Subject: Re: (ngtrans) An IPv4 anycast address for 6to4<->6bone gateways

From: Simon Leinen <[email-masked]>
Date: 02 Nov 2000 11:02:27 +0100

>>>>> "bh" == Brad Huntting <[email-masked]> writes:
> 6to4 gateways would advertise to the their IPv4 peers that they have
> a route for "a.b.c.d".  And for their IPv6 peers (the 6bone) they
> can advertise a route for 2002::/16.

> Does anyone see a problem with this?  I dont suppose there's already
> a block of IPv4 address space set aside for anycast?

I think nobody has really been using IPv4 anycast on a global
(inter-provider) scale.  The IETF dnsop working group is conducting an
experiment on global anycast, with the possible application of name
servers for important zones such as the root, see
draft-ietf-dnsop-ohta-shared-root-server-00.txt
(http://www.switch.ch/lan/dns/references.html#aroot for a pointer).

Each new anycast address means additional routing entries in the
default-free zone.  Personally I'm not sure whether the ability to
have a standard IPv4 address for the 6to4/6bone gateways is enough to
justify this (the current Web page is a good alternative).  One might
be tempted by the idea that making global IPv4 routing more difficult
would be a good thing to promote the deployment of IPv6, but this
could also backfire.

Regards,
-- 
Simon.

---

From: Brad Huntting <[email-masked]>
Date: Thu, 02 Nov 2000 07:55:16 -0700

> have a standard IPv4 address for the 6to4/6bone gateways is enough
> to justify this (the current Web page is a good alternative).  One
> might be tempted by the idea that making global IPv4 routing more
> difficult would be a good thing to promote the deployment of IPv6,
> but this could also backfire.

The sort of things I'm imagining will need this pre-defined default
route for 6to4 are boxes alot like the simple NAT boxes we have
today.  You plug them in and they work.  They appeal to the sort
of user who's VCR flashes 12:00.

As for routing table size, the last big stink I remember was when
Sprint desided to filter CIDR exceptions for blocks beyond 206.0.0.0.
But shortly after that the price of memory droped dramatically.
So, I dont think most NDZ routers will have any trouble with a
hundred anycast routes.

brad

---

From: Keith Moore <[email-masked]>
Date: Thu, 02 Nov 2000 11:37:26 -0500

> justify this (the current Web page is a good alternative). 

I don't think that the cost of a single extra entry in the routing table
is so great, especially since it could do a lot to make IPv6 deployment
easier.  And as compared to the web page, the anycast approach has the 
advantages that it requires little or no manual configuration (it can 
be the default) and that it can automatically adapt to changing network
conditions.

Keith

---

From: Brian E Carpenter <[email-masked]>
Date: Thu, 02 Nov 2000 15:26:03 -0600

And as Brad said, we need this to be as close to self-configuring as
possible.. which excludes users having to go to a web page. (OK, a daemon
could go to a web page, but surely anycast is more robust than that.)

   Brian

Keith Moore wrote:
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-- 
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Brian E Carpenter 
Program Director, Internet Standards & Technology, IBM 
On assignment for IBM at http://www.iCAIR.org 
Board Chairman, Internet Society http://www.isoc.org
Non-IBM email: [email-masked]