DHCP Superscope Assigning Wrong Address to Clients Windows Server 2003
Posted on 2008-02-04
I have a Windows 2003 network switched using a collapsed core design with a Cisco 3560 as the core switch and standard 3com or Netgear non managed swithces at the edge. The network is divided into several VLANS (192.168.4.0/24, 192.168.5.0/24, 192.168.6.0/23, 192.168.8.0/24). The 3560 is configured to route traffic between the networks and this works perfectly. All servers are on the 8.0/24 network, all DHCP clients are located on the other networks. There ia a DHCP server on the 8.0/24 network configured with a superscope encompassing scopes for the 4.0/24, 5.0/24 and 6.0/23 subnets. Each VLAN interface on the 3560 is configured with an ip-helper address entry (DHCP relay agent) that points to the DHCP server. DHCP usually works fine. However if a user on the 5.0/24 network takes his laptop to a room on the 6.0/24 network the laptop will usually pick up an address from the 5.0/24 subnet which means that he can't access the network because he is plugged into an interface on the core switch with a 6.0/23 ip address. The only way that I can get a client to pick up the correct address reliably when it is moving between subnets is to disable all scopes other that the one which I want. This is causing us big problems. I'm usually pretty ok with networking but this one has me stumped. Can anyone out there help?