Network Working Group M. Tuexen Internet-Draft Muenster Univ. of Applied Sciences Intended status: Informational R. Stewart Expires: May 26, 2007 Cisco Systems, Inc. November 22, 2006 UDP Encapsulation of SCTP Packets draft-tuexen-sctp-udp-encaps-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on May 26, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document describes a simple method of encapsulating SCTP Packets. This makes it possible to use SCTP in networks with legacy NAT not supporting SCTP. Tuexen & Stewart Expires May 26, 2007 [Page 1] Internet-Draft UDP Encapsulation of SCTP Packets November 2006 Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 Port Number Table . . . . . . . . . . . . . . . . . . . . . . . 3 4 Encapsulating procedures . . . . . . . . . . . . . . . . . . . . 4 5 Decapsulating procedures . . . . . . . . . . . . . . . . . . . . 4 6 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 7 Security Considerations . . . . . . . . . . . . . . . . . . . . 5 8 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 9.1 Normative References . . . . . . . . . . . . . . . . . . . . 5 9.2 Informative References . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Intellectual Property and Copyright Statements . . . . . . . . . . 7 Tuexen & Stewart Expires May 26, 2007 [Page 2] Internet-Draft UDP Encapsulation of SCTP Packets November 2006 1 Introduction This document describes a simple method of encapsulating SCTP Packets. This makes it possible to use SCTP in networks with legacy NAT not supporting SCTP. This described method interworks without any problems with the NAT mechanism described in SCTP_NAT [3]. For general NAT considerations regarding SCTP see SCTP_NAT_CONS [2]. 2 Architecture The basic architecture is shown in the following figure. +----------------+ +----------------+ | Encapsulating/ | | Encapsulating/ | +-| Decapsulating |---| Decapsulating |-+ | | Point | | Point | | +----------+ | +----------------+ +----------------+ | +----------+ | |-+ +-| | | SCTP | | SCTP | | Endpoint | | Endpoint | | |-+ +-| | +----------+ | +----------------+ +----------------+ | +----------+ | | Encapsulating/ | | Encapsulating/ | | +-| Decapsulating |---| Decapsulating |-+ | Point | | Point | +----------------+ +----------------+ On each path there is a pair of encapsulating/decapsulating points (EDPs). When the left SCTP endpoint sends an SCTP packet to the right SCTP endpoint, the first EDP on the path encapsulates the SCTP packet and the second EDP decapsulates it. Between the EDP a UDP packet is sent which can be processed by legacy NATs. The EDPs on different paths do not need to be synchronized. 3 Port Number Table Every EDP maintains an encapsulating table (ET) where each row consists of the following entries: 1. Source Address 2. Source Port 3. Destination Address Tuexen & Stewart Expires May 26, 2007 [Page 3] Internet-Draft UDP Encapsulation of SCTP Packets November 2006 4. Destination Port 5. Time Stamp Please note that the port numbers in the ET are used to build the UDP header while encapsulating. A row SHOULD be deleted when the time stamp is older than T1 seconds. The default value for T1 is 300 seconds. 4 Encapsulating procedures When an EDP has to encapsulate an SCTP packet it looks up the source and destination port number in the row with matching source and destination addresses of the ET. If no matching row is found, the IANA registered value 9899 is used for the source and destination port as the result of the lookup procedure. If a matching row was found, the time stamp of that row is set to the current time. The EDP inserts then an UDP header between the IP and SCTP header of the SCTP packet using the source port and the destination port from the above lookup procedure. Furthermore the length and the checksum field of the UDP header have to be set accordingly. Finally the IP header is updated to indicate that it now encapsulates an UDP packet. 5 Decapsulating procedures When an EDT has to decapsulate an SCTP packet, it removes the UDP header from the packet. The IP header is updated to indicate that it now encapsulates an SCTP packet. If the source and destination port numbers are not both equal to 9899, the EDP performs a lookup in the ET to find a row with the source address of the packet being the destination address in the row and the destination address of the packet being the source address in the row. If such a row is found, the port numbers are updated. If no row is found, a new one is created using the addresses and the port numbers from the packet by exchanging the source and destination information. In both cases the time stamp of the row is set to the current time. 6 IANA Considerations This document does not require any actions from IANA. Tuexen & Stewart Expires May 26, 2007 [Page 4] Internet-Draft UDP Encapsulation of SCTP Packets November 2006 7 Security Considerations This section is not complete yet. 8 Acknowledgments The authors wish to thank Irene Ruengeler for her invaluable comments. 9. References 9.1. Normative References [1] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M., Zhang, L., and V. Paxson, "Stream Control Transmission Protocol", RFC 2960, October 2000. 9.2. Informative References [2] Xie, Q., "SCTP NAT Traversal Considerations", draft-xie-behave-sctp-nat-cons-01 (work in progress), October 2005. [3] Stewart, R. and M. Tuexen, "Stream Control Transmission Protocol (SCTP) Network Address Translation", draft-stewart-behave-sctpnat-02 (work in progress), May 2006. Authors' Addresses Michael Tuexen Muenster Univ. of Applied Sciences Stegerwaldstr. 39 48565 Steinfurt Germany Email: tuexen@fh-muenster.de Tuexen & Stewart Expires May 26, 2007 [Page 5] Internet-Draft UDP Encapsulation of SCTP Packets November 2006 Randall R. Stewart Cisco Systems, Inc. 4875 Forest Drive Suite 200 Columbia, SC 29206 USA Email: rrs@cisco.com Tuexen & Stewart Expires May 26, 2007 [Page 6] Internet-Draft UDP Encapsulation of SCTP Packets November 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Tuexen & Stewart Expires May 26, 2007 [Page 7]