Re: [v6ops] Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)

Brian E Carpenter <> Thu, 07 January 2021 22:40 UTC

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Subject: Re: [v6ops] Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)
To: Philip Homburg <>,
Cc: IPv6 Operations <>
References: <> <> <> <> <> <> <> <> <> <> <>
From: Brian E Carpenter <>
Message-ID: <>
Date: Fri, 8 Jan 2021 11:40:23 +1300
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On 08-Jan-21 10:40, Philip Homburg wrote:
>> While I do agree that interface ID is much more closer to the truth, it
>> seems that one reason for zone rather than interface ID for link-locals in
>> RFC 4007 was to inform a multi-interface node that it had multiple
>> interfaces attached to the same link, informing it that the corresponding
>> interface link-local addresses are attached to the same link.
> Are there any implementation that do this? And in particular how does
> that work with the socket interface? I.e., with if_nametoindex and
> if_indextoname.

The machine on which I am typing has interface 6 and interface 22
both up and running.
On interface 6,  the default router is fe80::2e3a:fdff:fea4:dde7%6
On interface 22, the default router is fe80::2e3a:fdff:fea4:dde7%22

Yes, they are the same thing because the default router is also a transparent
Ethernet-to-WiFi bridge. Interface 6 and interface 22 both connect to
the same LAN, but the IP stack has no way to know it.

The zone index as described in RFC4007 is a hallucination.