Subject: Re: a response to "A Simple Solution for IPv6 Multihoming"

From: "Steven M. Bellovin" <[email-masked]>
Date: Tue, 14 Sep 1999 19:25:21 -0400

In message <[email-masked]>, Bradley Rey
nolds writes:
> > > the function of address aggregation is independent of this imposed
> > > aggregation hierarchy.  simply take away the brain damaged aggregation
> > > mandates and allow service providers to aggregate their address space
> > > as deemed appropriate.  
> > 
> > Can you please explain this? Where is the document that describes
> > how aggregation is done without aggregatable addresses?
> > 
> >   Brian
> > 
> hmm.. core bgp tables are growing linearly and i haven't seen
> a document describing an IPv4 aggregation hierarchy.  how can that be?

It's called CIDR -- see RFC 1517-1519.

		--Steve Bellovin

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From: Bradley Reynolds <[email-masked]>
Date: Tue, 14 Sep 1999 20:08:54 -0400 (EDT)

> It's called CIDR -- see RFC 1517-1519.
that is not analogous in the least to the hierarchy imposed in the ipv6
addressing architecture.  cidr only specifies more possible subdivisions
of the addressing space which permits you to aggregate in more flexible
fashion. it does not mandate an aggregation hierarchy in the least.

please point me to the document that shows me where the registry id and
provider id are in the ipv4 address and i will withdraw my comments.

BR

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From: Bob Hinden <[email-masked]>
Date: Tue, 14 Sep 1999 17:29:12 -0700

BR,

>provider id are in the ipv4 address and i will withdraw my comments.

There are no "registry id" and "provider id" fields in IPv6 addresses.  

RFC2374 "An Ipv6 Aggregatable Global Unicast Address Format" replaced
RFC2073 (that contained these fields).

Regards,
Bob

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From: Bradley Reynolds <[email-masked]>
Date: Tue, 14 Sep 1999 20:45:23 -0400 (EDT)

> There are no "registry id" and "provider id" fields in IPv6 addresses.  

the terms are not so important (though of course mine were a bit dated :).

what is important is that there is hierarchy imposed here which 
allows for simple aggregation.  

this hierarchy has a benefit:  good aggregation
this hierarchy has a drawback: how do i multihome?

my question is to whether the current IPv4 scheme of letting the providers
choose how to aggregate their prefixes is broken and needs to be fixed by
this hierarchy. it is important to understand that the cost of this
hierachy is that it has eliminated multihoming as known to ipv4 people
today. (and we have no solution to this problem as of yet)

BR