Same MAC address on two VLANs & subnets

[Gerald Vogt]

Hi!

Just to verify I understand correctly how the dhcp server is working.

I have a DHCP 4.2.3-P2 server serving clients in various subnets, each
subnet in a separate VLAN. The server is multi-homed through a 802.1q
trunk serving some VLANs directly and some through DHCP relays. This
is working fine.

I have a Windows 7 computer which is also multi-homed in two VLANs
through a 802.1q trunk (on the same NIC). It gets the IP address on
both VLANs with DHCP.

DHCP requests from Windows on either VLANs come from the same MAC
address with the same hardware address and the same client identifier.

As the DHCP server only allows one active lease for each hardware
address/client identifier this means the windows 7 computer cannot
have two active leases, one in each VLAN/subnet. Only the last ACKed
DHCP request is active. Thus if the computer first gets an ip1 in
subnet1 on vlan1 and next gets ip2 for subnet2 on vlan2, the lease for
ip1 goes into free state again.

There is no server side solution to this problem at this time. The
only possible solution would be on the client side to make it send
different client identifiers.

Am I understanding this correctly?

Or is there a configuration option which I have missed?

Thanks,

Gerald