Relay Subnet migration question

Robert Fisher rfisher at
Mon May 15 22:28:35 UTC 2006

I'm probably too dizzy to stop checking mailing list archives and 
actually ask this, but anyway ;-)

Basically, what I want to know is that is there some method that when a 
lease renewal
request is received for a range that is no longer valid in which a 
release and renew
attempt can be handled?  My guess is that this deals more with the 
client protocol and
individual vendor's implementations -- so this is mostly a request for 
clarification and a
prayer for a minor miracle :).

I'm dealing with a cable modem setup, so all the requests I'm concerned 
with are coming
through the relay agent.  I've already added the new subnet (subnetB) to 
my dhcpd.conf
and reconfigured the CMTS so that both the old (subnetA) and subnetB are 
on the same
physical segment, and that the CMTS now uses an IP from subnetB  for the 
giaddr on
relayed requests.  I'm also using a 6 hour lease which has been in place 
for several

Right now, I just have separate subnet declarations like:

subnet subnetA netmask {
    option routers A.B.C.1;
    option subnet-mask;
    range A.B.C.3 A.B.F.253;  # C, D, E, F from /22 mask for example

subnet subnetB netmask {
    option routers L.M.N.1;
    option subnet-mask;
    range L.M.N.2 L.M.Q.253;

If I remove the range statement from subnetA, I just receive an unknown 
lease message
in the log files. 

Does anyone have suggestions or clarifiactions for me?   I looked to 
but as the documentation states that there is no way to specify which 
subnet to use
and as far as I can tell, the Pool statements are only valid within 
subnet declarations
not from within the shared-network clause...

Thanks in advance,

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