DHCP not always leasing IP

[Barry]

I have a problem with a W2K DHCP Server which is not
always leasing an IP address to a client.

The environment is as follows.

6 VLAN's

V1=10.0.41.x / 255.255.255.0 (DHCP)
V2=10.0.42.x / 255.255.255.0 (DHCP)
V3=10.0.43.x / 255.255.255.0 (DHCP)
V4=10.0.44.x / 255.255.255.0 (Static)
V5=10.0.45.x / 255.255.255.0 (DHCP)
V6=10.0.46.x / 255.255.255.0 (Static) (DHCP Server and
other Servers)

All IP address available in the DHCP leases are
reservations for valid clients.

The router has the iphelpers active on the connections
where dhcp is provided. The iphelper forwards DHCP
requests to V6 where the DHCP Server is located.

The clients are connected to the router via switches or
hubs. At switch level is controlled on which VLAN a
machine will be.

The problem is that certain machines will get an IP
address from the DHCP Server, but a machine on the same
VLAN (sometimes in the same room and connected to the same
switch) will not receive an IP address. (Error message
when manually trying ipconfig /renew is DHCP Server
unreachable)

We have used a sniffer to see what's happening on the
wire. The router forwards the dhcp discover request but
the DHCP server remains quit (no reply).

So it seems that the router is doing it's job but
somewhere along the line either the DHCP Server goes wrong.

Any help / ideas are welcome.

Rgrds,

Barry

 

[Brandon McHenry]

Curious but do these machines have 3Com NIC's with the 3C920 integrated
controller that is 3C905 compatible?