Operating Modes - Motorola AP-7131 Product Reference Manual

1-24 AP-7131 Access Point Product Reference Guide
MUs perform partial scans at programmed intervals, when missing expected beacons or after
excessive transmission retries. In a partial scan, the MU scans access points classified as proximate
on the access point table. For each channel, the MU tests for Clear Channel Assessment (CCA). The
MU broadcasts a probe with the ESSID and broadcast BSS_ID when the channel is transmission-free.
It sends an ACK to a directed probe response from the access point and updates the table.
An MU can roam within a coverage area by switching access points. Roaming occurs when:
• Unassociated MU attempts to associate or reassociate with an available access point
• Supported rate changes or the MU finds a better transmit rate with another access point
• RSSI (received signal strength indicator) of a potential access point exceeds the current
access point
• Ratio of good-transmitted packets to attempted-transmitted packets that fall below a
threshold.
An MU selects the best available access point and adjusts itself to the access point direct-sequence
channel to begin association. Once associated, the access point begins forwarding frames addressed
to the target MU. Each frame contains fields for the current direct-sequence channel. The MU uses
these fields to resynchronize to the access point.
The scanning and association process continues for active MUs. This process allows MUs to find new
access points and discard out-of-range or deactivated access points. By testing the airwaves, MUs
can choose the best network connection available.

1.2.6 Operating Modes

The access point can operate in a couple of configurations.
• Access Point - As an Access Point, the access point functions as a layer 2 bridge. The wired
uplink can operate as a trunk and support multiple VLANs. Up to 16 WLANs can be defined
and mapped to access point WLANs. Each WLAN can be configured to be broadcast by one
or both access point radios. An AP-7131 can operate in both an Access Point mode and
Wireless Gateway/Router mode simultaneously. The network architecture and access point
configuration define how the Access Point and Wireless Gateway/Router mode are
negotiated.
• Wireless Gateway/Router - If operating as a Wireless Gateway/Router, the access point
functions as a router between two layer 2 networks: the WAN uplink (the ethernet port) and
the Wireless side. The following options are available providing a solution for single-cell
deployment: