dsr_draft1.txt

dsr路协议规范

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Versions: 00 01 02 03 05 06 07 08 09 10 RFC 4728                        
                                                                        

IETF MANET Working Group               David B. Johnson, Rice University
INTERNET-DRAFT                              David A. Maltz, AON Networks
2 March 2001                                Yih-Chun Hu, Rice University
                         Jorjeta G. Jetcheva, Carnegie Mellon University



     The Dynamic Source Routing Protocol for Mobile Ad Hoc Networks

                     <draft-ietf-manet-dsr-05.txt>


Status of This Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC 2026 except that the right to
   produce derivative works is not granted.

   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 is a submission to the IETF Mobile Ad Hoc
   Networks (MANET) Working Group.  Comments on this draft may be sent
   to the Working Group at [e-mail], or may be sent
   directly to the authors.


















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Abstract

   The Dynamic Source Routing protocol (DSR) is a simple and efficient
   routing protocol designed specifically for use in multi-hop wireless
   ad hoc networks of mobile nodes.  DSR allows the network to be
   completely self-organizing and self-configuring, without the need
   for any existing network infrastructure or administration.  The
   protocol is composed of the two mechanisms of "Route Discovery"
   and "Route Maintenance", which work together to allow nodes to
   discover and maintain source routes to arbitrary destinations in the
   ad hoc network.  The use of source routing allows packet routing
   to be trivially loop-free, avoids the need for up-to-date routing
   information in the intermediate nodes through which packets are
   forwarded, and allows nodes forwarding or overhearing packets to
   cache the routing information in them for their own future use.  All
   aspects of the protocol operate entirely on-demand, allowing the
   routing packet overhead of DSR to scale automatically to only that
   needed to react to changes in the routes currently in use.  This
   document specifies the operation of the DSR protocol for routing
   unicast IP packets in multi-hop wireless ad hoc networks.































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                                Contents



Status of This Memo                                                    i

Abstract                                                              ii

 1. Introduction                                                       1

 2. Assumptions                                                        3

 3. DSR Protocol Overview                                              5
     3.1. Basic DSR Route Discovery . . . . . . . . . . . . . . . .    5
     3.2. Basic DSR Route Maintenance . . . . . . . . . . . . . . .    7
     3.3. Additional Route Discovery Features . . . . . . . . . . .    8
           3.3.1. Caching Overheard Routing Information . . . . . .    8
           3.3.2. Replying to Route Requests using Cached Routes  .    9
           3.3.3. Preventing Route Reply Storms . . . . . . . . . .   10
           3.3.4. Route Request Hop Limits  . . . . . . . . . . . .   12
     3.4. Additional Route Maintenance Features . . . . . . . . . .   13
           3.4.1. Packet Salvaging  . . . . . . . . . . . . . . . .   13
           3.4.2. Automatic Route Shortening  . . . . . . . . . . .   13
           3.4.3. Increased Spreading of Route Error Messages . . .   14

 4. Conceptual Data Structures                                        15
     4.1. Route Cache . . . . . . . . . . . . . . . . . . . . . . .   15
     4.2. Route Request Table . . . . . . . . . . . . . . . . . . .   17
     4.3. Send Buffer . . . . . . . . . . . . . . . . . . . . . . .   18
     4.4. Retransmission Buffer . . . . . . . . . . . . . . . . . .   19

 5. DSR Header Format                                                 20
     5.1. Fixed Portion of DSR Header . . . . . . . . . . . . . . .   21
     5.2. Route Request Option  . . . . . . . . . . . . . . . . . .   23
     5.3. Route Reply Option  . . . . . . . . . . . . . . . . . . .   25
     5.4. Route Error Option  . . . . . . . . . . . . . . . . . . .   27
     5.5. Acknowledgment Request Option . . . . . . . . . . . . . .   29
     5.6. Acknowledgment Option . . . . . . . . . . . . . . . . . .   30
     5.7. Source Route Option . . . . . . . . . . . . . . . . . . .   31
     5.8. Pad1 Option . . . . . . . . . . . . . . . . . . . . . . .   33
     5.9. PadN Option . . . . . . . . . . . . . . . . . . . . . . .   34

