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Re: Rethinking autoconfig, was Re: prefix length determination for DHCPv6
On Mon, 17 Sep 2007 14:57:17 +0200
Iljitsch van Beijnum <iljitsch@muada.com> wrote:
> On 17-sep-2007, at 14:36, Mark Smith wrote:
>
> > So what's wrong with using conventional or existing methods to address
> > or avoid this problem, such as reducing the layer 2 network size,
> > therefore reducing the number of nodes that can generate
> > multicasts, or
> > completely abandoning multicast/broadcast operation, by using NBMA
> > models?
>
> Obviously making good layer 2 networks is always a good idea.
>
> However, IPv6 really needs a multicast-capable network. In the
> absense of additional protocols, I wouldn't even know how to run the
> protocol without VERY extensive manual configuration over a non-broad
> (multi)cast lower layer network.
>
Well, that's what the IPv6 NBMA RFC describes how to automate, using
protocols / methods such as MARS and NHRP. Initially NHRP over Ethernet
seems a bit inconceivable however I was recently looking into NHRP
to better understand it, and found that Cisco implemented NHRP support
for Ethernet back as early as IOS v11.2. I think an implementation
existing, albeit for IPv4, indicates NHRP for IPv6 over Ethernet and
other BMA layer 2s could be a possibility.
From what I was reading last night, it seems that all that is needed to
bootstrap IPv6 over NBMA is the end-node can communicate with the MARS
host. Reserving a well-known unicast/anycast IPv6 and having it
pre-configured within the end node could probably be a way to avoid
having users enter the MARS address manually.
> > Redoing DHCP seems to me to be a lot of effort when I'd think adequate
> > and well known solutions to these sorts of problems already exist.
>
> I certainly don't want to "redo" DHCP. The only thing that I suggest
> is an alternative method of _starting_ a DHCPv6 exchange.
>
Oh, ok.
> > Having a look at the IPv6 NBMA RFC (RFC2491), connectionless
> > NMBA technologies, such as SMDS, are accommodated. Based on that, I'd
> > be guessing that wireless ethernet wouldn't be too hard to operate in
> > an NBMA model if necessary.
>
> Maybe some of the WIMAX folks could chime in? I understand that's NBMA.
>
Regards,
Mark.