LAN Manager bootdisk booting with DHCP does not work correctly.

m.taljaard · ‎09-27-2002

Customer has the following setup.

Switched network. Clients in VLAN1 and DHCP server in VLAN 2. IP helper-address specified. DHCP is working.

Scenario 1: When PC on Vlan1 boots up, DHCP request is relayed by the IP helper-address on the Cisco router and the DHCP address is received from the DHCP server on VLAN2. PC gets his address and all required fields and connectivity is 100%. So scope is correct, no secondary address is used and the DHCP server is configured correctly.

Scenario 2:When the customer boots the PC on Vlan1 with TCP/IP LAN Manager bootdisk configured for DHCP and uses a Microsoft DHCP relay agent the address is assigned and the PC connectivity is 100%.

Scenario 3:When the customer boots the PC on Vlan2 with TCP/IP LAN Manager bootdisk configured for DHCP and no DHCP relay is required as the PC and the DHCP server is on the same segment. IP address is assigned and PC connectivity is 100%.

Scenario 4:Customer boots PC on Vlan1 with TCP/IP LAN Manager bootdisk configured for DHCP and the DHCP Packet is seen on the router and received and sent by the DHCP server. The PC rejects the DHCP reply.

This does not make sense. The customer has tested it with a Ghost bootdisk as well and found the same conditions.

IT works with the Microsoft DHCP Relay agent, but not with the Cisco DHCP relay (ip helper-address).

ANY ADVICE?

m.taljaard · ‎10-01-2002

The solution is simple, but this it can be tricky.

Under the Cisco interface the broadcast address was specified.

The DHCP reply is sent to the address x.x.x.255 and not 255.255.255.255.

The Microsoft DHCP relay used 255.255.255.255 for the DHCP reply.