User's Manual

!AcroLAN Card User’s Guide Version 20002.5

Page 7 of 38

observed packet error rates. Once accepted by the access point, the client tunes to the

radio channel to which the access point is set. Periodically it surveys all 802.11 channels

in order to assess whether a different access point would provide it with better

performance characteristics. If it determines that this is the case, it reassociates with the

new access point, tuning to the radio channel to which that access point is set.

Reassociation usually occurs because the wireless station has physically moved away

from the original access point, causing the signal to weaken. In other cases,

Reassociation occurs due to a change in radio characteristics in the building, or due

simply to high network traffic on the original access point. In the latter case this function

is known as “load balancing,” since its primary function is to distribute the total WLAN

load most efficiently across the available wireless infrastructure. This process of

dynamically associating and reassociating with APs allows network managers to set up

WLANs with very broad coverage by creating a series of overlapping 802.11b cells

throughout a building or across a campus. To be successful, the IT manager ideally will

employ “channel reuse,” taking care to set up each access point on an 802.11 DSSS

channel that does not overlap with a channel used by a neighboring access point.

Figure

Roam

ing

Backbone Network

Access Point (AP)

Inter-Cell Roaming