NetBIOS Name Conflicts When NetBEUI Used on Multiple NICs

You can configure multiple network interface cards (NICs, also called network adapters) in a computer (multihomed) for use on the same network segment, but no two network adapters on the same segment in the computer can use NetBIOS. When you install NetBEUI on a multihomed computer, it violates this restriction.

When you install NetBEUI on a multihomed computer, NetBEUI binds to all available network adapters in the computer regardless of whether they are on the same physical network segment. If a computer containing two or more network adapters uses the same protocol on more than one network adapter in a given network segment, the computer sees duplicate computer names due to the resulting NetBIOS name conflict, generates an error, and fails to start system services correctly. This also occurs if both segments are bridged.

The event log may show an Event ID 2505 error (duplicate name on the network). The error may appear in the event log as either of the following messages:

• Event ID : 2505
  The server could not bind to the transport/device/netbt_<nic driver> because another computer on the network has the same name. The server could not start.
• Event ID : 2505
  The server could not bind to the transport/device/nbf_<nic driver> because another computer on the network has the same name. The server could not start.

The event log may also show:

• Event ID: 3870
  Source: workstation <computer name> is not a valid computer name.

This problem does not affect routable protocols (TCP/IP, AppleTalk and NWLink) because when you install or reconfigure them you have to choose a network adapter in Control Panel's Network configuration window, and this automatically disables the protocol's bindings to other adapters. When installing TCP/IP, for instance, you are forced to provide unique IP addresses to each network adapter, then choose one network adapter as the "Windows Networking Adapter" in the "Windows Networking on TCP/IP (NetBIOS)" box of the TCP/IP Configuration window.

You can manually configure multiple network adapters in a computer by disabling NetBEUI bindings to network adapters other than the one you want to use for the NetBEUI protocol. To do this, disable the following bindings:

• Server to NetBEUI protocol to <adapter driver> to <adapter>
• Workstation to NetBEUI protocol to <adapter driver> to <adapter>
• NetBEUI protocol to <adapter driver> to <adapter>
• NetBIOS Interface to NetBEUI protocol to <adapter driver> to <adapter>

When you have disabled all of these bindings, network operations can proceed.

For additional information, please see the following article(s) in the Microsoft Knowledge Base: