Discovering Location-to-Service Translation (LoST) Servers Using the Dynamic Host Configuration Protocol (DHCP)
RFC 5223

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Network Working Group                                     H. Schulzrinne
Request for Comments: 5223                           Columbia University
Category: Standards Track                                        J. Polk
                                                                   Cisco
                                                           H. Tschofenig
                                                  Nokia Siemens Networks
                                                             August 2008

  Discovering Location-to-Service Translation (LoST) Servers Using the
               Dynamic Host Configuration Protocol (DHCP)

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   The Location-to-Service Translation (LoST) Protocol describes an XML-
   based protocol for mapping service identifiers and geospatial or
   civic location information to service contact Uniform Resource
   Locators (URLs).  LoST servers can be located anywhere, but a
   placement closer to the end host, e.g., in the access network, is
   desirable.  In disaster situations with intermittent network
   connectivity, such a LoST server placement provides benefits
   regarding the resiliency of emergency service communication.

   This document describes how a LoST client can discover a LoST server
   using the Dynamic Host Configuration Protocol (DHCP).

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 2
   3.  Domain Name Encoding  . . . . . . . . . . . . . . . . . . . . . 3
   4.  LoST Server DHCPv4 Option . . . . . . . . . . . . . . . . . . . 3
   5.  LoST Server DHCPv6 Option . . . . . . . . . . . . . . . . . . . 4
   6.  Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
     7.1.  DHCPv4 Option . . . . . . . . . . . . . . . . . . . . . . . 5
     7.2.  DHCPv6 Option . . . . . . . . . . . . . . . . . . . . . . . 5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     10.1. Normative References  . . . . . . . . . . . . . . . . . . . 6
     10.2. Informative References  . . . . . . . . . . . . . . . . . . 6

1.  Introduction

   The Location-to-Service Translation (LoST) Protocol [RFC5222]
   describes an XML-based protocol for mapping service identifiers and
   geospatial or civic location information to service contact Uniform
   Resource Locators (URLs).

   In order to interact with a LoST server, the LoST client needs to
   discover the server's IP address.  Several mechanisms can be used to
   learn this address, including manual configuration.  In environments
   where the access network itself either deploys a LoST server or knows
   a third party that operates a LoST server, DHCP can provide the end
   host with a domain name.  This domain name is then used as input to
   the DNS-based resolution mechanism described in LoST [RFC5222] that
   reuses the URI-enabled NAPTR specification (see [RFC4848]).

   This document specifies a DHCPv4 and a DHCPv6 option that allows LoST
   clients to discover local LoST servers.

   Section 2 provides terminology.  Section 3 shows the encoding of the
   domain name.  Section 4 describes the DHCPv4 option while Section 5
   describes the DHCPv6 option, with the same functionality.  IANA and
   Security Considerations complete the document in Sections 7 and 8.

2.  Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in RFC 2119
   [RFC2119].

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   Within this document, we use terminology from [RFC5012] and
   [RFC5222].

3.  Domain Name Encoding

   This section describes the encoding of the domain name used in the
   DHCPv4 option shown in Section 4 and also used in the DHCPv6 option
   shown in Section 5.

   The domain name is encoded according to Section 3.1 of RFC 1035
   [RFC1035] whereby each label is represented as a one-octet length
   field followed by that number of octets.  Since every domain name
   ends with the null label of the root, a domain name is terminated by