User's Manual

B-2: TCP/IP Settings Problems

Default Gateway

of Client Computer

IEEE 802.11b

Stage A State B

Correspondent

Host

Stage D

Client

Computer

DNS Server

of Client Computer

Ethernet LAN

Internet

Fig. 60. Communication stages for a client to reach its correspondent host.

For a wireless client computer to communicate with a correspondent host on the Internet by the host’s

domain name (e.g. http://www.wi-fi.com

), it first sends a DNS request to a DNS server on the Internet.

The DNS request travels first to the AP, then the AP relays this request to the default gateway of the

client computer. Finally, this request is forwarded by the gateway to the DNS server on the Internet.

The DNS reply issued by the DNS server is transmitted back to the client computer following a re-

verse path. When the client computer receives the DNS reply, it knows the IP address of the corre-

spondent host and sends further packets to this IP address.

As illustrated in Fig. 60, the communication path could be broken at some of the stages. The

OS-provided network diagnostic tool, ping.exe, can be employed to find out TCP/IP-related commu-

nication problems.

NOTE: If two or more NICs are installed and operating on a client computer, TCP/IP may not work

properly due to incorrect entries in the routing table. Use the OS-provided command-line network

tool, route.exe, to add or delete entries from the routing table. Or, use Windows-provided Device

Manager to disable unnecessary NICs.

Solve the following problems in order:

z The AP does not respond to ping from the client computer.

 Are two or more NICs installed on the client computer?

 Use the OS-provided command-line network tool, route.exe, to modify the contents

of the routing table.

 Use Windows-provided Device Manager to disable unnecessary NICs.

 Is the underlying link (Ethernet or IEEE 802.11g) established?

 Make sure the Ethernet link is OK.