Exercise 5.2: Network Bindings

Exercise 5.2: Network Bindings

Objective: Become familiar with the process for enabling and disabling network bindings and changing network access order.

Estimated time: 10 minutes

In Chapter 2, you learned about NDIS and the concept of network bindings. A binding is an association between protocol layers that enables those layers to behave like a protocol stack. By binding a transport protocol such as TCP/IP (which operates at the Transport and Network levels) to a network adapter (which operates at the Data Link and Physical layers) you provide a conduit for the protocol’s packets to reach the network and thus enable the protocol to participate in network communications. NDIS lets you bind multiple protocols to a single adapter or multiple adapters to a single protocol.

1.	Click on the Start button and choose Settings/Control Panel. In Windows NT’s Control Panel, double-click on the Network application icon and choose the Bindings tab (see Figure 5.10).
2.	Click on the Show Bindings for down arrow to access the drop-down list. Note that you can display bindings for services, protocols, or adapters. A service bound to a protocol bound to an adapter provides a complete pathway from the local system to the network.
3.	Click on the plus sign next to the Workstation service. The Workstation service is the Windows NT redirector (refer to Chapter 1, “Networking Terms and Concepts”), which redirects requests from the local system to the network. The protocols currently bound to the Workstation service appear in a list below the Workstation icon. Click on the plus sign next to one of the protocols. The network adapters bound to the protocol now appear in the tree (see Figure 5.11).
4.	The protocols and their associated adapters represent potential pathways for the Workstation service to access the network. Windows NT prioritizes those pathways according to the order in which they appear in the Bindings tab. For the configuration shown in Figure 5.11, for example, Windows NT attempts to use the NetBEUI protocol with the Workstation service before attempting to use NWLink. The Move Up and Move Down buttons let you change the access order. Select a protocol under the Workstation service. Try the Move Up and Move Down buttons to change the position of the protocol in the access order. (Don’t forget to restore the protocol to its original position before leaving the Bindings tab.)

The Enable and Disable buttons let you enable or disable a protocol for a given service. Disable a protocol (for instance, NetBEUI) for the Workstation service. Now click the plus sign next to the Server service. Note that although the protocol is disabled for the Workstation service, it is still enabled for the Server service. Re-enable the protocol under the Workstation service and close the Network application.