IPWAVE Working Group                                              Z. Yan
Internet-Draft                                                     CNNIC
Intended status: Standards Track                                  J. Lee
Expires: May 20, 2020                               Sangmyung University
                                                                J. Jeong
                                                 Sungkyunkwan University
                                                       November 17, 2019

 Neighbor Vehicle Discovery and Service in IP-Based Vehicular Networks


   For Cooperative Adaptive Cruise Control (C-ACC), platooning and other
   typical use cases in ITS, direct IP communication between neighbor
   vehicles poses the following two issues: 1) how to discover a
   neighbor vehicle and the demanded service; and 2) how to discover the
   link-layer address of the neighbor vehicle and selected server.  This
   document presents a solution to these problems based on DNS-SD/mDNS

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on May 20, 2020.

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Copyright Notice

   Copyright (c) 2019 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
   (https://trustee.ietf.org/license-info) in effect on the date of
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Prefix management . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Name configuration  . . . . . . . . . . . . . . . . . . . . .   3
   4.  Address configuration . . . . . . . . . . . . . . . . . . . .   4
   5.  Neighbor vehicle and service discovery  . . . . . . . . . . .   4
   6.  Mobility support  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Signaling messages  . . . . . . . . . . . . . . . . . . . . .   6
   8.  Security considerations . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   As illustrated in [DNS-Autoconf], a naming scheme is needed for the
   vehicle devices to support the unique name auto-configuration.  This
   can support the location based communicaton and scalable information
   organization in Intelligent Transportation Systems (ITS).  Based on
   the naming scheme like this and the widely-used DNS-SD/mDNS protocol,
   this document illustrates how to discover a neighbor vehicle or the
   required services with DNS resolution logic.  Before this, we make
   the following assumptions:

   o  Name: A vehicle SHOULD have a temporary name which is related to
      its geo-location.

   o  Address: A vehicle SHOULD have a global IP address which is
      routeable for the IP communications.

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   In this way, a standardized, efficient and scalable scheme can be
   used to retrieve the necessary information of the corresponding node
   (domain name, IP address, goe-location, link-local address and so on)
   for the further communications based on the DNS-SD/mDNS function.  In
   addition, the IPv6 Neighbor Discovery (ND)'s messages (e.g., RA and
   RS messages) can also be used to exchange some required information
   (e.g., mobile network prefixes and link-local address) in ITS in
   combination with DNS-SD/mDNS [MNPP].

2.  Prefix management

   The network architecture which illustrates the prefix management of
   name and address is shown in Figure 1.

       +------------+        +**********+        +------------+
       | Router1    |--------* Internet *--------| Router2    |
       |[IP-Prefix1]|        +**********+        |[IP-Prefix2]|
       +------------+                            +------------+
             |                                        |
             |                                        |
        -----------                              -----------
        |         |                              |         |
        |         |                              |         |
   +-------+    +-------+                   +-------+    +-------+
   | RSU1  |    | RSU2  |                   | RSU3  |    | RSU4  |
   |[Name1]|    |[Name2]|                   |[Name3]|    |[Name4]|
   +-------+    +-------+                   +-------+    +-------+


            Figure 1: Name and address management architecture

   As shown in Figure 1, Router1 and Router2 are two routers which can
   connect to the Internet and they hold different IP prefixes.  RSU1
   and RSU2 are two Road-Side Units (RSUs) under Router1 but hold
   different name prefixes, while RSU3 and RSU4 are two RSUs under
   Router2 but hold different name prefixes.

3.  Name configuration

   The RSU acts as an access router for the static and moving vehicles
   which want to be connected with the Internet.  Based on [RFC3646],
   [RFC6106] or extended WAVE Service Announcement (WSA) message, the
   RSU can announce its location based name prefix to the vehicles
   covered by the RSU.  This location based prefix may contain
   information such as country, city, street and so on, which will act

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   as the "domain_name" of the vehicle device name as spefified in [DNS-

4.  Address configuration

   The RSU may advertise the IP prefix to support the IPv6 Stateless
   Address Autoconfiguration (SLAAC) operation of vehicle devices and
   movement detection (in the IP layer).  If the DHCP is used for the
   address configuration, RSU also acts as functional entity such as a
   DHCP proxy and DHCP server.

5.  Neighbor vehicle and service discovery

   (1) RSU based

   Vehicles may have direct connection with the serving RSU and join the
   same link with the serving RSU.  Then the RSU can maintain the
   registered vehicle or service in its serving domain.  Otherwise, the
   RSU acts as a relay node for discovering in a proxy manner.

   When a vehicle wants to locate the potential nearby neighbor and
   further establish the communication, the vehicle will trigger the
   direct unicast query to port 5353 or legacy unicast DNS query to the
   RSU.  RSU may respond directly if it has the related information,
   otherwise, the RSU multicasts the DNS query to the multicast group to
   retrieve the related information.  A unicast response is the first
   recommendation here because it can suppress the flooding, but of
   course, the DNS response message can also be multicasted as an active
   announcement of the verhicle or service existence.

