【文章內(nèi)容簡介】 pplicability Statement The AODV routing protocol is designed for mobile ad hoc networks with populations of tens to thousands of mobile nodes. AODV can handle low, moderate, and relatively high mobility rates, as well as a variety of data traffic levels. AODV is designed for use in networks where the nodes can all trust each other, either by use of preconfigured keys or because it is known that there are no malicious nodes. AODV has been designed to reduce the dissemination of control traffic and eliminate overhead on data traffic in order to improve scalability and performance. A recent study [4] has indicated that, for networks of limited size, reliable munications can be managed by nodes that implement only a very limited number of AODV features. For instance, in networks of 50 nodes, the performance does not suffer very much even if nodes only implement RREQ and RREP, without any RREPs from intermediate nodes. Thus, we have revised the original AODV specification so that many features are no longer mandated, even if they are strongly remended for all general purpose ad hoc network nodes. Networks of nodes which only implement the mandated specification may not be useful except for certain limited scenarios, and may even effectively consume more power than when the nodes contain the congestion control and latency reduction features remended in section 7.5. Message Formats In this section, the formats for the basic AODV messages are specified. RREQ and RREP messages MUST be implemented by all AODV nodes. RERR and RREPACK messages SHOULD be implemented, but there may be cases where nodes can be built for certain limited deployments that do not need to have the features enabled by those messages.Perkins, BeldingRoyer, Chakeres Expires 19 April 2003 [Page 4]Internet Draft AODV 19 October 2003. Route Request (RREQ) Message Format 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 |D|G| Reserved | Hop Count | +++++++++++++++++++++++++++++++++ | RREQ ID | +++++++++++++++++++++++++++++++++ | Destination IP Address | +++++++++++++++++++++++++++++++++ | Destination Sequence Number | +++++++++++++++++++++++++++++++++ | Originator IP Address | +++++++++++++++++++++++++++++++++ | Originator Sequence Number | +++++++++++++++++++++++++++++++++ | Next Path Node IP Address | +++++++++++++++++++++++++++++++++ | Next Path Node Sequence Number | +++++++++++++++++++++++++++++++++ | (additional node IP address and sequence number pairs) ... +++++++++++++++++++++++++++++++++ The format of the Route Request message is illustrated above, and contains the following fields: Type 1 D Destinationonly flag. If set a intermediate node may not respond to this RREQ (see section ). G Gratuitous Route Reply flag. Indicates whether a gratuitous RREP should be sent to the destination (see section ). This flag should be set for traffic bidirectional traffic, such as TCP. Reserved Sent as 0。 ignored on reception. Hop Count The number of hops from the originating node to the node handling the request. This field also indicates the number of accumulated path node IP addresses and sequence numbers in the RREQ. RREQ ID A sequence number uniquely identifying the particular RREQ when taken in conjunction with the originating node39。s IP address.Perkins, BeldingRoyer, Chakeres Expires 19 April 2003 [Page 5]Internet Draft AODV 19 October 2003 Destination IP Address The IP address of the destination for which a route is desired. Destination Sequence Number The latest sequence number received by the originator for any route towards the destination. Originator IP Address The IP address of the originating node that issued the Route Request. Originator Sequence Number The current sequence number of the originating node. Next Path Node IP Address The IP address of the next node along the path from the Originator to the Destination. Next Path Node Sequence Number The Sequence Number of the next node along the path from the Originator to the Destination.. Route Reply (RREP) Message Format 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 |A|Reserved |