 6. Detailed Operation                                                35
     6.1. General Packet Processing . . . . . . . . . . . . . . . .   35
           6.1.1. Originating a Packet  . . . . . . . . . . . . . .   35
           6.1.2. Adding a DSR Header to a Packet . . . . . . . . .   35
           6.1.3. Adding a Source Route Option to a Packet  . . . .   36
           6.1.4. Receiving a Packet  . . . . . . . . . . . . . . .   36



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           6.1.5. Processing a Received Source Route Option . . . .   38
     6.2. Route Discovery Processing  . . . . . . . . . . . . . . .   40
           6.2.1. Originating a Route Request . . . . . . . . . . .   40
           6.2.2. Processing a Received Route Request Option  . . .   42
           6.2.3. Generating Route Replies using the Route Cache  .   43
           6.2.4. Originating a Route Reply . . . . . . . . . . . .   44
           6.2.5. Processing a Route Reply Option . . . . . . . . .   46
     6.3. Route Maintenance Processing  . . . . . . . . . . . . . .   47
           6.3.1. Using Network-Layer Acknowledgments . . . . . . .   47
           6.3.2. Using Link Layer Acknowledgments  . . . . . . . .   48
           6.3.3. Originating a Route Error . . . . . . . . . . . .   48
           6.3.4. Processing a Route Error Option . . . . . . . . .   49
           6.3.5. Salvaging a Packet  . . . . . . . . . . . . . . .   49

 7. Constants                                                         50

 8. IANA Considerations                                               51

 9. Security Considerations                                           52

Appendix A. Location of DSR in the ISO Network Reference Model        53

Appendix B. Implementation and Evaluation Status                      54

Acknowledgements                                                      55

References                                                            56

Chair's Address                                                       59

Authors' Addresses                                                    60






















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1. Introduction

   The Dynamic Source Routing protocol (DSR) [12, 13] is a simple and
   efficient routing protocol designed specifically for use in multi-hop
   wireless ad hoc networks of mobile nodes.  Using DSR, the network
   is completely self-organizing and self-configuring, requiring no
   existing network infrastructure or administration.  Network nodes
   cooperate to forward packets for each other to allow communication
   over multiple "hops" between nodes not directly within wireless
   transmission range of one another.  As nodes in the network move
   about or join or leave the network, and as wireless transmission
   conditions such as sources of interference change, all routing is
   automatically determined and maintained by the DSR routing protocol.
   Since the number or sequence of intermediate hops needed to reach any
   destination may change at any time, the resulting network topology
   may be quite rich and rapidly changing.

   The DSR protocol allows nodes to dynamically discover a source
   route across multiple network hops to any destination in the ad hoc
   network.  Each data packet sent then carries in its header the
   complete, ordered list of nodes through which the packet will pass,
   allowing packet routing to be trivially loop-free and avoiding the
   need for up-to-date routing information in the intermediate nodes
   through which the packet is forwarded.  By including this source
   route in the header of each data packet, other nodes forwarding or
   overhearing any of these packets may also easily cache this routing
   information for future use.

   In designing DSR, we sought to create a routing protocol that had
   very low overhead yet was able to react quickly to changes in the
   network.  The DSR protocol provides highly reactive service to help
   ensure successful delivery of data packets in spite of node movement
   or other changes in network conditions.

   The DSR protocol is composed of two mechanisms that work together to
   allow the discovery and maintenance of source routes in the ad hoc
   network:

    -  Route Discovery is the mechanism by which a node S wishing to
       send a packet to a destination node D obtains a source route
       to D.  Route Discovery is used only when S attempts to send a
       packet to D and does not already know a route to D.

    -  Route Maintenance is the mechanism by which node S is able
       to detect, while using a source route to D, if the network
       topology has changed such that it can no longer use its route
       to D because a link along the route no longer works.  When Route
       Maintenance indicates a source route is broken, S can attempt to
       use any other route it happens to know to D, or can invoke Route
       Discovery again to find a new route for subsequent packets to D.



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       Route Maintenance for this route is used only when S is actually
       sending packets to D.

   In DSR, Route Discovery and Route Maintenance each operate entirely
   "on demand".  In particular, unlike other protocols, DSR requires no
   periodic packets of any kind at any level within the network.  For
   example, DSR does not use any periodic routing advertisement, link
   status sensing, or neighbor detection packets, and does not rely on