Subject: Documentation for 169.254?

From: Paul Hoffman / VPNC <[email-masked]>
Date: Fri, 26 Oct 2001 11:44:12 -0700

Sorry to barge in with a technical, standards-related question. It
seems that there is a common practice that when a host asks for an
IPv4 address, such as through DHCP, but the host isn't attached to
the network, that the software gives it an address of 169.254.x.y. Is
this documented in any RFC? Should it be?

--Paul Hoffman, Director
--VPN Consortium

---

From: "Michael H. Warfield" <[email-masked]>
Date: Sat, 27 Oct 2001 23:08:41 -0400

> this documented in any RFC? Should it be?

	I couldn't find a reference to that netblock specifically in the
RFCs themselves but you might want to check out this:

	draft-ietf-zeroconf-ipv4-linklocal-04.txt

] 1. Introduction
] 
]    As the Internet Protocol continues to grow in popularity, it becomes
]    increasingly valuable to be able to use familiar IP tools such as ftp
]    not only for global communication, but for local communication as
]    well. For example, two people with laptop computers with built-in
]    wireless Ethernet may meet and wish to exchange files. It is
]    desirable for these people to be able to use IP application software
]    without the inconvenience of having to manually configure static IP
]    addresses or set up a DHCP server [RFC 2131].
] 
]    This document describes a method by which a host may automatically
]    configure an interface with an IPv4 address in the 169.254/16 prefix
]    that is valid for link-local communication on that interface. This
]    is especially valuable in environments where no other configuration
]    mechanism is available. The IPv4 network 169.254/16 is registered
]    with the IANA for this purpose. Allocation of link-local IPv6
]    addresses is described in "IPv6 Stateless Address Autoconfiguration"
]    [RFC 2462].

	I think this may be a good starting point for you.

> --VPN Consortium

	Mike
-- 
 Michael H. Warfield    |  (770) 985-6132   |  [email-masked]
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---

From: Bill Manning <[email-masked]>
Date: Sat, 27 Oct 2001 20:35:56 -0700 (PDT)

% 
% Sorry to barge in with a technical, standards-related question. It
% seems that there is a common practice that when a host asks for an
% IPv4 address, such as through DHCP, but the host isn't attached to
% the network, that the software gives it an address of 169.254.x.y. Is
% this documented in any RFC? Should it be?
% 
% --Paul Hoffman, Director
% --VPN Consortium
% 

It was documented a year after its delegation in a now expired draft
by Richard Troll.  There is an RFC that describes problems with auto
configuration using this prefix.  There is also a current draft in/from
zeroconf that talks about this prefix.  I've had a draft that describes
this prefix killed a couple of times by the IESG/IAB.  
The prefix was originally delegated after the LA IETF. You'll find a 
brief mention of the action on the last page fo the DHCP wg minutes.

-- 
--bill

---

From: [email-masked]
Date: Sat, 27 Oct 2001 21:28:28 -0700

This is discussed in some detail in the "zero-conf" IDs; I don't know 
that any are RFCs yet.

The intent is to mimic the "stateless autoconfiguration" in IPv6 in an 
IPv4 world.

Regards,

Justin

> this documented in any RFC? Should it be?
---
Justin C. Walker, Curmudgeon-At-Large  *
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