[114283] in North American Network Operators' Group
Re: Where to buy Internet IP addresses
daemon@ATHENA.MIT.EDU (Jack Bates)
Tue May 5 15:50:14 2009
Date: Tue, 05 May 2009 14:49:01 -0500
From: Jack Bates <jbates@brightok.net>
To: nanog list <nanog@nanog.org>
In-Reply-To: <alpine.DEB.1.10.0905052120230.22851@uplift.swm.pp.se>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Mikael Abrahamsson wrote:
> Why wouldn't DHCPv6-PD work within the home as well as between the ISP
> and the home?
>
DHCPv6-PD requires manual configuration.
> I see little reason why the main home gateway can't get a /56 from the
> ISP, and then hand out /62 (or whatever) to any routers within the home
> that asks for PD?
>
Sure, but how does the router know it needs to hand out a /62? Then what
about the router after that? Does it hand out a /61? then the router
behind that?
What if the ISP only gave a /60?
The problem with automatic arbitrary splitting of a prefix into smaller
prefixes is that the entire topology is unknown. In such a case,
bidirectional communication is useful, as is multiple prefix assignments
to a single node generated from chaining DHCPv6-PD requests.
PD is not designed for multiple stage delegations without manual
configuration for each stage.
Even the PD clients I tried on linux failed horribly in how they
assigned a prefix to the interfaces. One of them just took the prefix
length and divided it by the number of interfaces. Another, which I
ended up using allowed you to set the bits to use as a subnet, but that
meant you had to know the length from the ISP, and then the desired
length on each of the interfaces to set the appropriate SLA (ie, I
couldn't tell it I want a /64 on the interface, but instead had to tell
it the SLA is 4 bits, which from a /60 would give a /64, but if I
received a /56 it would break and have to be changed to 8 bits).
-Jack
