On Sat, 11 Sep 2010 08:06:39 +0200 (CEST)
Mikael Abrahamsson <[email protected]> wrote:

> On Sat, 11 Sep 2010, Mark Smith wrote:
> 
> > How would you solve the problem? If you give end-nodes the ability to
> 
> Exactly the way it has been done for IPv4 with the mechanisms I've given 
> examples of before.

Your criticisms seemed to be architectural ones - that the IETF hadn't
designed a protocol that addressed these issues. So my question was how
would you solve it (architecturally)?

Layer 2 devices inspecting traffic isn't architecturally acceptable
because it's a layer violation, address rewriting or insertion isn't
because it takes away the end-node's peer status at the network layer,
which creates all the consequences we know of from v4 NAT. I don't
disagree about the costs of using point-to-point links (virtual or
otherwise) to quarantine end-nodes, however increased security usually
involves increased cost, so it is a security/cost tradeoff. The
advantage of point-to-point/quarantine model over other options is
that it both fits and maintains the existing architecture.

> L2 devices look at DHCPv6 etc and then enforce policy 
> accordingly. The thing here is that these mechanisms should have been 
> designed alongside IPv6 and all the "core" protocols in IPv6 should have 
> been designed with this in mind, making it easy and cheap for L2 devices 
> to find the traffic they need to look at.
> 
> Now whatever L2 devices need to look at is what is available, and some 
> isn't that easy to find and it might have to look at multiple things, some 
> of which is of no interest to it.
> 
> > If you truly don't trust the end-nodes at all to set their source 
> > address correctly, then quarantining them on individual point-to-point 
> > links would seem to me to be the only option that still allows other 
> > people in other environments to continue to trust end-nodes setting the 
> > source address.
> 
> *sigh* Taking the easy way out again. Point to point links are expensive.
> 
> Equipment doing q-in-q and/or PPPoE termination carry a hefty premium over 
> the ones who don't, especially if they need to handle thousands of 
> customers (ie thousands of interfaces). Compare this to a Cisco 3550 which 
> can route thousands of customers in a few subnets if needed.
> 
> -- 
> Mikael Abrahamsson    email: [email protected]
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