   (2) Ad-hoc based

   Vehicles may communicate with each other or sense the front and rear
   neighbor vehicles with DSRC, WiFi, Bluetooth or other short-distance
   communication technologies, connecting each other in the Ad-hoc
   manner.  Then the discovery can be executed in an infrastructure-less
   manner with the following phases, as specified in mDNS.

   o  Probing: When a vehicle starts up, wakes up from sleeping mode or
      the Vehicular Ad Hoc Networks (VANET) topology changes (after
      configuration of the name and address), it should probe the
      availability of the service with which it can provide other
      vehicles.  Then the vehicle periodically announces the service and
      its existence with unsolicited multicast DNS response containing,
      in the Answer Section, all of its service name, DNS name, IP
      address and other information.  The vehicle also updates the
      related information actively if there is any change.

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   o  Discovering: To support the service and neighbor vehicle discovery
      in the dynamic and fragmentation-possible environment in VANET,
      different query modes of mDNS can be used for different scenarios:
      1) One-Short Multicast DNS Query can be used to locate a specific
      vehicle. 2) Continuous Multicast DNS Query can be used to locate
      the nearby vehicles which are moving.

   o  Refreshing: After the neighbor discovery as illustrated above, the
      vehicles should continually exchange their DNS name, IP address,
      geo-location and other information in order to refresh the
      established communications.  For example, the Multiple Questions
      Multicast Responses can be used to update the caches of receivers
      efficiently and Multiple Questions Unicast Responses can be used
      to support the fast bootstrapping when a new vehicle joins.

   o  Goodbye: When the vehicle arrives at its destination, stops
      temporarily or shuts down its communication or sensing devices, it
      will announce the service suspending and its inexistence with an
      unsolicited multicast DNS response packet, giving the same
      Resource Records (RRs) (containing its DNS name and IP address),
      but with zero Time-To-Live (TTL).

6.  Mobility support

   During the movement of the vehicle, it may cross different RSUs.
   When a vehicle enters the communication coverage of a new RSU, the
   new domain prefix and new IP prefix may be learned.  Generally, there
   are two main cases for the mobility:

   o  The domain name changes and the IP prefix remains, as shown in
      Figure 1, the vehicle moves from the coverage of RSU1 to the
      coverage of RSU2.  The vehicle will configure a new DNS name from
      RSU2 and may update the new DNS name in the local database (e.g.,
      RSU).  But the vehicle should keep its previous DNS name for a
      while until that all the communicating neighbors have learned its
      new DNS name.  During this duration, the vehicle will contain both
      the previous and new DNS names in the DNS response message.

   o  Both the domain name and IP prefix change, as shown in Figure 1,
      the vehicle performs a handover from RSU2 to RSU3.  The vehicle
      will configure both its new DNS name and new IP address from RSU3
      and update them in the local database.  Then the above scheme can
      also be used or with IP-layer mobility management protocols (e.g.,
      Mobile IPv6 [RFC6275] and Proxy Mobile IPv6 [RFC5213]).

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7.  Signaling messages

   To facilitate the further communication, the link-layer address and
   geo-information may be included in the DNS message in a piggyback
   manner.  Otherwise, this information may be obtained through the
   following IPv6 Neighbor Discovery Protocol (NDP) or other procedures
   (e.g., DHCP and WSA).

8.  Security considerations

   In order to reduce the DNS traffic on the wireless link and avoid the
   unnecessary flooding, the related schemes in mDNS can be used, such
   as: Known-Answer Suppression, Multipacket Known-Answer Suppression,
   Duplicate Question Suppression and Duplicate Answer Suppression.

   In order to guarantee the origination of the DNS message and avoid
   the DNS message tampering, the security consideration in mDNS should
   also be adopted.

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC3646]  Droms, R., Ed., "DNS Configuration options for Dynamic
              Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
              DOI 10.17487/RFC3646, December 2003,

   [RFC5213]  Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
              Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
              RFC 5213, DOI 10.17487/RFC5213, August 2008,

   [RFC6106]  Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
              "IPv6 Router Advertisement Options for DNS Configuration",
              RFC 6106, DOI 10.17487/RFC6106, November 2010,

   [RFC6275]  Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
              Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July
              2011, <https://www.rfc-editor.org/info/rfc6275>.

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   [RFC6762]  Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
              DOI 10.17487/RFC6762, February 2013,

   [RFC6763]  Cheshire, S. and M. Krochmal, "DNS-Based Service
              Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,

9.2.  Informative References

              Jeong, J., Lee, S., and J. Park, "DNS Name
              Autoconfiguration for Internet-of-Things Devices in IP-
              Based Vehicular Networks",  draft-jeong-ipwave-iot-dns-
              autoconf-07, November 2019.

   [MNPP]     Lee, J., Tsukada, M., and T. Ernst, "Mobile Network Prefix
              Provisioning",  draft-jhlee-mext-mnpp-00, October 2009.

Authors' Addresses

   Zhiwei Yan
   No.4 South 4th Street, Zhongguancun
   Beijing  100190

   EMail: yan@cnnic.cn

   Jong-Hyouk Lee
   Sangmyung University
   31, Sangmyeongdae-gil, Dongnam-gu
   Republic of Korea

   EMail: jonghyouk@smu.ac.kr

   Jaehoon Paul Jeong
   Department of Computer Science and Engineering
   Sungkyunkwan University
   2066 Seobu-Ro, Jangan-Gu
   Suwon, Gyeonggi-Do
   Republic of Korea

   EMail: pauljeong@skku.edu

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