--- 1/draft-ietf-manet-timetlv-07.txt 2008-09-26 20:12:22.000000000 +0200 +++ 2/draft-ietf-manet-timetlv-08.txt 2008-09-26 20:12:22.000000000 +0200 @@ -1,20 +1,20 @@ Mobile Ad hoc Networking (MANET) T. Clausen Internet-Draft LIX, Ecole Polytechnique, France Intended status: Standards Track C. Dearlove -Expires: March 20, 2009 BAE Systems Advanced Technology +Expires: March 30, 2009 BAE Systems Advanced Technology Centre - September 16, 2008 + September 26, 2008 Representing multi-value time in MANETs - draft-ietf-manet-timetlv-07 + draft-ietf-manet-timetlv-08 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 @@ -25,89 +25,134 @@ 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 March 20, 2009. + This Internet-Draft will expire on March 30, 2009. Abstract This document describes a general and flexible TLV (type-length-value - structure) for representing time using the generalized MANET packet/ - message format. It defines two message and two address block TLVs - for representing validity and interval times for MANET routing - protocols. + structure) for representing time-values, such as an interval or a + duration, using the generalized MANET packet/message format. It + defines two message and two address block TLVs for representing + validity and interval times for MANET routing protocols. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Motivation and Rationale . . . . . . . . . . . . . . . . . 3 - 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 3. Applicability Statement . . . . . . . . . . . . . . . . . . . 5 - 4. Protocol Overview and Functioning . . . . . . . . . . . . . . 5 - 5. Representing Time . . . . . . . . . . . . . . . . . . . . . . 5 - 6. General Time TLV Structure . . . . . . . . . . . . . . . . . . 6 - 6.1. Single-value Time TLVs . . . . . . . . . . . . . . . . . . 7 - 6.2. Multi-value Time TLVs . . . . . . . . . . . . . . . . . . 8 - 7. Message TLVs . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 7.1. INTERVAL_TIME TLV . . . . . . . . . . . . . . . . . . . . 9 - 7.2. VALIDITY_TIME TLV . . . . . . . . . . . . . . . . . . . . 9 - 8. Address Block TLVs . . . . . . . . . . . . . . . . . . . . . . 9 - 8.1. INTERVAL_TIME TLV . . . . . . . . . . . . . . . . . . . . 9 - 8.2. VALIDITY_TIME TLV . . . . . . . . . . . . . . . . . . . . 10 - 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 - 9.1. Expert Review: Evaluation Guidelines . . . . . . . . . . . 10 - 9.2. Message TLV Types . . . . . . . . . . . . . . . . . . . . 11 - 9.3. Address Block TLV Types . . . . . . . . . . . . . . . . . 11 - 10. Security Considerations . . . . . . . . . . . . . . . . . . . 12 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 11.1. Normative References . . . . . . . . . . . . . . . . . . . 12 - 11.2. Informative References . . . . . . . . . . . . . . . . . . 12 - Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 12 + 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 + 3. Applicability Statement . . . . . . . . . . . . . . . . . . . 6 + 4. Protocol Overview and Functioning . . . . . . . . . . . . . . 6 + 5. Representing Time . . . . . . . . . . . . . . . . . . . . . . 6 + 6. General Time TLV Structure . . . . . . . . . . . . . . . . . . 7 + 6.1. Single-value Time TLVs . . . . . . . . . . . . . . . . . . 8 + 6.2. Multi-value Time TLVs . . . . . . . . . . . . . . . . . . 9 + 7. Message TLVs . . . . . . . . . . . . . . . . . . . . . . . . . 10 + 7.1. INTERVAL_TIME TLV . . . . . . . . . . . . . . . . . . . . 10 + 7.2. VALIDITY_TIME TLV . . . . . . . . . . . . . . . . . . . . 10 + 8. Address Block TLVs . . . . . . . . . . . . . . . . . . . . . . 10 + 8.1. INTERVAL_TIME TLV . . . . . . . . . . . . . . . . . . . . 10 + 8.2. VALIDITY_TIME TLV . . . . . . . . . . . . . . . . . . . . 11 + 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 + 9.1. Expert Review: Evaluation Guidelines . . . . . . . . . . . 11 + 9.2. Message TLV Types . . . . . . . . . . . . . . . . . . . . 12 + 9.3. Address Block TLV Types . . . . . . . . . . . . . . . . . 12 + 10. Security Considerations . . . . . . . . . . . . . . . . . . . 13 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 + 11.1. Normative References . . . . . . . . . . . . . . . . . . . 13 + 11.2. Informative References . . . . . . . . . . . . . . . . . . 13 + Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 13 1. Introduction The generalized packet/message format [packetbb] specifies a signaling format which MANET routing protocols can employ for exchanging protocol information. This format presents the ability to express and associate attributes to packets, messages or addresses, by way of a general TLV (type-length-value) mechanism. This document specifies a general Time TLV structure, which can be used by any MANET routing protocol that needs to express either single time-values or a set of time-values with each time-value associated with a range of hop counts, as provided by the message header of [packetbb]. This allows a receiving node to determine a single time-value if either it knows its hop