Using Self-Delimiting Numeric Values in Protocols
RFC 6256
Document | Type |
RFC - Informational
(May 2011; No errata)
Was draft-irtf-dtnrg-sdnv (dtnrg RG)
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Last updated | 2015-10-14 | ||
Stream | IRTF | ||
Formats | plain text pdf html bibtex | ||
Stream | IRTF state | (None) | |
Consensus Boilerplate | Unknown | ||
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 6256 (Informational) | |
Telechat date | |||
Responsible AD | Ralph Droms | ||
IESG note | IRTF Submission. Elwyn Davies (elwynd@dial.pipex.com) is the document shepherd. | ||
Send notices to | (None) |
Internet Research Task Force (IRTF) W. Eddy Request for Comments: 6256 MTI Systems Category: Informational E. Davies ISSN: 2070-1721 Folly Consulting May 2011 Using Self-Delimiting Numeric Values in Protocols Abstract Self-Delimiting Numeric Values (SDNVs) have recently been introduced as a field type in proposed Delay-Tolerant Networking protocols. SDNVs encode an arbitrary-length non-negative integer or arbitrary- length bitstring with minimum overhead. They are intended to provide protocol flexibility without sacrificing economy and to assist in future-proofing protocols under development. This document describes formats and algorithms for SDNV encoding and decoding, along with notes on implementation and usage. This document is a product of the Delay-Tolerant Networking Research Group and has been reviewed by that group. No objections to its publication as an RFC were raised. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Research Task Force (IRTF). The IRTF publishes the results of Internet-related research and development activities. These results might not be suitable for deployment. This RFC represents the consensus of the Delay-Tolerant Networking Research Group of the Internet Research Task Force (IRTF). Documents approved for publication by the IRSG are not a candidate for any level of Internet Standard; see Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6256. Eddy & Davies Informational [Page 1] RFC 6256 Using SDNVs May 2011 Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Table of Contents 1. Introduction ....................................................2 1.1. Problems with Fixed-Value Fields ...........................3 1.2. SDNVs for DTN Protocols ....................................4 1.3. SDNV Usage .................................................5 2. Definition of SDNVs .............................................6 3. Basic Algorithms ................................................8 3.1. Encoding Algorithm .........................................8 3.2. Decoding Algorithm .........................................9 3.3. Limitations of Implementations ............................10 4. Comparison to Alternatives .....................................10 5. Security Considerations ........................................13 6. Acknowledgements ...............................................13 7. Informative References .........................................14 Appendix A. SDNV Python Source Code ...............................15 1. Introduction This document is a product of the Internet Research Task Force (IRTF) Delay-Tolerant Networking (DTN) Research Group (DTNRG). The document has received review and support within the DTNRG, as discussed in the Acknowledgements section of this document. This document begins by describing the drawbacks of using fixed-width protocol fields. It then provides some background on the Self- Delimiting Numeric Values (SDNVs) proposed for use in DTN protocols, and motivates their potential applicability in other networking protocols. The DTNRG has created SDNVs to meet the challenges it attempts to solve, and it has been noted that SDNVs closely resemble certain constructs within ASN.1 and even older ITU protocols, so the problems are not new or unique to DTN. SDNVs focus strictly on numeric values or bitstrings, while other mechanisms have been developed for encoding more complex data structures, such as ASN.1 Eddy & Davies Informational [Page 2] RFC 6256 Using SDNVs May 2011 encoding rules and Haverty's Message Services Data Transmission Protocol (MSDTP) [RFC0713]. Because of this focus, SDNVs can be quickly implemented with only a small amount of code. SDNVs are tersely defined in both the Bundle Protocol [RFC5050] andShow full document text