draft-ietf-tsvwg-sctp-udp-encaps-12.txt   draft-ietf-tsvwg-sctp-udp-encaps-13.txt 
Network Working Group M. Tuexen Network Working Group M. Tuexen
Internet-Draft Muenster Univ. of Appl. Sciences Internet-Draft Muenster Univ. of Appl. Sciences
Intended status: Standards Track R. R. Stewart Intended status: Standards Track R. R. Stewart
Expires: September 12, 2013 Adara Networks Expires: September 15, 2013 Adara Networks
March 11, 2013 March 14, 2013
UDP Encapsulation of SCTP Packets for End-Host to End-Host Communication UDP Encapsulation of SCTP Packets for End-Host to End-Host Communication
draft-ietf-tsvwg-sctp-udp-encaps-12.txt draft-ietf-tsvwg-sctp-udp-encaps-13.txt
Abstract Abstract
This document describes a simple method of encapsulating SCTP Packets This document describes a simple method of encapsulating SCTP Packets
into UDP packets and its limitations. This allows the usage of SCTP into UDP packets and its limitations. This allows the usage of SCTP
in networks with legacy NAT not supporting SCTP. It can also be used in networks with legacy NAT not supporting SCTP. It can also be used
to implement SCTP on hosts without directly accessing the IP-layer, to implement SCTP on hosts without directly accessing the IP-layer,
for example implementing it as part of the application without for example implementing it as part of the application without
requiring special privileges. requiring special privileges.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 12, 2013. This Internet-Draft will expire on September 15, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3.1. Portable SCTP Implementations . . . . . . . . . . . . . . 3 3.1. Portable SCTP Implementations . . . . . . . . . . . . . . 3
3.2. Legacy NAT Traversal . . . . . . . . . . . . . . . . . . 4 3.2. Legacy NAT Traversal . . . . . . . . . . . . . . . . . . 4
4. Unilateral Self-Address Fixing (UNSAF) Considerations . . . . 4 4. Unilateral Self-Address Fixing (UNSAF) Considerations . . . . 4
5. SCTP over UDP . . . . . . . . . . . . . . . . . . . . . . . . 4 5. SCTP over UDP . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. Architectural Considerations . . . . . . . . . . . . . . 4 5.1. Architectural Considerations . . . . . . . . . . . . . . 4
5.2. Packet Format . . . . . . . . . . . . . . . . . . . . . . 5 5.2. Packet Format . . . . . . . . . . . . . . . . . . . . . . 5
5.3. Encapsulation Procedure . . . . . . . . . . . . . . . . . 6 5.3. Encapsulation Procedure . . . . . . . . . . . . . . . . . 6
5.4. Decapsulation Procedure . . . . . . . . . . . . . . . . . 6 5.4. Decapsulation Procedure . . . . . . . . . . . . . . . . . 6
5.5. ICMP Considerations . . . . . . . . . . . . . . . . . . . 7 5.5. ICMP Considerations . . . . . . . . . . . . . . . . . . . 7
5.6. Path MTU Considerations . . . . . . . . . . . . . . . . . 7 5.6. Path MTU Considerations . . . . . . . . . . . . . . . . . 7
5.7. Handling of Embedded IP-addresses . . . . . . . . . . . . 7 5.7. Handling of Embedded IP-addresses . . . . . . . . . . . . 8
5.8. ECN Considerations . . . . . . . . . . . . . . . . . . . 8 5.8. ECN Considerations . . . . . . . . . . . . . . . . . . . 8
6. Socket API Considerations . . . . . . . . . . . . . . . . . . 8 6. Socket API Considerations . . . . . . . . . . . . . . . . . . 8
6.1. Get or Set the Remote UDP Encapsulation Port Number 6.1. Get or Set the Remote UDP Encapsulation Port Number
(SCTP_REMOTE_UDP_ENCAPS_PORT) . . . . . . . . . . . . . . 8 (SCTP_REMOTE_UDP_ENCAPS_PORT) . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 9 10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 10 10.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
This document describes a simple method of encapsulating SCTP packets This document describes a simple method of encapsulating SCTP packets
into UDP packets. SCTP as defined in [RFC4960] runs directly over into UDP packets. SCTP as defined in [RFC4960] runs directly over
IPv4 or IPv6. There are two main reasons for encapsulating SCTP IPv4 or IPv6. There are two main reasons for encapsulating SCTP
packets: packets:
o Allow SCTP traffic to pass through legacy NATs, which do not o Allow SCTP traffic to pass through legacy NATs, which do not
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encapsulation port number of the SCTP stack, the destination port encapsulation port number of the SCTP stack, the destination port
MUST be the remote UDP encapsulation port number stored for the MUST be the remote UDP encapsulation port number stored for the
association and the destination address to which the packet is sent association and the destination address to which the packet is sent
(see Section 5.1). (see Section 5.1).
Because the SCTP packet is the UDP payload, the length of the UDP Because the SCTP packet is the UDP payload, the length of the UDP
packet MUST be the length of the SCTP packet plus the size of the UDP packet MUST be the length of the SCTP packet plus the size of the UDP
header. header.
The SCTP checksum MUST be computed and the UDP checksum SHOULD be The SCTP checksum MUST be computed and the UDP checksum SHOULD be
computed (see [RFC5405] and [I-D.ietf-6man-udpzero] for UDP checksum computed for IPv4 (see [RFC0768]) and IPv6 (see [RFC2460] and
considerations). [I-D.ietf-6man-udpzero]). Although UDP with a zero checksum over
IPv6 is allowed under certain constraints [I-D.ietf-6man-udpzero],
this document does not specify mechanisms for this mode. Deployed
support may be limited and at the time of writing, the use of a zero
UDP checksum would also be counter to the goal of legacy NAT
traversal.
5.4. Decapsulation Procedure 5.4. Decapsulation Procedure
When an encapsulated packet is received, the UDP header is removed. When an encapsulated packet is received, the UDP header is removed.
Then the generic lookup is performed, as done by an SCTP stack Then the generic lookup is performed, as done by an SCTP stack
whenever a packet is received, to find the association for the whenever a packet is received, to find the association for the
received SCTP packet. After finding the SCTP association (which received SCTP packet. After finding the SCTP association (which
includes checking the verification tag), the UDP source port MUST be includes checking the verification tag), the UDP source port MUST be
stored as the encapsulation port for the destination address the SCTP stored as the encapsulation port for the destination address the SCTP
packet is received from (see Section 5.1). packet is received from (see Section 5.1).
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Kozuka, "Stream Control Transmission Protocol (SCTP) Kozuka, "Stream Control Transmission Protocol (SCTP)
Dynamic Address Reconfiguration", RFC 5061, September Dynamic Address Reconfiguration", RFC 5061, September
2007. 2007.
10.2. Informative References 10.2. Informative References
[RFC3424] Daigle, L. IAB, "IAB Considerations for UNilateral Self- [RFC3424] Daigle, L. IAB, "IAB Considerations for UNilateral Self-
Address Fixing (UNSAF) Across Network Address Address Fixing (UNSAF) Across Network Address
Translation", RFC 3424, November 2002. Translation", RFC 3424, November 2002.
[RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines
for Application Designers", BCP 145, RFC 5405, November
2008.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA) Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165, RFC Transport Protocol Port Number Registry", BCP 165, RFC
6335, August 2011. 6335, August 2011.
[RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V. [RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V.
Yasevich, "Sockets API Extensions for the Stream Control Yasevich, "Sockets API Extensions for the Stream Control
Transmission Protocol (SCTP)", RFC 6458, December 2011. Transmission Protocol (SCTP)", RFC 6458, December 2011.
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