Network Working Group M. Tuexen Internet-Draft Muenster Univ. of Applied Sciences Intended status: Standards Track R. Stewart Expires: April 19, 2007 P. Lei Cisco Systems, Inc. October 16, 2006 Padding Chunk and Parameter for SCTP draft-ietf-tsvwg-sctp-padding-02.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 April 19, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document defines a padding chunk and a padding parameter and describes the required receiver side procedures. The padding chunk is used to pad an SCTP packet to an arbitrary size. The padding parameter is used to pad an SCTP INIT chunk to an arbitrary size. Tuexen, et al. Expires April 19, 2007 [Page 1] Internet-Draft Padding Chunk and Parameter for SCTP October 2006 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Padding Chunk (PAD) . . . . . . . . . . . . . . . . . . . . . . 3 4. Padding Parameter (PAD) . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 5.1. A New Chunk Type . . . . . . . . . . . . . . . . . . . . . 5 5.2. A New Parameter Type . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 8 Tuexen, et al. Expires April 19, 2007 [Page 2] Internet-Draft Padding Chunk and Parameter for SCTP October 2006 1. Introduction This document defines a padding chunk and a padding parameter and describes the required receiver side procedures. The padding chunk is used to pad an SCTP packet to an arbitrary size. The padding parameter is used to pad an SCTP INIT chunk to an arbitrary size. The usage of the PAD chunk for path MTU discovery is described in PMTU [3]. The inappropriate usage of the PAD parameter or PAD chunk can result in wasted bandwidth. 2. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL", when they appear in this document, are to be interpreted as described in RFC2119 [1]. 3. Padding Chunk (PAD) This chunk is used to pad an SCTP packet. A PAD chunk can be used to enlarge the packet by 4 to 65536 bytes in steps of 4 bytes. An SCTP packet MAY contain multiple PAD chunks. 0 1 2 3 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 = 0x84 | Flags=0 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | \ Padding Data / / \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 Type: 1 byte (unsigned integer) This value MUST be set to 0x84 for all PAD-chunks. Flags: 1 byte (unsigned integer) This value SHOULD be set to zero on transmit and MUST be ignored on receipt. Length: 2 bytes (unsigned integer) This value holds the length of the Padding Data plus 4. Tuexen, et al. Expires April 19, 2007 [Page 3] Internet-Draft Padding Chunk and Parameter for SCTP October 2006 Padding Data: n bytes (unsigned integer) This holds the Padding Data. The Padding Data MUST be ignored by the receiver. The receiver of the PAD chunk MUST discard this chunk and continue processing the rest of the chunks in the packet. Please note that this is also the required processing behavior for any unknown chunk having the same highest order two bits of the type as the PAD chunk. 4. Padding Parameter (PAD) This parameter is used to pad an INIT chunk. A PAD parameter can be used to enlarge the INIT chunk by 4 bytes as the minimum to the maximum size of the INIT chunk in steps of 4 bytes. An INIT chunk MAY contain multiple PAD parameters. 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Parameter Type = 0x8005 | Parameter Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / / \ Padding Data \ / / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 Parameter Type: 2 bytes (unsigned integer) This value MUST be set to 0x8005. Parameter Length: 2 bytes (unsigned integer) This value holds the length of the Padding Data plus 4. The PAD parameter MAY be included only in the INIT chunk. It MUST NOT be included in any other chunk. The receiver of the PAD parameter MUST silently discard this parameter and continue processing the rest of the INIT chunk. This means that the size of the generated COOKIE parameter in the INIT-ACK MUST NOT depend on the existence of the PAD parameter in the INIT chunk. A receiver of a PAD parameter MUST NOT include the PAD parameter within any State Cookie parameter it generates. 5. IANA Considerations [NOTE to RFC-Editor: Tuexen, et al. Expires April 19, 2007 [Page 4] Internet-Draft Padding Chunk and Parameter for SCTP October 2006 "RFCXXXX" is to be replaced by the RFC number you assign this document. ] This document (RFCXXX) is the reference for all registrations described in this section. All registrations need to be listed in the document available at sctp-parameters [4]. The suggested changes are described below. 5.1. A New Chunk Type A chunk type for the PAD chunk has to be assigned by IANA. It is suggested to use the value given in Figure 1. This requires an additional line in the "CHUNK TYPES" table of sctp-parameters [4]: CHUNK TYPES ID Value Chunk Type Reference -------- ---------- --------- 132(0x84) Padding Chunk (PAD) [RFCXXXX] 5.2. A New Parameter Type A parameter type has to be assigned for the PAD parameter by IANA. It is suggested to use the values given in Figure 2. This requires a modification in the "CHUNK PARAMETER TYPES" table in sctp- parameters [4]: Add a new line to the "INIT Chunk Parameter Types" table: Chunk Parameter Type Value -------------------- ----- Padding 32773(0x8005) 6. Security Considerations This document does not add any additional security considerations in addition to the ones given in RFC2960 [2]. 7. Acknowledgments The authors wish to thank Matthew J. Zekauskas, and Lars Eggert for his invaluable comments. 8. References Tuexen, et al. Expires April 19, 2007 [Page 5] Internet-Draft Padding Chunk and Parameter for SCTP October 2006 8.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] 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. 8.2. Informative References [3] Mathis, M. and J. Heffner, "Packetization Layer Path MTU Discovery", draft-ietf-pmtud-method-10 (work in progress), September 2006. URIs [4] Authors' Addresses Michael Tuexen Muenster Univ. of Applied Sciences Stegerwaldstr. 39 48565 Steinfurt Germany Email: tuexen@fh-muenster.de Randall R. Stewart Cisco Systems, Inc. 4875 Forest Drive Suite 200 Columbia, SC 29206 USA Email: rrs@cisco.com Tuexen, et al. Expires April 19, 2007 [Page 6] Internet-Draft Padding Chunk and Parameter for SCTP October 2006 Peter Lei Cisco Systems, Inc. 955 Happfield Dr. Arlington Heights, IL 60004 US Phone: +1 773 695-8201 Email: peterlei@cisco.com Tuexen, et al. Expires April 19, 2007 [Page 7] Internet-Draft Padding Chunk and Parameter for SCTP October 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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