Intermediate RREP for dynamic MANET On-demand (AODVv2) Routing
draft-perkins-irrep-01

Abstract

The Dynamic MANET On-demand (AODVv2) routing protocol is intended for use by mobile routers in wireless, multihop networks. AODVv2 determines unicast routes among AODVv2 routers within the network in an on-demand fashion, offering on-demand convergence in dynamic topologies. This document specifies an extension to AODVv2 (and possibly other reactive routing protocols) enabling intermediate nodes to shorten route discovery times.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on April 24, 2013.

Copyright Notice

Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

• 1. Overview
• 2. Terminology
• 3. Intermediate AODVv2 Router RREP Creation
• 4. Acknowledgments
• 5. Security Considerations
• 6. References
• 6.1. Normative References
• 6.2. Informative References
• Authors' Addresses

1. Overview

The Dynamic MANET On-demand (AODVv2) routing protocol enables on-demand, multihop unicast routing among participating AODVv2 routers. The basic operations of the AODVv2 protocol are route discovery and route maintenance. Route discovery is performed by an AODVv2 router when one of its clients transmits a packet towards a destination for which the router does not have a route. Route maintenance is performed to help ensure that the route being used to forward packets from the source to the destination remains operational.

During route discovery, the originator's AODVv2 router initiates flooding of a Route Request (RREQ) throughout the network to find a route to a particular destination, via the AODVv2 router responsible for this destination. During this hop-by-hop flooding process, each intermediate AODVv2 router records a route to the originator. If the intermediate router has a route to the destination requested in the RREQ, it may by following the specification in this document supply that routing information to the originator of the RREQ. Such an RREP message is termed an "Intermediate RREP" (iRREP). The Intermediate router also forwards another RREP message to the requested destination, supplying the destination and other intermediate routers with a route towards the originator of the RREQ. When the originator's AODVv2 router receives the iRREP, and the destination receives iRREP for the originator, routes have then been established between the originating AODVv2 router and the target AODVv2 router in both directions.

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Additionally, this document uses some terminology from [RFC5444] and [I-D.ietf-manet-dymo], duplicated here for convenience.

AODVv2 Sequence Number (SeqNum)

An AODVv2 Sequence Number is maintained by each AODVv2 router process. This sequence number is used by other AODVv2 routers to identify the temporal order of routing information generated and ensure loop-free routes.

Router Client

An AODVv2 router may be configured with a list of other IP addresses and networks which correspond to other non-router nodes which require the services of the AODVv2 router for route discovery and maintenance. An AODVv2 is always its own client, so that the list of client IP addresses is never empty. corresponds to the AODVv2 router process currently performing a calculation or processing a message.

Originating Node (OrigNode)

The originating node is the source, its AODVv2 router creates a AODVv2 control message on its behalf in an effort to flood some routing information. The originating node is also referred to as a particular message's originator.

Route Reply (RREP)

A RREP message is used to flood routing information about the RREP TargetNode to the RREP OrigNode and the AODVv2 routers between them.

Route Request (RREQ)

A RREQ message is used to discover a valid route to a particular destination address, called the RREQ TargetNode. When an AODVv2 router processes a RREQ, it learns routing information on how to reach the RREQ OrigNode.

Target Node (TargetNode)

The TargetNode is the ultimate destination of a data packet.

This Node (ThisNode)

ThisNode corresponds to the AODVv2 router process currently performing a calculation or processing a message.

3. Intermediate AODVv2 Router RREP Creation

Sometimes an AODVv2 router other than the TargetNode's AODVv2 router (call it an "intermediate AODVv2 router") has routing information that can satisfy an incoming RREQ. An intermediate AODVv2 router can issue a intermediate AODVv2 router RREP on behalf of the TargetNode's AODVv2 router.

If ThisNode is not the TargetNode, and the RREQ contains the TargetNode.AddTLV.SeqNum, and ThisNode has a forwarding route to the TargetNode with a SeqNum satisfying Route.TargetNode.SeqNum > RREQ.TargetNode.AddTLV.SeqNum (using signed 16-bit arithmetic); then ThisNode MAY respond with an intermediate AODVv2 router RREP (iRREP). When an intermediate AODVv2 router creates a iRREP in response to a RREQ on behalf of the TargetNode's AODVv2 router, it transmits the iRREP to the RREQ OrigNode with additional routing information (Address, Prefix, SeqNum, Dist, etc.) about the RREQ TargetNode. After an AODVv2 router sends iRREP, it need not perform any more operations for the RREQ being processed.

The Intermediate AODVv2 router SHOULD also issue a RREP to the RREQ TargetNode, so that the RREQ TargetNode receives routing information on how to reach the RREQ OrigNode.

4. Acknowledgments

TBD

5. Security Considerations

If AODVv2 RREP messages are not secured, then the threats are the same. Otherwise, the ability of intermediate nodes to issue RREP on behalf of a destination node changes the security vulnerability of an ad hoc network. In that case, then the originator and TargetNode of the RREQ may need to maintain security associations with additional nodes in the ad hoc network in order to verify iRREP. Doing this depends on the exact nature of the method by which the control messages are made secure, and is beyond the scope of this document.

6. References

6.1. Normative References

6.2. Informative References

Authors' Addresses