Re: [v6ops] A proposal for draft-ietf-6man-rfc4291bis-07 - FE80::/10 and IID length

Alexandre Petrescu <alexandre.petrescu@gmail.com> Wed, 08 March 2017 14:23 UTC

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Subject: Re: [v6ops] A proposal for draft-ietf-6man-rfc4291bis-07 - FE80::/10 and IID length
To: otroan@employees.org
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From: Alexandre Petrescu <alexandre.petrescu@gmail.com>
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Date: Wed, 8 Mar 2017 15:23:54 +0100
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Le 08/03/2017 à 12:35, otroan@employees.org a écrit :
>>>> It would be good too if RFC4291bis said in a small place that
>>>> "FEBF::1 is a Link-local address too".
>>>
>>> No. It says the link-local prefix is FE80/10 + zeroes +
>>> interface-id. If you have a 118 bit long IID you can create the
>>> above link-local address, but that really does not have to be
>>> stated.
>>
>> But to let that happen, it should also refrain from picturing or
>> writing that IIDs must be of 64bit length.  If it needs to give
>> examples it should rather use "e.g. /118".
>
> Write an IPv6 over foo document with 118 bit IIDs.

Invitation considered.

> There is a good reason the prefix-length of the link-local address
> space is explicitly specified.

Well, I think there is no such reason.

> If all nodes on a link didn't agree on this value, you would get into
> problems with protocols using the link-local address.

Well, I dont think so.

> E.g. address resolution for the default router,

Well, address resolution: the default router sends NA including its 
source address.  It does not include a plen.

If the Host does not want to wait for the NA it will send an NS; this NS
does not include a plen either.

I dont know where do you see the need to agree on a plen for the LL
addresses?  Can I know?

> or sending packets from DHCP server to host...

Well... it's the same: NS and NA are needed, and these dont use a plen.

Besides, LL addresses are only valid on a link; so there is no need to 
perform some matching in the tables to identify whether should go to rt 
table or to neighbor cache (which would need plen, or otherwise exact 
match).

Alex

>>>> The fact that everybody always says "an FE80 is an LL", or "an
>>>>  LL is an FE80" does not mean FEBF::1 is not an LL too.  And
>>>> that has deep consequences to address plans.
>>>
>>> No it hasn't.
>>
>> Well...
>
> Ole
>