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

Brian E Carpenter <> Tue, 21 July 2015 14:53 UTC

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Date: Wed, 22 Jul 2015 02:53:53 +1200
From: Brian E Carpenter <>
Organization: University of Auckland
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Subject: Re: [v6ops] Discussion of draft-ietf-v6ops-ula-usage-recommendations
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On 22/07/2015 02:18, Alexandru Petrescu wrote:
> 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.

All hosts that need external communication.

> 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.
> I think this is an undesirable situation to be in: unable to generate
> ULAs because the only tool out there (sixxs) can't refuses a copy paste
> a MAC address from the widely used windows 7 laptops.

That isn't a standards issue, but I agree that operationally, there needs
to be a viable way for anyone to generate a random number. Wait a minute,
that doesn't seem hard.

> 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). 

Why not? ULA to ULA routing on a private link might be desired
(e.g. after two networks merge without renumbering). From a routing
PoV there is nothing special about a ULA prefix; we just need to
configure carefully where it is routed and where it is not routed.

Anyway - I'd like to see the draft progress. Has it already had a WGLC?


> 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 écrit :
> "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
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