Subject: [RFC 4862] about hardware address

From: Yukiyo Akisada <[email-masked]>
Date: Fri, 11 Jan 2008 09:52:27 +0900

Hi, all.

I have a question about RFC 4862 Section 5.4.5.
Please let me confirm about it.

It says,

    909    If the address is a link-local address formed from an interface
    910    identifier based on the hardware address, which is supposed to be
    911    uniquely assigned (e.g., EUI-64 for an Ethernet interface), IP
    912    operation on the interface SHOULD be disabled.

Does the word 'hardware address' here mean MAC address itself?
Or the address which is assigned physically at the factory?

I'm concerning that some system can change MAC address by software and
can use software-based MAC address.

When DAD fails for IP address based on software-based MAC address,
should the system disable IP operation on also that interface?

Thanks,

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Yukiyo Akisada <[email-masked]>

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From: JINMEI Tatuya / 神明達哉<[email-masked]>
Date: Thu, 10 Jan 2008 18:36:06 -0800

At Fri, 11 Jan 2008 09:52:27 +0900,

> Or the address which is assigned physically at the factory?

I'd say it's the latter, according to the background idea of this rule
(which is described in that same section).  Consider the case where
two different hosts located in the same link are manually configured
with the same Ethernet (MAC) address and the same link-local address
is configured for these two interfaces.  Then DAD will detect the
duplication of the link-local address, implicitly revealing the
conflict of the MAC address.  This section intends to detect such a
case and avoid subsequent disruption caused by keeping the conflicted
MAC address.  Whether it's a "real" hardware address or not doesn't
matter in this sense.

So,

> should the system disable IP operation on also that interface?

the answer to this question is YES.

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JINMEI, Tatuya
Internet Systems Consortium, Inc.

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From: JINMEI Tatuya / 神明達哉<[email-masked]>
Date: Thu, 10 Jan 2008 19:26:38 -0800

At Thu, 10 Jan 2008 18:36:06 -0800,

> I'd say it's the latter, according to the background idea of this rule

Sorry, I made a very confusing typo: I meant "it's the former".

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JINMEI, Tatuya

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From: Yukiyo Akisada <[email-masked]>
Date: Fri, 11 Jan 2008 12:58:55 +0900

Hi, Jinmei-san.

Thank you very much.

Now I'm really clear.

Regards,

On Thu, 10 Jan 2008 19:26:38 -0800