Windows ignoring DHCPOFFER is broadcast
Jamie Savage
jsavage at yorku.ca
Thu Mar 27 18:17:32 UTC 2008
Hi,
I have a situation where I have setup a subnet with DCHP
relay...ie....A Cisco router in this case with the subnet interface
config'd with the IP-helper command pointing to a DHCP server on another
subnet. I fire up my XP-SP2 laptop which starts looking for an IP
address. The 'remote' DHCP server sees the DHCPdiscover come in and sends
out a DHCPoffer which is broadcast out to the originating subnet. My
XP-SP2 machine sees the broadcast (which carries the laptops MAC address
buried in the Bootstrap Protocol portion of the frame) but ignores
it...ie...it does not send a DHCPrequest back. However, when I plug a
MAC (Leopard) laptop or a LINUX laptop into the same port....they
negotiate a DHCP address with no problem. Now, when I plug my XP-SP2
laptop into another subnet which also uses DHCP-relay but points to a
different DHCP server.....it works fine! However, in this case the
DHCPoffer is unicast specifically to the laptops MAC....ie....not
broadcast. . I would think that any client that sees a broadcast frame
with their MAC in the Bootstrap Protocol should respond. Should
DHCPoffers be unicast or broadcast or both?? Can someone point me in a
direction to start looking?....I'm not sure if this is a Windows issue, a
DHCP server issue or some networking issue.
.........thanks in advance............J
James Savage York University
Senior Communications Tech. 108 Steacie Building
jsavage at yorku.ca 4700 Keele Street
ph: 416-736-2100 ext. 22605 Toronto, Ontario
fax: 416-736-5701 M3J 1P3, CANADA
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