Proxim AP-2000 Benutzerhandbuch

Seite von 244
44
Performing Advanced Configuration
RTS/CTS Medium Reservation: This parameter affects message flow control and should not be changed under 
normal circumstances. Range is 0 to 2347. When set to a value between 0 and 2347, the Access Point uses the 
RTS/CTS mechanism for packets that are the specified size or greater. When set to 2347 (the default setting), 
RTS/CTS is disabled. See 
 for more information.
Closed System: Check this box to allow only clients configured with the Access Point’s specific Network Name to 
associate with the Access Point. When enabled, a client configured with the Network Name “ANY” cannot connect 
to the AP. This option is disabled by default. Se
 for more information.
Wireless Service Status: Select shutdown to shutdown the wireless service on a wireless interface, or resume 
to resume wireless service. See 
 for more information.
Dynamic Frequency Selection (DFS)
802.11a APs sold in Europe use a technique called Dynamic Frequency Selection (DFS) to automatically select an 
operating channel. During boot-up, the AP scans the available frequency and selects a channel that is free of 
interference. If the AP subsequently detects interference on its channel, it automatically reboots and selects another 
channel that is free of interference.
DFS only applies to 802.11a APs used in Europe (i.e., units whose regulatory domain is set to ETSI). The European 
Telecommunications Standard Institute (ETSI) requires that 802.11a devices use DFS to prevent interference with 
radar systems and other devices that already occupy the 5 GHz band.
If you are using an 802.11a AP in Europe, keep in mind the following:
DFS is not a configurable parameter. It is always enabled and cannot be disabled.
You cannot manually select the device’s operating channel; you must let DFS select the channel.
You cannot configure the Auto Channel Select option. Within the HTTP interface, this option always appears 
enabled.
RTS/CTS Medium Reservation
The 802.11 standard supports optional RTS/CTS communication based on packet size. Without RTS/CTS, a sending 
radio listens to see if another radio is already using the medium before transmitting a data packet. If the medium is 
free, the sending radio transmits its packet. However, there is no guarantee that another radio is not transmitting a 
packet at the same time, causing a collision. This typically occurs when there are hidden nodes (clients that can 
communicate with the Access Point but are out of range of each other) in very large cells.
When RTS/CTS occurs, the sending radio first transmits a Request to Send (RTS) packet to confirm that the medium 
is clear. When the receiving radio successfully receives the RTS packet, it transmits back a Clear to Send (CTS) 
packet to the sending radio. When the sending radio receives the CTS packet, it sends the data packet to the receiving 
radio. The RTS and CTS packets contain a reservation time to notify other radios (including hidden nodes) that the 
medium is in use for a specified period. This helps to minimize collisions. While RTS/CTS adds overhead to the radio 
network, it is particularly useful for large packets that take longer to resend after a collision occurs.
RTS/CTS Medium Reservation is an advanced parameter and supports a range between 0 and 2347 bytes. When set 
to 2347 (the default setting), the RTS/CTS mechanism is disabled. When set to 0, the RTS/CTS mechanism is used 
for all packets. When set to a value between 0 and 2347, the Access Point uses the RTS/CTS mechanism for packets 
that are the specified size or greater. You should not need to enable this parameter for most networks unless you 
suspect that the wireless cell contains hidden nodes.
Wireless Service Status
The user can shutdown (or resume) the wireless service on the wireless interface of the AP through the CLI, HTTP, or 
SNMP interface. When the wireless service on a wireless interface is shutdown, the AP will:
Stop the AP services to wireless clients connected on that wireless interface by disassociating them
Disable the associated BSS ports on that interface
Disable the transmission and reception of frames on that interface
Indicate the wireless service shutdown status of the wireless interface through LED and traps
Enable Ethernet interface so that it can receive a wireless service resume command through CLI/HTTP/SNMP 
interface
NOTE
WSS disables only BSS ports; WDS ports are still operational.