How to Reset the TCP/IP Stack to Fix Wireless Networking Problems

Reset the TCP/IP stack using "netsh init ip reset" in most cases clears
things up.

Network Connections Folder

The Network Connections folder and the Windows XP notification icons provide information about the state of the authentication. If an authentication requires additional information from the user, such as selecting one of multiple user certificates, a text balloon appears instructing the user. Within the Network Connections folder, the text under the name of the connection corresponding to the wireless network adapter indicates the status of the connection.

In Windows XP Service Pack 2 (SP2), the Repair capability has been enhanced for wireless connections. You can access the Repair capability through the Repair context menu option of a connection or from the Repair button on the Support tab of the Status dialog box of a connection. When you repair a wireless connection, it is disabled and re-enabled, which clears many error conditions on wireless network adapters.

When a wireless client running Windows XP with SP2 attempts a wireless connection, it goes through the following authentication states, which are indicated as the status of the wireless connection in the Network Connections folder, and in the new wireless connection Status dialog box, and in the Wireless Network Connection dialog box:

• Validating identity Credentials are required for connecting to the wireless network.

• Attempting to authenticate Credentials are being exchanged with the wireless network to authenticate a wireless connection.

• Authentication did not succeed The credentials for connecting to the wireless network were not valid and authentication has failed.

• Connected The credentials for connecting to the wireless network are valid.

Once authentication has succeeded, a wireless client running Windows XP with SP2 then attempts to obtain a valid IP address configuration and goes through the following states, which are indicated as the status of the wireless connection in the Network Connections folder, and in the new wireless connection Status dialog box, and in the Wireless Network Connection dialog box:

• Acquiring network address An IP address configuration is being obtained using the Dynamic Host Configuration Protocol (DHCP).

• Limited or no connectivity A DHCP server was not contacted and an Automatic Private IP Addressing (APIPA) address from the range 169.254.0.0/16 was assigned. This state is not shown for wireless ad-hoc networks, which typically do not have DHCP servers. Instead, the status of the connection is displayed as "Connected."

• Connected A DHCP server was contacted and a valid IP address configuration was obtained.

These improvements give the user and the network troubleshooter more information about how the wireless connection is progressing, from the initial association to the allocation of a valid IP address.

If the wireless connection obtains an APIPA address, Windows XP with SP2 warns you with the following message in the notification area of the desktop: "The connection has limited or no connectivity. You might not be able to access the Internet or some network resources. For more information, click this message." When you click on the message, Windows XP displays the Support tab of the Status dialog box for the wireless connection, from which you can view additional details or attempt to repair the connection.

Additionally, when you obtain status on the connection, you can view the signal strength on the General tab and the IP address configuration on the Support tab. If the wireless adapter has an Automatic Private IP Addressing (APIPA) address (169.254.0.0/16) or the configured alternate IP address, then authentication has failed and the Windows XP wireless client is still associated with the wireless AP. If the authentication fails and the association is still in place, the wireless adapter is enabled and TCP/IP performs its normal configuration process. If a DHCP server is not found, it automatically configures an APIPA or alternate address.

For Windows 2000 Service Pack 4 (SP4) or later or Windows 2000 Service Pack 3 (SP3) with Microsoft 802.1X Authentication Client, use the Ipconfig tool to display the adapter status and IP address configuration for the wireless network adapter.

Tracing

To obtain detailed information about the Wireless Zero Configuration service for Windows XP SP2 and the EAP authentication process for all versions of Windows XP, you must enable tracing by typing netsh ras set tracing * enabled at a command prompt.

To obtain detailed information about how the Wireless Zero Configuration service connected to a wireless network for computers running Windows XP with SP2, try the wireless connection again and view the Wzcdlg.log and Wzctrace.log files in the SystemRootTracing folder.

To obtain detailed information about the EAP authentication process, try the authentication process again and view the Eapol.log and Rastls.log files in the SystemRootTracing folder.

For Windows 2000, you can enable tracing in the same way to view the Rastls.log files in the SystemRootTracing folder.

To disable tracing, type netsh ras set tracing * disabled at a command prompt.