National Instruments NI WAP-3711 - Manual (Page 41)

NI WAP-3701/3711 User’s Manual Troubleshooting
B-2
TCP/IP Settings Problems
Default Gateway
of Client Computer
AP
IEEE 802.11g
Stage A State B
Correspondent
Host
Stage D
Client
Computer
DNS Server
of Client Computer
Ethernet LAN
Internet
Communication stages for a client to reach its correspondent host
For a wireless client computer to communicate with a 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, and 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 reverse path. When the client computer receives the DNS reply, it knows the IP
address of the correspondent host and sends additional packets to this IP address.
As illustrated in the above figure, the communication path could be broken at some of the stages.
The OS-provided network diagnostic tool, ping.exe, can be employed to determine TCP/IP-related
communication 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:
The AP does not respond to ping from the client computer.
y Are two or more NICs installed on the client computer?
¾ Use the OS-provided command-line network tool, route.exe, to modify the contents of
the routing table.
¾ Use Windows-provided Device Manager to disable unnecessary NICs.
y Is the underlying link (Ethernet or IEEE 802.11g) established?
¾ Make sure the Ethernet link is OK.