WESM zl Management and Configuration Guide WT.01.XX and greater

4-65
Wireless Local Area Networks (WLANs)
Configuring a WLAN
Remember that this setting applies to a WLAN; it does not apply to an RP as
a whole, which might associate with stations in several WLANs. If you want
to prevent the Wireless Edge Services zl Module from forwarding traffic
between wireless stations in different WLANs, you must configure this option
for both WLANs.
Note Remember to consider whether a RPs must forward traffic between devices
such as Voice-over-WLAN (VoWLAN) phones.
Enabling Closed System Operations
Wireless stations have two ways that they can discover the SSID for a WLAN:
■ RPs send beacons that include the SSID for the WLAN. All wireless
stations listen for beacons.
■ RPs answer probes from stations requesting the RP to send all SSIDs that
it supports.
RPs can only beacon the SSIDs for the four primary WLANs (with normal
configuration, WLANs 1 through 4). This second option allows some
wireless stations to automatically discover the SSID for the other WLANs
as well.
To configure a WLAN to operate truly in closed system—that is prevent
wireless stations from discovering the WLAN’s SSID—you must disable both
of the functions described above.
In the past, organizations have used closed system as a rudimentary security
measure. However, widely available wireless sniffer software can detect
SSIDs in management frames with already associated stations. Therefore,
closed system deters only the most casual of unauthorized users. For true
security, enable authentication and encryption as described in “Configuring
Security Options” on page 4-33.
To configure a WLAN to operate in closed system, complete these steps:
1. Access the Edit screen for the WLAN:
a. Select Network Setup > WLAN Setup and click the Configuration tab.
b. Select the WLAN and click the Edit button. The Edit screen is displayed.