count from the originator node, or the Time TLV specifies a single time-value. + A time-value is, in this context, not an "absolute point in time", + but rather an interval or a duration. An instance of a Time TLV can, + therefore, express an interval or a duration such as "10 seconds". + This document also specifies two message TLV types, which use the TLV structure proposed. These TLV types are INTERVAL_TIME and VALIDITY_TIME, specifying respectively the maximum time before another message of the same type as this message from the same originator should be received, and the duration for which the information in this message is valid after receipt. Note that, if both are present, then the latter will usually be greater than the former in order to allow for possible message loss. This document also specifies two address block TLV types, which use the TLV structure proposed. These TLV types are INTERVAL_TIME and VALIDITY_TIME, defined equivalently to the two message TLVs with the same names. 1.1. Motivation and Rationale + The Time TLV structure, specified in this document, is intended to be + used as a component in a MANET routing protocol, e.g. to indicate the + expected spacing between successive transmissions of a given message + type, by including a Time TLV in transmitted messages. + + Some MANET routing protocols may employ very short spacing for some + messages and very long spacing for others, or may change the message + transmission rate according to observed behavior. For example, if a + network is observed at some point in time to exhibit a highly dynamic + topology, a very short (sub-second) message spacing could be + appropriate, whereas if the network later is observed to stabilize, + multi-hour message spacing may become appropriate. Different MANET + routing protocols and different deployments of MANET routing + protocols may have different granularity requirement and bounds on + shortest and longest spacing between successive message + transmissions. + + In addition, MANET routing protocol deployments typically use + bandwidth limited wireless network interfaces, and therefore prefer + to trade off computational complexity for a saving in the number of + bits transmitted. This is practical in this case, because the + intended usages of Time TLVs, including the specified examples of + message interval time and information validity time, do not require + high precision values of time. + + The Time TLV structure, specified in this document, caters to these + characteristics by: + + o encoding time-values, such as an interval or a duration, in an 8 + bit field; while + + o allowing these time-values to range from "very small" (e.g. 1/1024 + second) to "very long" (e.g. 45 days); and + + o allowing a MANET routing protocol, or a deployment, to parametrize + this (e.g. to attain finer granularity at the expense of a lower + upper bound) through a single parameter, C. + + The parameter C must be the same for all MANET routers in the same + deployment. + The TLV mechanism as specified in [packetbb] allows associating a "value" to either a packet, a message or to addresses. The data structure for doing so - the TLV - is identical in each of the three cases, however the TLV's position in a received packet allows determining if that TLV is a "packet TLV" (it appears in the packet header, before any messages), a "message TLV" (it appears in the TLV block immediately following a message header) or an "address block TLV" (it appears in the TLV block immediately following an address block). @@ -245,28 +292,28 @@ 6. General Time TLV Structure The following data structure allows the representation of a single time-value, or of a default time-value plus pairs of (time-values, hop counts) for when hop count dependent time-values are required. The time-values are represented as time-codes as defined in Section 5. This data structure is specified, using the regular expression syntax of [packetbb], by: - = ()* + = ()* where: is an 8 bit unsigned integer field containing a time- code as defined in Section 5. - is an 8 bit unsigned integer field specifying a hop + is an 8 bit unsigned integer field specifying a hop count from the message originator. A structure thus consists of an odd number of octets; with a repetition factor of n for the (time, hop count) pairs in the regular expression syntax, it contains 2n+1 octets. On reception, n is determined from the length. A field may be thus represented by: ... ... @@ -520,21 +567,21 @@ 11. References 11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, BCP 14, March 1997. [packetbb] Clausen, T., Dearlove, C., Dean, J., and C. Adjih, "Generalized MANET Packet/Message Format", - draft-ietf-manet-packetbb-15.txt (work in progress), + draft-ietf-manet-packetbb-16.txt (work in progress), September 2008. 11.2. Informative References [RFC3626] Clausen, T. and P. Jacquet, "The Optimized Link State Routing Protocol", RFC 3626, October 2003. Appendix A. Acknowledgements The authors would like to thank Brian Adamson and Justin Dean (both