[ppml] EUI-64 and autoconfig & RA vs DHCPv6 (Was: Those pesky ULAs again)

[Jeroen Massar]

Leo Bicknell wrote:
> In a message written on Wed, May 30, 2007 at 12:56:15PM -0700, John Pau=
l Morrison wrote:
>>    I'm curious about the opposition to EUI64. The process for numberin=
g
>=20
> It's quite simply the worst of all worlds.  Pick your reason:

[couple of good points snipped above and below ;) ]
> * Getting just an address is useless.  You can't even browse just the
>   web without nameservers as well.
> * The system is not extensible to other attributes, so it has to be
>   thrown out entirely. (DHCP6)

There is an RA bit which says "look at another managed/stateful
protocols" (AdvManagedFlag + AdvOtherConfigFlag in radvd.conf), so you
don't throw it out completely, but indeed you do replace it mostly.

A lot of people use DHCPv4 + RA for IPv6, which saves on doing extra
configuration for DHCPv6, also because not all the client/server tools
are there yet I guess.

Note that newer versions of radvd include the following config option:
8<--------------------------------------------------------------
       RDNSS (Recursive DNS server) definitions are of the form:

       RDNSS ip [ip] [ip] {
            list of rdnss specific options
       };
-------------------------------------------------------------->8
So what you state is not entirely true

> * Users with servers are going to fixed assign them, in order, from the=

>   bottom, because they put in static DNS, IP's in load balancers, and s=
o
>   on.  The protocol dictates these uses waste on the order of 56+ bits.=


True. BUT it is not the protocol that 'dictates' it. As Paul Vixie
mentioned, you can simply use /124's or whatever. That is your pick,
it is your network after all and there you are king, queen and ruler.

RIR allocation policies currently do think of /64s + /48s respectively
for a link link and a site. As such folks will expect those sizes to
be allocated.


All that said. The EUI-64 autoconfig mode does come in handy in a
certain chunk of space: fe80::/64 - Link Locals. But indeed this does
not need to be used for the rest of the network. This part does solve
the dentist office network, just plug and play, no config required.

Greets,
 Jeroen


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