Two IPs on one NIC
dhcp1 at thehobsons.co.uk
Wed Sep 16 15:30:58 UTC 2009
Alan Buxey wrote:
>does any DHCP client handle being given 2 addresses by DHCP?
>I thought the original request asked for DHCP from 2 ranges to be given..
>2 addresses can be handed out (and more!) from DHCPD but as far as I'm aware
>the client will check which address is valid for the link its on and
>then use it.... so unless its a case of 1 DHCP address and one static, then
>cant see this working
Wrong. Until the device is configured, it has no way of knowing what
address/subnet might be valid - that's what DHCP is for. It is the
server that will check which of several possible addresses are valid
for the clients network and offer something appropriate.
The problem is that the server could offer two different leases (but
not in one offer message) - the client would simply pick one and
ignore the other. There are two problems to be addressed - both need
doing at the client and that means you might as well just manually
configure the client !
1) The client need to make two requests, using different <something>
so the server will treat them as <different> and offer two different
leases. With the ISC server, the <something> would be client-id -
either two different values, or one value and not-present.
2) having got two leases, the client would need to configure both
addresses - that's going to require some significant hacking of the
code to cope with all the permutations
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