Network Working Group M. TuexenInternet-DraftRequest for Comments: 4820 Muenster Univ. of Applied SciencesIntended status:Category: Standards Track R. StewartExpires: April 19, 2007P. Lei Cisco Systems, Inc.October 16, 2006March 2007 Padding Chunk and Parameter forSCTP draft-ietf-tsvwg-sctp-padding-02.txtthe Stream Control Transmission Protocol (SCTP) Status ofthisThis MemoBy 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 ofThis document specifies an Internet standards track protocol for the InternetEngineering Task Force (IETF), its areas,community, andits working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents validrequests discussion and suggestions fora maximumimprovements. Please refer to the current edition ofsix monthsthe "Internet Official Protocol Standards" (STD 1) for the standardization state andmay 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 liststatus ofcurrent Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The listthis protocol. Distribution ofInternet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 19, 2007.this memo is unlimited. Copyright Notice Copyright (C) TheInternet Society (2006).IETF Trust (2007). Abstract This document defines a padding chunk and a padding parameter and describes the required receiver side procedures. The padding chunk is used to padan SCTPa Stream Control Transmission Protocol (SCTP) packet to an arbitrary size. The padding parameter is used to pad an SCTP INIT chunk to an arbitrary size. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Padding Chunk (PAD) . . . . . . . . . . . . . . . . . . . . . . 3 4. Padding Parameter (PAD) . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .45 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 . . . . . . . . . . . . . . . . . . 6Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 81. 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].[4]. 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 inRFC2119RFC 2119 [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 allPAD-chunks.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. 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 samehighest orderhighest-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: "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 registrationsneed to behave been listed in the document available at sctp-parameters[4].[3]. Thesuggestedchanges are described below. 5.1. A New Chunk Type A chunk type for the PAD chunk hasto bebeen assigned by IANA.It is suggested to use theThe valuegivenhas been assigned as described in Figure 1.This requires an additional line inThe following has been added to the "CHUNK TYPES" table of sctp-parameters[4]:[3]: CHUNK TYPES ID Value Chunk Type Reference -------- ---------- --------- 132(0x84) Padding Chunk (PAD)[RFCXXXX][RFC4820] 5.2. A New Parameter Type A parameter type hasto bebeen assigned for the PAD parameter by IANA.It is suggested to use the values givenThe value has been assigned as described in Figure 2.This requires a modification inThe following has been added to the "CHUNK PARAMETER TYPES" table in sctp- parameters[4]: Add a new line to the "INIT[3]: INIT Chunk ParameterTypes" table:Types Chunk Parameter Type Value -------------------- ----- Padding 32773(0x8005) 6. Security Considerations This document does not add any additional security considerationsin additionto the ones given inRFC2960RFC 2960 [2]. 7. Acknowledgments The authors wish to thank Matthew J.Zekauskas,Zekauskas and Lars Eggert forhistheir invaluable comments. 8. References 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] "IANA registry", <http://www.iana.org/assignments/sctp-parameters>. [4] Mathis, M. and J. Heffner, "Packetization Layer Path MTU Discovery",draft-ietf-pmtud-method-10 (work in progress), September 2006. URIs [4] <http://www.iana.org/assignments/sctp-parameters>RFC 4821, March 2007. Authors' Addresses Michael Tuexen Muenster Univ. of Applied Sciences Stegerwaldstr. 39 48565 Steinfurt GermanyEmail:EMail: tuexen@fh-muenster.de Randall R. Stewart Cisco Systems, Inc. 4875 Forest Drive Suite 200 Columbia, SC 29206 USAEmail:EMail: rrs@cisco.com Peter Lei Cisco Systems, Inc. 955 Happfield Dr. Arlington Heights, IL 60004 US Phone: +1 773 695-8201Email:EMail: peterlei@cisco.com Full Copyright Statement Copyright (C) TheInternet Society (2006).IETF Trust (2007). 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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