IP address range

[Simon Hobson]

David W. Hankins wrote:

>  > ... the DHCP server will still NOT give an IP address to
>  > the client. The server MUST be able to associate the relay agent address
>>  with a subnet, which means that the relay agent address MUST be within a
>>  subnet that either hosts the client or is in a shared network with the
>>  client.
>
>This is correct but I want to be complete;
>
>In 3.1.0 (and as 3.0.x is end-of-life this means "all current
>releases"), we picked up support for the relay agent information
>option link selection sub-option.
>
>This means the relay agent can specify in 'giaddr' the address for the
>server to direct replies to the relay agent, and specify in the link
>selection sub-option the address to use to perform the "client
>attachment" algorithm.
>
>So a relay agent need not have an address on the subnet, or even that
>link.  It just needs to supply an address within that subnet in the
>link selection option (it doesn't need to own the address it supplies,
>it is just informational).
>
>So it is not precisely a MUST that the relay agent have an address on
>the subnet.

Hmm, interesting. It's going to be fun when vendors start doing that 
in their relay agents and no-one can figure what's happening as it 
"doesn't look right" !

-- 
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.