Subject: FW: DHCP server startup announcement

From: Bernie Volz <[email-masked]>
Date: Mon, 25 Sep 2000 08:04:20 -0400

Folks ... (I think there may have been a previous discussion on the V6 list
about this but I could be wrong), but should we not consider perhaps a
better model than having clients periodically send SOLICIT messages?

Perhaps a "Server-Started" message could be use instead? This would notify
clients that are on the link that a server is present and that they may want
to retry SOLICITs.

Now, while this works well for clients that are on the same physical link,
it is less clear how this would work when relays are included in the
configuration (especially if the relays are also not on the same physical
link as the server).

So, perhaps this is a brain-dead idea because of these issues.

- Bernie Volz

-----Original Message-----
From: Erik Guttman [mailto:[email-masked]] 
Sent: Monday, September 25, 2000 3:00 AM
To: DHCPv4 discussion list
Cc: DHCPv4 discussion list
Subject: Re: DHCP server startup announcement

Stuart Cheshire wrote:
> When a DHCP client fails to find a DHCP server, it typically keeps 
> broadcasting DHCP DISCOVERs at a low rate (e.g. one every five minutes).
...
> One thought that occurs to me is that we could borrow from 
> draft-ietf-dhc-pv4-reconfigure-01.txt -- the server could broadcast a 
> FORCERENEW (perhaps with all zeroes in the chaddr field) effectively 
> saying, "To any client that currently has no server-assigned address, and 
> would like one, a server is now available for you to send a DISCOVER."

I fully support this direction.  This will make it much easier for
auto configured clients to discover DHCP servers.  One of the problems
with the 'polling model' is that devices will discover the DHCP server
at different times.  During this 'transition' phase, some devices could
potentially be unable to communicate.  This could be avoided by having
devices discover the DHCP server through an announcement and transition
en masse.  Considering that - there should be some randomizing interval
so that hosts that receive the FORCERENEW don't all try to hit the DHCP
server at once :-)

Erik