Re: draft-ietf-multi6-multihoming-requirements-03

[Joe Abley <jabley@automagic.org>]

On Tuesday, July 2, 2002, at 09:08 , Iljitsch van Beijnum wrote:

> On Mon, 1 Jul 2002, Joe Abley wrote:
>
> > It is common practice to number news, mail, and HTTP proxy servers
> > (tuned for retrieval of objects over satellite-like latencies) within
> > subnets which can be advertised such that inbound traffic from the rest
> > of the world arrives on those servers via a satellite link, whereas all
> > other traffic (including traffic directly aimed at subscriber 
> > addresses)
> > arrives via terrestrial fibre.
> Ok, nothing wrong with that. But BGP doesn't provide any functionality 
> to
> really help with this.
Well, BGP plus CIDR abuse does. If I operate 203.97.0.0/17, and I obtain 
transit from two providers as vaguely described, I can hang all my 
satellite-tolerant gear in (say) 203.97.2.0/24 and advertise just 
203.97.2.0/24 over the satellite circuit. The fact that I am able to 
advertise covered routes to make things work is central to the way that 
multi-homing is made to work with v4, and is one example of things we 
are trying to provide core-safe alternatives for in v6.


>  Since it can be done now without help from BGP,
> there is no reason an IPv6 solution should specifically cater to this
> need. Just not getting in the way of more specific routes or policy
> routing should be enough.
It seems feasible to me that there will be solutions to the requirement 
as currently stated on the draft that do not need to rely on policy 
routing or the advertisement of covered routes. I do not have such a 
solution in mind, but I don't see why we should discount the possiblity 
that one might exist.


> > I think the basic requirement should stay. I am not married to the 
> > words
> > currently in 3.1.4, however, so if you have better ones I'd be glad to
> > hear them.
> "Existing IPv4 multihoming practices can coexist with policy-based 
> routing
> and forwarding mechanisms. An IPv6 multihoming architecture should
> retain this capability."
As I said, I think that presupposes a solution.


Joe