Subject: Re: LLMNR authorized range

From: bill <[email-masked]>
Date: Sat, 20 Mar 2004 12:12:48 -0800 (PST)

> > > From: Bernard Aboba <[email-masked]>
> > >
> > > ... If we are
> > > talking about IPV6, then Router Advertisement enables
> > > the host to become aware of the multiple subnets,
> > 
> > Terminology confusion? What subnets are in RA? RA can have multiple
> > prefixes to be used on the link (if L=1), but they are not subnets.
> 
> Uh? There is no official definition of subnet, but the generally agreed
> definition is "the set of addresses that shares a specified prefix".

	That is not generally agreed on in most circles I run in.
	The working definition here is: "a single broadcast domain"
	e.g. more layer two'ish.

> -- Christian Huitema

--bill

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From: Rob Austein <[email-masked]>
Date: Sat, 20 Mar 2004 16:18:45 -0500

> 	The working definition here is: "a single broadcast domain"

I think you're both right, but Christian's righter.

IP "subnets" (the term's a bit dated given CIDR, but comes from the
old subnetting extension to the original class A/B/C extension to the
original original IPv4 address architecture's static 255.0.0.0 network
mask) are an IP (layer 3) concept referring to a set of IP addresses
sharing a particular prefix.  The fact that IP subnets usually (but
not always) map 1-to-1 with link-layer broadcast domains has led to
sloppy terminology even in the IP world, and there are certainly other
uses of the term "subnet" which mean something entirely different (eg,
at one point I think the entire ARPANET was referred to as a "subnet"
of the ARPANET/MILNET system, and some link layer specs do use the
term "subnet" to mean link layer broadcast domain, as Bill suggests).

So for precision you have to state the context (including layer) in
which you're using the term, but since this is the IETF, and around
here we mostly talk about IP, any use of the term "subnet" in IETF
documents should generally be presumed to be talking about IP
addresses with a shared prefix unless stated or proven otherwise.

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From: Masataka Ohta <[email-masked]>
Date: Sun, 21 Mar 2004 08:07:45 +0900

Rob Austein;

> I think you're both right, but Christian's righter.

No, Christian is not.

According to the CATENET model of the Internet, the Internet
is composed from local networks (of RFC791).

	local network = subnet = link = broadcast domain

The proper way to assign a local network multiple addresses
is to let all the hosts (of RFC791) in the local network
share multiple prefixes of equal length using identiral
host parts (intra-subnet) addresses, which still means

	local network = subnet = link = broadcast domain

Confusions caused by any other configuration are the
problems of the configuration. The configuration is
responsible to make the model visible from other protocols

	local network = subnet = link = broadcast domain

> any use of the term "subnet" in IETF

It's "shared prefixes", not "a shared prefix".

						Masataka Ohta

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From: bill <[email-masked]>
Date: Sat, 20 Mar 2004 12:12:48 -0800 (PST)

--bill

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From: Rob Austein <[email-masked]>
Date: Sat, 20 Mar 2004 16:18:45 -0500

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From: Masataka Ohta <[email-masked]>
Date: Sun, 21 Mar 2004 08:07:45 +0900

Rob Austein;

No, Christian is not.

						Masataka Ohta