Subject: Quick Poll - RE: draft-ietf-dhc-csr-02.txt - Allow router to be 0 .0.0.0?

From: Bernie Volz <[email-masked]>
Date: Thu, 22 Jun 2000 17:02:03 -0400

Folks:

I have suggested to Ted that he consider adding text to Classless Static
Routing (CSR) draft to allow the router IP address to be 0.0.0.0 for some
routes. If the router IP address is 0.0.0.0, the client (if it supports it)
should install a route such that the destination is directly reachable on
the interface being configured.

The concept behind this is that it easily allows for probably one of the
most useful proposes of routing information to be given to clients in the
first place. That of supporting multiple subnets on the same physical wire.
This is often a difficult issue since there is no standard (at least to my
knowledge) for ICMP Redirects to communicate this.

If a client does not support the concept of such routes, it would ignore
that particular route.

Ted is somewhat cautious about adding this text as there is no precedent for
it anywhere else yet and he (as I) would like to see the CSR draft go to the
IESG as soon as possible.

So, how do people feel about this?
- Do you feel it is worth adding it?
- Do you fear it would delay the draft?
- Do you think it is a bad idea in the first place?

Thanks for your prompt attention.

- Bernie Volz
  IPWorks, Inc.

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From: John Schnizlein <[email-masked]>
Date: Thu, 22 Jun 2000 17:37:09 -0400

At 05:02 PM 06/22/2000 -0400, Bernie Volz wrote:
>... If the router IP address is 0.0.0.0, the client (if it supports it)
>should install a route such that the destination is directly reachable 
>on the interface being configured.

You mean the host would ARP for the destination even though this host
does not have an IP address on that subnet?

If the host has an IP address on each subnet it is on (even if through
the same interface) wouldn't it use its local routing function (not
forwarding) to do the right thing on directly-attached subnets?

John

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From: Ted Lemon <[email-masked]>
Date: Thu, 22 Jun 2000 14:59:54 -0700

> forwarding) to do the right thing on directly-attached subnets?

The point is to be able to support more than one subnet on the wire
without requiring hosts on the same wire to send packets to other
hosts on the same wire through a router.  DHCP doesn't provide a
standard way to give a client more than one IP address per network
interface, nor would you want to.  So you can't really use the usual
routing mechanism.

What this is is a limited form of the proxy arp feature in Windows,
where if you give a windows machine its own IP address as a default
route, it ARPs for every IP address it tries to contact, whether or
not that IP address is on its local subnet.

			       _MelloN_

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From: Ralph Droms <[email-masked]>
Date: Mon, 26 Jun 2000 20:51:35 -0400

I would be inclined to specify the list of networks local to the
interface as a separate option.  It's different information
(and should be carried in a different option), there's no need
to carry the 4 bytes of zeroes with every entry and it would slow
down draft-ietf-dhc-csr-02.txt.

- Ralph