Subject: RE: 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 18:10:25 -0400

There are also other implementations that support this concept though the
exact syntax to add the routes is often different. That's why specifying
0.0.0.0 is desireable.

Note that with the CSR option as it is specified today, you COULD do this
very easily by simply sending Windows clients the router as their IP
address. However, that would mean the DHCP Server needs to generate the CSR
option on the fly since it needs to substitute the client's assigned IP
address for the router.

One reason I'd like the router = 0.0.0.0 convention is that it won't require
any special support in the server to do this. I'm sure if we DON'T do this,
someone will do it anyway by simply having the server do this.

By specifying 0.0.0.0, you set up a standard convention that prevents the
need for the server to change the option data and makes it easy for clients
to take whatever special action is needed for them to install these routes.

- Bernie Volz
  IPWorks, Inc

-----Original Message-----
From: Ted Lemon [mailto:[email-masked]]
Sent: Thursday, June 22, 2000 6:00 PM
To: DHCPv4 discussion list
Cc: DHCPv4 discussion list
Subject: Re: Quick Poll - RE: draft-ietf-dhc-csr-02.txt - Allow router
to be 0.0.0.0?

> 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?

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_

---

From: John Schnizlein <[email-masked]>
Date: Thu, 22 Jun 2000 20:43:08 -0400

Please persuade me that this will not cause any confusion 
with the common use of 0.0.0.0 as a default route.
It should not imply that the host infer proxy arp for all
addresses, following Ted's explanation below.
It should permit installing preferred routes through 
different routers on the directly-attached subnet.
John

At 06:10 PM 06/22/2000 -0400, Bernie Volz wrote:
>...
>By specifying 0.0.0.0, you set up a standard convention that 
>prevents the need for the server to change the option data and 
>makes it easy for clients to take whatever special action is 
>needed for them to install these routes.
>
>...