MANET Working Group Sanghyun Ahn Internet Draft University of Seoul Expires: May 23, 2018 November 30, 2017 DSR Usage for the VANET Routing draft-ahn-manet-dsr-vanet-01.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 May 23, 2018. Copyright Notice Copyright (c) 2017 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 May 23, 2018 [Page 1] Internet-Draft DSR Usage for the VANET Routing November 2017 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 modify DSR for the VANET source routing. Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. DSR for the VANET Routing . . . . . . . . . . . . . . . . . . 3 4. Redefinition of DSR Options Header . . . . . . . . . . . . . . 4 4.1 Redefined DSR Route Request Option . . . . . . . . . . . . . . 4 4.2 Redefined DSR Route Reply Option . . . . . . . . . . . . . . . 5 5. Other Considerations . . . . . . . . . . . . . . . . . . . . . 5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Ahn Expires May 23, 2018 [Page 2] Internet-Draft DSR Usage for the VANET Routing November 2017 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 as a sequence of nodes, the route can be easily broken, which incurs too frequent route maintenance procedure. This problem can be resolved by representing a route as a sequence of roads. 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. The route discovery capability of DSR [1] is desirable to fiure out a route composed of roads with a proper number of vehicles. Therefore, in this draft, we define how DSR messages can be used for VANET. 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 May 23, 2018 [Page 3] Internet-Draft DSR Usage for the VANET Routing November 2017 There can be more than one node on a road, so RREQ messages with the same route information can be generated by multiple nodes. Therefore, the destination has to ignore RREQ messages with the same route information as that of the already chosen RREQ message. 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. Redefined DSR Options Header 4.1 Redefined DSR Route Request Option The Route Request option in the DSR Options header is redefined as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option Type | Opt Data Len | Identification | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Target Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Road ID[1] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Road ID[2] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Road ID[n] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IP fields The same as described in [1]. Route Request fields The same as described in [1] except for the Road ID fields. Road ID[i] The identifier of the ith road which this RREQ message has passed by on the route from the source vehicle. Ahn Expires May 23, 2018 [Page 4] Internet-Draft DSR Usage for the VANET Routing November 2017 4.2 Redefined DSR Route Reply Option The Route Reply option in the DSR Options header is redefined as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option Type | Opt Data Len |L| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Road ID[1] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Road ID[2] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Road ID[n] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IP fields The same as described in [1]. Route Reply fields The same as described in [1] except for the Road ID fields. Road ID[i] field The identifier of the ith road from the source vehicle to the destination vehicle. 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, 2011. Ahn Expires May 23, 2018 [Page 5] Internet-Draft DSR Usage for the VANET Routing November 2017 Author's Address Sanghyun Ahn University of Seoul 90, Cheonnong-dong, Tongdaemun-gu Seoul 130-743 Korea Email: ahn@uos.ac.kr Ahn Expires May 23, 2018 [Page 6]