Clarifications and Extensions for the Bootstrap Protocol
RFC 1532
| Document | Type |
RFC - Proposed Standard
(October 1993; No errata)
Obsoleted by RFC 1542
Updates RFC 951
Was draft-ietf-dhc-bootp (dhc WG)
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|---|---|---|---|
| Last updated | 2013-03-02 | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 1532 (Proposed Standard) | |
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Network Working Group W. Wimer
Request for Comments: 1532 Carnegie Mellon University
Updates: 951 October 1993
Category: Standards Track
Clarifications and Extensions for the Bootstrap Protocol
Status of this Memo
This RFC 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" for the standardization state and status
of this protocol. Distribution of this memo is unlimited.
Abstract
Some aspects of the BOOTP protocol were rather loosely defined in its
original specification. In particular, only a general description
was provided for the behavior of "BOOTP relay agents" (originally
called BOOTP forwarding agents"). The client behavior description
also suffered in certain ways. This memo attempts to clarify and
strengthen the specification in these areas.
In addition, new issues have arisen since the original specification
was written. This memo also attempts to address some of these.
Table of Contents
1. Introduction................................................. 2
1.1 Requirements................................................ 2
1.2 Terminology................................................. 3
1.3 Data Transmission Order..................................... 4
2. General Issues............................................... 5
2.1 General BOOTP Processing.................................... 5
2.2 Definition of the 'flags' Field............................. 5
2.3 Bit Ordering of Hardware Addresses.......................... 7
2.4 BOOTP Over IEEE 802.5 Token Ring Networks................... 8
3. BOOTP Client Behavior........................................ 9
3.1 Client use of the 'flags' field............................. 9
3.1.1 The BROADCAST flag........................................ 9
3.1.2 The remainder of the 'flags' field........................ 9
3.2 Definition of the 'secs' field.............................. 9
3.3 Use of the 'ciaddr' and 'yiaddr' fields..................... 10
3.4 Interpretation of the 'giaddr' field........................ 11
3.5 Vendor information "magic cookie"........................... 12
4. BOOTP Relay Agents........................................... 13
Wimer [Page 1]
RFC 1532 Clarifications and Extensions for BOOTP October 1993
4.1 General BOOTP Processing for Relay Agents................... 13
4.1.1 BOOTREQUEST Messages...................................... 14
4.1.2 BOOTREPLY Messages........................................ 16
5. BOOTP Server Behavior........................................ 18
5.1 Reception of BOOTREQUEST Messages........................... 18
5.2 Use of the 'secs' field..................................... 19
5.3 Use of the 'ciaddr' field................................... 19
5.4 Strategy for Delivery of BOOTREPLY Messages................. 19
Acknowledgements................................................ 21
References...................................................... 21
Security Considerations......................................... 22
Author's Address................................................ 22
1. Introduction
The Bootstrap Protocol (BOOTP) is a UDP/IP-based protocol which
allows a booting host to configure itself dynamically and without
user supervision. BOOTP provides a means to notify a host of its
assigned IP address, the IP address of a boot server host, and the
name of a file to be loaded into memory and executed [1]. Other
configuration information such as the local subnet mask, the local
time offset, the addresses of default routers, and the addresses of
various Internet servers can also be communicated to a host using
BOOTP [2].
Unfortunately, the original BOOTP specification [1] left some issues
of the protocol open to question. The exact behavior of BOOTP relay
agents formerly called "BOOTP forwarding agents") was not clearly
specified. Some parts of the overall protocol specification actually
conflict, while other parts have been subject to misinterpretation,
indicating that clarification is needed. This memo addresses these
problems.
Since the introduction of BOOTP, the IEEE 802.5 Token Ring Network
has been developed which presents a unique problem for BOOTP's
particular message-transfer paradigm. This memo also suggests a
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