Re: NT 3.51 dhcp client and server ip address

[Ralph Droms <[e-mail]>]

I suggest the following text as a new paragraph to follow the second
paragraph in draft-ietf-dhc-dhcp-08.txt:

The 'server identifier' field is used both to identify a DHCP server in a
DHCP message and as a destination address from clients to servers.  A
server with multiple network addresses MUST be prepared to to accept any of
its network addresses as identifying that server in a DHCP message.  To
accommodate potentially incomplete network connectivity, a server MUST
choose an address as a 'server identifier' that, to the best of the
server's knowledge, is reachable from the client.  For example, if the DHCP
server and the DHCP client are connected to the same subnet (i.e., the
'giaddr' field in the message from the client is zero), the server SHOULD
select the IP address the server is using for communication on that subnet
as the 'server identifier'.   If the server is using multiple IP addresses
on that subnet, any such address may be used.   If the server has received
a message through a DHCP relay agent, the server SHOULD choose an address
from the interface on which the message was recieved as the 'server
identifier' (unless the server has other, better information on which to
make its choice).   DHCP clients MUST use the IP address provided in the
'server identifier' option for any unicast requests to the DHCP server.

If pressed, I would also consider adding the following sentence to the
first paragraph of section 9.7 of draft-ietf-dhc-options-1533update-05.txt:

DHCP clients use the contents of the 'server identifier' field as the
destination address for any DHCP messages unicast to the DHCP server.

Comments?

- Ralph