Subject: RE: [dhcwg] Defining failover scenario

From: "Bernie Volz (EUD)" <[email-masked]>
Date: Mon, 8 Oct 2001 20:58:35 -0500

Simple ... on a LAN place a DHCP server at each end. Place clients between the servers. Cut the cable somewhere in the middle. Now, some of the clients can talk with one server, some can talk with the other. The servers can't talk with each other (nor can all clients).
 
In today's switch environments, this can happen if you have two switches and have a DHCP server connected to each and some clients connected to each. Cut the cable between the two switches.

-----Original Message-----
From: Drew Baron [mailto:[email-masked]]
Sent: Monday, October 08, 2001 7:55 PM
To: [email-masked]
Subject: [dhcwg] Defining failover scenario

The failover draft  <draft-ietf-dhc-failover-09.txt> lists the following as a challenging scenario:

3.4.2.  Network partition where DHCP servers can't communicate but each
can talk to clients:
"First, due to a network failure, the primary and secondary servers cannot
   communicate.  As well, some of the DHCP clients must be able to com-
   municate with the primary server, and some of the clients must now
   only be able to communicate with the secondary server."

The phrase 'some of the clients' is tripping me up.  I'm struggling to envision the scenario needed to end up in this state.  Can anyone provide a concrete example of an environment that this could occur in?  How do I end up with clients that are on the same segment that cannot reach both servers?
 
Thanks,
-Drew Baron