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Versions: 00 01 02 03                                                   
Network Working Group                                     Baiju V. Patel
INTERNET DRAFT                                         Intel Corporation

                                                              Munil Shah
                                                   Microsoft Corporation

                                                              March 1997

                  Multicast address allocation extensions options

Status of this memo

   This document is an Internet-Draft. 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
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   ftp.isi.edu (US West Coast).

1. Abstract

   This document describes host configuration options that may be used
   by multicast address allocation protocols[3]. The options include
   critical information such as the IP address (unicast or multicast)
   of the multicast address allocation server(s) and a list of
   multicast scopes supported by respective servers. These options are
   designed to work with the extensions to DHCP [1] servers to support
   multicast address allocation (described in a separate draft),
   however, their use may not be limited to the above protocol.

2 Requirements

   Throughout this document, the words that are used to define the
   significance of particular requirements are capitalized.  These words

      o "MUST"

        This word or the adjective "REQUIRED" means that the
        item is an absolute requirement of this specification.

Patel & Shah                                                    [Page 1]

      o "MUST NOT"

        This phrase means that the item is an absolute prohibition
        of this specification.

      o "SHOULD"

        This word or the adjective "RECOMMENDED" means that there
        may exist valid reasons in particular circumstances to ignore
        this item, but the full implications should be understood and
        the case carefully weighed before choosing a different course.

      o "SHOULD NOT"

        This phrase means that there may exist valid reasons in
        particular circumstances when the listed behavior is acceptable
        or even useful, but the full implications should be understood
        and the case carefully weighed before implementing any behavior
        described with this label.

      o "MAY"

        This word or the adjective "OPTIONAL" means that this item is
        truly optional.  One vendor may choose to include the item
        because a particular marketplace requires it or because it
        enhances the product, for example; another vendor may omit the
        same item.

3 Terminology

   This document uses the following terms:

      o "DHCP client"

        A DHCP client is an Internet host using DHCP to obtain
        configuration parameters such as a network address.

      o "DHCP server"

        A DHCP server is an Internet host that returns configuration
        parameters to DHCP clients.

      o "BOOTP relay agent"

        A BOOTP relay agent or relay agent is an Internet host or router
        that passes DHCP messages between DHCP clients and DHCP servers.
        DHCP is designed to use the same relay agent behavior as
        specified in the BOOTP protocol specification.

      o "binding"

        A binding is a collection of configuration parameters, including
        at least an IP address, associated with or "bound to" a DHCP
        client.  Bindings are managed by DHCP servers.

Patel & Shah                                                    [Page 2]

4 Multicast Scope List Option

   Any client attempting to request a multicast address must know the
   address to which the server is listening to (this address may be
   unicast or multicast address), and a list of multicast scopes
   supported by the multicast address servers.  This option is
   specifically designed to provide the multicast address server
   address and the scope list that can specifically be used by the
   protocol described in [3], however, its use is not limited to the
   protocol described in [3].

   The format of the multicast scope list option is:

                | code (1 byte) | length (1byte)|
                | IP address (4 bytes)          |
                | TTL (1 byte)  | N             |
                | Scope list

   Where IP address is the address of the MDHCP server, to its best
   knowledge, reachable from the client via unicast or multicast.
   packets. The IP address may be a unicast or multicast address and
   the multicast address server must process the packets addressed to
   this address. The TTL value is the maximum time to leave value to
   be used for the packets sent to the IP address specified in this
   option. The scope list a list of N tuples, where each tuple is of
   the form,

       | scope ID(4 byte) | Scope len (1 bute) | Scope description |

   where scope ID is a unique identifier to designate the scope, scope
   description is a string describing the scope (need not be null
   terminated) and scope len is the length of scope description.

   Scope id is numeric representation of the scope and is used by the
   client to indicate a multicast scope to the server. In order to
   keep the usage of scope id consistent in the MBONE, this draft
   SHOULD be coordinated with [3] reserve a scope id for each
   multicast range in [3]. The scope id with its MSB(most significant
   bit) of 1 should be used for administratively scoped multicast
   address range. And the scope id with its MSB of 0 should be used to
   represent other pre-defined internet scopes.


   The multicast address allocation servers are listening to multicast
   address The maximum allowed value for the TTL for this
   address is 16. There are two scopes supported by the multicast

Patel & Shah                                                    [Page 3]

   address allocation server: 1) Inside the abcd.com, 2) world. Then
   this option will be used as:

                | code (1 byte) | 30            |
                |                     |
                | 16            | 2             |
                | 0 |16| Inside abcd.com        |
                | 1 |5 |world                   |

   Instead of specifying a multicast address, the option may also
   specify a unicast address of the multicast address server. In above
   example, if the address of the multicast address server (see [3])
   was, the option will be used as:

                | code (1 byte) | 30            |
                |                      |
                | 16            | 2             |
                | 0 |16|"Inside abcd.com"       |
                | 1 |5|"world"                  |

4  References

   [1] Droms, R., "Dynamic Host Configuration Protocol", RFC1541,
   October 1993

   [2] Alexander, S., and R. Droms, "DHCP Options and BOOTP Vendor
       Extensions", RFC 1533, Lachman Technology, Inc., Bucknell
       University, October 1993.

   [3] Meyer, D., ``Administratively scoped IP Multicast''

   [4] Patel, B., and Shah, M., ``Multicast address allocation
       extensions to the Dynamic Host Configuration
       Protocol''  <draft-ietf-dhc-mdhcp-00.txt>

Patel & Shah                                                    [Page 4]

5  Author's Address

   Baiju V. Patel
   Intel Corp.
   2111 NE 25th Ave.
   Hillsboro, OR 97124

   Phone: 503 264 2422
   EMail: baiju@ibeam.intel.com

   Munil Shah
   Microsoft Corporation
   One Microsoft Way
   Redmond, WA 98052

   Phone:206 703 3924

   This document will expire on Sept, 1997

Patel & Shah                                                    [Page 5]