MANET Working Group Sanghyun Ahn Internet Draft University of Seoul Expires: April 19, 2015 October 27, 2014 DSR Usage for the VANET Routing draft-ahn-manet-dsr-vanet-00.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to format it for publication as an RFC or to translate it into languages other than English. 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 will expire on April 19, 2015. Copyright Notice Copyright (c) 2014 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. Ahn Expires April 19, 2015 [Page 1] Internet-Draft DSR Usage for the VANET Routing October 2014 Abstract This document describes how DSR [1] can be applied in the vehicular ad hoc network (VANET) environment. Since DSR uses the source routing mechanism, it can be appropriate for the VANET routing mechanisms operating based on the source routing. Therefore, in this draft, we describe how we can adapt DSR to the VANET environment. Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. DSR for the VANET Routing . . . . . . . . . . . . . . . . . . 3 4. Modification on DSR . . . . . . . . . . . . . . . . . . . . . 4 5. Other Considerations . . . . . . . . . . . . . . . . . . . . . 4 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 4 Ahn Expires April 19, 2015 [Page 2] Internet-Draft DSR Usage for the VANET Routing October 2014 1. Requirements notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. Introduction The vehicular ad hoc network (VANET) is a special form of the MANET in which vehicles (mobile nodes) move along the given road layout [2]. When a route from a source node to a destination node is discovered, the obtained route has to be represented with a sequence of roads instead of nodes (vehicles) since vehicles move too fast. If a route is represented with nodes, the route can be easily broken, which incurs too frequent route maintenance procedure. In this case, the source routing is appropriate. That is, once the route information is obtained, data are sent along the roads in the route information and, in the header of each data packet, the route information is included. Since DSR [1] uses the source routing mechanism, in this draft, we describe the issues on applying DSR to the VANET environment. 3. DSR for the VANET Routing In DSR, the route discovery is initiated by the source node's broadcasting of an RREQ message. Each intermediate node forwards the received RREQ message via broadcast and the route information is recorded in the RREQ message. Once the destination node receives an RREQ message, it sends out an RREP message with the collected route information back to the source. Or, if an intermediate node has the route information to the destination, it stops forwarding the RREQ message and sends an RREP message back to the source. In a VANET, a 'node' is a fast moving vehicle and, as a result, the network topology changes drastically. Thus, rather than recording the passing-by nodes in the RREQ message, it is better to record the passing-by roads in the RREQ message. This may reduce the possibility of route maintenance. In this case, since 'road' is the unit element of the route information and there is no representative entity to keep the route state of a road, the RREP message has to be generated by only the destination node. Ahn Expires April 19, 2015 [Page 3] Internet-Draft DSR Usage for the VANET Routing October 2014 There can be more than one node on a road, so RREQ messages with the same route record can be generated by multiple nodes. Therefore, a mechanism to reduce the number of RREQ messages with the same route record information is required. Also, since a sequence of 'road's represents a route, the automatic route shortening, the gratuitous RREP message and the optional flow state extension capabilities of DSR may not be necessary. Hence, a simplified version of DSR is adequate for the VANET routing. 4. Modifications on DSR TBD. 5. Other Considerations TBD. References [1] D. Johnson, Y. Hu and D. Maltz, "The Dynamic Source Routing Protocol," RFC 4728, February 2007. [2] W. Chen, R. Guha., T. Kwon, J. Lee, and I. Hsu, "A Survey and Challenges in Routing and Data Dissemination in Vehicular Ad Hoc Networks", Wiley Wireless Communications and Mobile Computing, vol. 11, no. 7, pp. 787-795, 2011. Author's Address Sanghyun Ahn University of Seoul 90, Cheonnong-dong, Tongdaemun-gu Seoul 130-743 Korea Email: ahn@uos.ac.kr Ahn Expires April 19, 2015 [Page 4]