Re: [v6ops] Discussion of draft-ietf-v6ops-ula-usage-recommendations

Mark Andrews <marka@isc.org> Tue, 21 July 2015 15:26 UTC

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To: Alexandru Petrescu <alexandru.petrescu@gmail.com>
From: Mark Andrews <marka@isc.org>
References: <6153A91F-7E9A-4579-BA06-72964568D343@cisco.com> <55AE54D3.7070502@gmail.com>
In-reply-to: Your message of "Tue, 21 Jul 2015 16:18:59 +0200." <55AE54D3.7070502@gmail.com>
Date: Wed, 22 Jul 2015 01:24:34 +1000
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Subject: Re: [v6ops] Discussion of draft-ietf-v6ops-ula-usage-recommendations
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In message <55AE54D3.7070502@gmail.com>;, Alexandru Petrescu writes:
> 1. Brian suggested to recommend that globals should be there on the
> machines having ULAs as well, if I understand correctly.
> 
> But I think so only on some Hosts, mainly the Hosts of end users.
> 
> 2. the ULA RFC suggests a ULA prefix can be generated out of a MAC
> address.  That sixxs implementation does it.  Except it takes it too
> serious: it does not accept a MAC address which is not a real MAC
> address - in that oui.txt.  And random MAC addresses (for privacy)
> certainly are not in that oui.txt.

This is a ULA generator.  You do not need a MAC.

% dd if=/dev/random bs=7 count=1 | od -t x1 | awk '/0000/ {print "fd" $2 ":" $3 $4 ":" $5 $6 ; exit}'
1+0 records in
1+0 records out
7 bytes transferred in 0.000024 secs (293601 bytes/sec)
fd61:cb66:8851
% 

> ULAs because the only tool out there (sixxs) can't refuses a copy paste
> a MAC address from the widely used windows 7 laptops.

*All* you need is 7 bytes of random numbers.  Many modern CPU's
will do this for you today.  If you don't have that then you can
use the pseudo random number generator in the rfc.

The algorithm is for CPE devices without a good source of randomness.

> I am not sure what the problem is, but it's very good to have a very
> easy way to generate ULAs.
> 
> 3. in an enterprise deployment there was a problem of ULAs deployed in a
> intra-network and another ULA space in another intra-network, of the
> same enterprise.  So we wanted to make sure two things: the two ULA
> spaces are distinct, or otherwise make sure the gateway router does not
> route between the two intranets' ULAs (but yes, route between their
> respective GUAs).   I am not sure how to translate that into advice,
> because I am not sure how it will unfold in the near future.
> 
> Alex
> 
> Le 21/07/2015 16:02, Fred Baker (fred) a =E9crit :
> > https://tools.ietf.org/html/draft-ietf-v6ops-ula-usage-recommendations
> >
> >
> "Considerations For Using Unique Local Addresses", Bing Liu, Sheng
> > Jiang, 2015-05-03
> >
> > This draft came up from the floor this afternoon. I think we need
> > some concentrated constructive conversation regarding it - we have
> > had a lot of the other kind.
> >
> > What issues do we need to address to complete it. and what specific
> > recommendations would that include?
> >
> >
> >
> > _______________________________________________ v6ops mailing list
> > v6ops@ietf.org https://www.ietf.org/mailman/listinfo/v6ops
> >
> 
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Mark Andrews, ISC
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