an end point not supporting the extension described in this
document receives this parameter in an INIT or INIT ACK chunk, it
skips this parameter and continues to process further parameters in
the chunk. This behaviour is REQUIRED by [RFC9260] because the
highest-order 2 bits of the Type are 10.
4. Procedures
If an end point that sends an SCTP packet containing an INIT chunk
wants to allow the peer to respond from an address different from the
destination address of the packet, MUST use the INIT Forwarding Chunk
parameter as the first optional/variable-length parameter. The
parameter in the INIT Forwarding Chunk parameter MUST be a Padding
parameter. If the SCTP packet containing the INIT chunk is sent over
IPV4, the length of the padding parameter MUST be the length of an
IPv4 Address parameter, which is 8 bytes. Otherwise, if the SCTP
packet containing the INIT chunk is sent over IPV6, the length of the
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padding parameter MUST be the length of an IPv6 Address parameter,
which is 20 bytes.
If a middlebox receives an SCTP packet containing an INIT chunk with
INIT Forwarding Chunk parameter as its first optional/variable-length
parameter and wants to change the destination address of the packet,
it MUST replace the Padding parameter in the INIT Forwarding Chunk
parameter with an IPv4 or IPv6 Address parameter containing the
original destination address of the SCTP packet containing the INIT
chunk. If the INIT Forwarding Chunk parameter does not contain a
Padding parameter, but an IPv4 or IPv6 Address parameter, the INIT
Forwarding Chunk parameter MUST NOT be modified at all.
If an end point receives an SCTP packet containing an INIT chunk and
the INIT chunk contains an INIT Forwarding Chunk parameter including
an Address parameter as its first optional/variable-length parameter,
the end point MUST include this INIT Forwarding Chunk parameter as
the first optional/variable-length parameter in the INIT ACK chunk,
which is sent in response. If the INIT Forwarding Chunk parameter
contains a Padding parameter and the end-point does not want to use
the destination address, it MUST put an INIT Forwarding Chunk
parameter containing this address in the INIT ACK chunk sent in
response. If the end point wants to use the destination address in
the association and the INIT Forwarding Chunk parameter contains a
Padding parameter, the INIT Forwarding Chunk parameter MUST NOT be
included in the INIT ACK chunk.
If an end point receives an SCTP packet containing an INIT ACK chunk
and it cannot find the association for this packet using the IP
addresses and port numbers, and the INIT ACK chunk contains an INIT
Forwarding Chunk parameter as its first optional/variable-length
parameter, it SHOULD use the IP address contained in the Address
parameter of the INIT Forwarding Chunk parameter instead of the
source address of the received packet for the association lookup. If
an association is then found, the address in the INIT Forwarding
Chunk parameter MUST be removed as a remote address and the source
address of the packet containing the INIT ACK chunk MUST be added as
an unconfirmed remote address.
5. Socket API Considerations
This section describes how the socket API defined in [RFC6458] needs
to be extended to provide a way for the application to control the
UDP encapsulation.
Please note that this section is informational only.
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A socket API implementation based on [RFC6458] is extended by
supporting one new read/write IPPROTO_SCTP level socket option.
5.1. Get or Set Accepting a Zero Checksum (SCTP_INIT_FORWARDING)
This socket option can be used to control the support of INIT
forwarding. It applies only to future SCTP associations on the
socket.
This option expects an integer boolean flag, where a non-zero value
turns on the option, and a zero value turns off the option.
This option is off by default.
6. IANA Considerations
[NOTE to RFC-Editor: "RFCXXXX" is to be replaced by the RFC number
you assign this document.]
[NOTE to RFC-Editor: The requested value for the parameter type is
tentative and to be confirmed by IANA.]
This document (RFCXXXX) is the reference for the registration
described in this section.
A new chunk parameter type has to be assigned by IANA. This requires
an additional line in the "Chunk Parameter Types" registry for SCTP:
+==========+==========================+===========+
| ID Value | Chunk Parameter Type | Reference |
+==========+==========================+===========+
| 32774 | INIT Forwarding (0x8006) | [RFCXXXX] |
+----------+--------------------------+-----------+
Table 1: New entry in "Chunk Parameter Types"
registry
7. Security Considerations
This document does not change the considerations given in [RFC9260].
8. References
8.1. Normative References
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[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>.
[RFC4820] Tuexen, M., Stewart, R., and P. Lei, "Padding Chunk and
Parameter for the Stream Control Transmission Protocol
(SCTP)", RFC 4820, DOI 10.17487/RFC4820, March 2007,
<https://www.rfc-editor.org/info/rfc4820>.
[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
[RFC5061] Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M.
Kozuka, "Stream Control Transmission Protocol (SCTP)
Dynamic Address Reconfiguration", RFC 5061,
DOI 10.17487/RFC5061, September 2007,
<https://www.rfc-editor.org/info/rfc5061>.
[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>.
Authors' Addresses
Michael Tüxen
Münster University of Applied Sciences
Stegerwaldstrasse 39
48565 Steinfurt
Germany
Email: tuexen@fh-muenster.de
Timo Völker
Münster University of Applied Sciences
Stegerwaldstrasse 39
48565 Steinfurt
Germany
Email: timo.voelker@fh-muenster.de
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