It does make sense though. Say one megabits interface with 20 VLANs. In that scenario, every VLAN, usually has own link-local address. It is more practical than "multiple interfaces with same link-local address." I found this on Juniper router and now assume it is Juniper specific implementation. Thanks all ----- Original Message ---- From: Scott Morris <swm@emanon.com> To: Erik Nordmark <erik.nordmark@sun.com>; snort bsd <snortbsd@yahoo.com.au> Cc: nanog@merit.edu; juniper-nsp <juniper-nsp@puck.nether.net> Sent: Tuesday, 29 January, 2008 12:36:55 PM Subject: RE: IPv6 questions And unless you are on only certain particular devices (e.g. L3 switches) then the end device won't necessarily have any relevant clue what VLAN it's on. I have never seen/heard of an RFC for it either and would certainly wonder "WHY?". :) Scott -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Erik Nordmark Sent: Tuesday, January 29, 2008 1:44 PM To: snort bsd Cc: nanog@merit.edu; juniper-nsp Subject: Re: IPv6 questions snort bsd wrote:

Never mind

it is the VLAN number. But which RFC define this?

I've never seen an IPv6 RFC specify to put the VLAN number in the link-local address. Thus this must be an (odd) choice made by some implementation. Perhaps the implementation somehow requires that all the link-local addresses for all its (sub)interfaces be unique, even though the RFCs assume that the implementation should be able to deal with multiple interfaces with same same link-local address. Erik

Thanks all

Dave

----- Original Message ---- From: snort bsd <snortbsd@yahoo.com.au> To: nanog@merit.edu; juniper-nsp <juniper-nsp@puck.nether.net> Sent: Monday, 28 January, 2008 3:05:59 PM Subject: IPv6 questions

Hi All:

With link-local IPv6 address, the converting from MAC-48 to EDU-64 address format (FF FE stuffing). How does the VLAN tags affect the conversion?

With the rule of FF FE stuffing, I can see clearly work on the ptp interfaces. But on those Ethernet based VLANs, it doesn't seem to follow that pattern:

Current address: 00:90:69:4a:b9:5d, Hardware address: 00:90:69:4a:b9:5d

well, i assume the link-local should be fe80::290:69ff:fe4a:b95d/64. actually, it shows:

Destination: fe80::/64, Local: fe80::290:6903:94a:b95d

how does the router get this 03 09 instead of ff fe?

Thanks all

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