Re: WG Last Call: draft-ietf-v6ops-unmaneval-01.txt

[Pekka Savola <pekkas@netcore.fi>]

On Thu, 11 Mar 2004, Erik Nordmark wrote:
> Section 4.1 says
>    An ND proxy can also be used to extend a /64 prefix to multiple
>    physical links of different properties (e.g, an Ethernet and a PPP
>    link).
>  
> But isn't this solving a non-problem?
> Today in IPv4 (where a prefix is delegated to e.g. a SOHO customer)
> this doesn't seem to be an issue; either separate addresses are assigned
> to the PPP link, or the PPP link ends up being unnumbered.
> 
> Why don't those approaches apply to IPv6?

PPP doesn't support v6 prefix delegation, and there is no will to make
it so.  Does v4 either?  (I'm not sure -- but maybe that's some vendor
extension.)

This approach works in the case where the ISP is advertising you an
IPv6 prefix using RA, and you want to extend it to another subnet.
On the other hand, in IPv4, there are no such advertisements.  Either 
the prefix is delegated somehow, or you use NAT.
 
> Section 4.1.1 talks of a larger unmanaged network.
> But why do we think we need IPv6 specific solutions to this problem?

Because with IPv4 we have NAT.. which is sad but true -- it's used 
precisely in a scenario like this... (Of course, v4 also has 
proxy-arp, but that's used less and less now that there are easier 
solutions such as NAT available..)
 
> If IEEE 802 bridges are not ideal maybe either we should tell this
> to the IEEE, or pursue the various ideas that where discussed in the
> ZEROUTER BoF a while back. Locking us into ndproxy as a solution to
> a problem that no IETF WG has carefully looked at seems unwise.

I don't think we're locking into a solution -- but giving flexibility 
to pick either explicit prefix delegation or ND proxying, whichever 
seems suitable.
 
> Based on these concerns of mine, I disagree with recommendation #2.

What would you suggest as an (easy) replacement for v4 NATs?  ND 
proxying seems like an obvious solution in a scenario like this (that 
is, when pure bridging does not work).

So, I'd appreciate if you could elaborate on this .. and if possible, 
provide text/clarification you'd like to see in the document to bring 
out the concerns better.


-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings