Maybe I'm confused, but I don't see what L=0 really means. If ADDRCONF
assigns the prefix to the interface, then the prefix is on link for at least
one node, the node that configured the interface with the prefix. I suppose
one could argue that, even if that node considered the prefix on link, that
node should not assume another node does. But IFICT, 2461 doesn't have
specific, RFC 2119 requirements language around that.
If M=1, and stateful configuration is used, then I could see some sense in
L=0, since I assume in that case the prefix is not assigned to the
interface.
Can anybody say what real implemetations do with this?
----- Original Message -----
From: "Templin, Fred L" <[EMAIL PROTECTED]>
To: "Julien Laganier" <[EMAIL PROTECTED]>; "James Kempf"
<[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>; "INT Area" <[EMAIL PROTECTED]>; "IETF IPv6 Mailing
List" <[email protected]>
Sent: Thursday, August 31, 2006 10:40 AM
Subject: RE: [netlmm] Multilink Subnet Considerations for NETLMM Addressing
In addition to what Julien said, (RFC2461, Section 6.3.4)
also says:
"Prefixes with the on-link flag set to zero would normally
have the autonomous flag set and be used by [ADDRCONF]."
and ([ADDRCONF], Section 5.5.3) looks only at the 'A' bit
for address configuration. Hosts use prefixes with the 'A'
bit set to configure an address and add it to the list of
addresses assigned to the interface regardless of the sense
of the 'L' bit.
Fred
[EMAIL PROTECTED]
-----Original Message-----
From: Julien Laganier [mailto:[EMAIL PROTECTED]
Sent: Thursday, August 31, 2006 1:43 AM
To: James Kempf
Cc: [EMAIL PROTECTED]; INT Area; IETF IPv6 Mailing List
Subject: Re: [netlmm] Multilink Subnet Considerations for NETLMM
Addressing
Hi James,
Just for clarification.
On Thursday 24 August 2006 20:04, James Kempf wrote:
Fred,
I don't think this quite captures the situation.
[...]
Secondly, exactly what is meant by 'L=0' is underspecified by RFC
2461. I think everyone agrees with 'L=1' means, that the prefix is
only being advertised to nodes that are on this physical link. Any
effort to tighten up the definitoin of 'L=0' is going to need
wider discussion with the ipv6 WG and possibly might impact
RFC2461bis. This draft is currently in AD Evauation:Revised Draft
Needed.
[...]
I wouldn't say that 'L=0' semantic is underspecified. I on the
opposite found 2461 to be quite well specified. It says:
Note, however, that a Prefix Information option
with the on-link flag set to zero conveys no information concerning
on-link determination and MUST NOT be interpreted to mean that
addresses covered by the prefix are off-link.
That is, it doesn't mean that *all* nodes are off-link. Some might,
while some might not. But it clearly specifies what the node should
do in that case.
The default behavior (see
Section 5.2) when sending a packet to an address for which no
information is known about the on-link status of the address is to
forward the packet to a default router;
i.e. send packets to the default router.
What do you think is underspecified?
--julien
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