Subject: RE: draft-ietf-ipngwg-scopedaddr-format-00.txt

From: Brian Zill <[email-masked]>
Date: Tue, 26 Oct 1999 13:58:20 -0700

I agree that it would be beneficial if we all used the same textual
representation for scoped addresses.

I'm not very particular as to how we do this, but I think the scope id
should come first (and not after the address).  Textual representation of IP
addresses has always been big-endian, where the most significant portions of
the address come first.  And there is also already the precedent of putting
port numbers after an address (using a : for a separator) which goes along
with this (port numbers can be viewed as the least significant part of an
address).  Since the scope id is the most significant part, it should be
written before the rest of the address.

> PS: I like the '-' character as a delimiter ('@' is already used for
> other purposes).

This could rapidly turn into the same argument regarding reserved characters
and the lack of any remaining unused ones that we had over URL
representation of addresses.  But I agree that @ is particularly bad.  The
'-' character sounds reasonable to me.  We currently use the '/' character
(i.e. scopeid/address) in our implementation, but it'd be easy to change to
scopeid-address.

--Brian
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From: JINMEI Tatuya / 神明達哉<[email-masked]>
Date: Thu, 28 Oct 1999 01:26:49 +0900

>>>>> On Tue, 26 Oct 1999 13:58:20 -0700, 
>>>>> Brian Zill <[email-masked]> said:

> written before the rest of the address.

I'd not necessarily oppose your opinions above, but please let me
explain my impression.

Is it so obvious that the scope_id part is the most significant part?
I'm not sure. It seems to me that we could recognize (for example) a
link-local address as follows:

1. Look at the 1st 16 (or at least 10) bits of the address (fe80) and
   recognize that this is a link-local address. i.e. this is the most
   significant part.
2. Then look at the scope identifier and recognize to which link the
   address should belong. (In this scenario, the scope id is the 2nd
   significant part)
3. Finally use the host id part of the address (i.e. the last 64 bits)
   to identify the node that the address specifies in the link.

So I feel the appropriate portion for the scope_id is subtle. However,
I don't stick to the idea that the scope id should be after an
address. I'd respect others' opinions.

> (i.e. scopeid/address) in our implementation, but it'd be easy to change to

Through the discussion so far, '@' seems bad for the delimiter and '-'
seems acceptable. Does anyone have any other suggestions?

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					[email-masked]
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From: [email-masked]
Date: Thu, 28 Oct 1999 07:11:53 +0900

>seems acceptable. Does anyone have any other suggestions?

	I do not want to start holy war, but "-" is used in many place
	where we say address ranges, like
		10.1.1.1-10.1.1.254
	so I fear "-" is not a good bet from porting aspect.

itojun

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From: Francis Dupont <[email-masked]>
Date: Fri, 29 Oct 1999 20:41:34 +0200

In your previous mail you wrote:

=> this is the only example where "-" doesn't fit very well
(but scope is needed for this kind of context, for instance
link1/fe80::1-fe80::2 is far better than fe80::1-fe80::2
(I reuse Richard's notation but I prefer to put scopes after
than before...)

Regards

[email-masked]

PS: for IPv6 in general, prefixes are more used than address ranges.