Network Working Group Baiju V. Patel
INTERNET DRAFT Intel Corporation
Munil Shah
Microsoft Corporation
March 1997
Multicast address allocation extensions options
<draft-ietf-dhc-multopt-00.txt>
Status of this memo
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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
are:
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.
Example:
The multicast address allocation servers are listening to multicast
address 239.1.1.1. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 239.1.1.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 10.1.1.1, the option will be used as:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| code (1 byte) | 30 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 10.1.1.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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''
<draft-ietf-mboned-admin-ip-space-01.txt>
[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
Email:munils@microsoft.com
This document will expire on Sept, 1997
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