ZyXEL Communications UAG2100, Руководство пользователя

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Chapter 9 Wireless
UAG Series User’s Guide
153
Finally, there is an alternative four channel scheme for ETSI, consisting of channels 1, 5, 9, 13. This
offers significantly less overlap that the other one.
Figure 109
An Alternative Four-Channel Deployment
9.8.2 Load Balancing
Because there is a hard upper limit on an AP’s wireless bandwidth, load balancing can be crucial in
areas crowded with wireless users. Rather than let every user connect and subsequently dilute the
available bandwidth to the point where each connecting device receives a meager trickle, the load
balanced AP instead limits the incoming connections as a means to maintain bandwidth integrity.
There are two kinds of wireless load balancing available on the UAG:
Load balancing by station number limits the number of devices allowed to connect to your AP. If
you know exactly how many stations you want to let connect, choose this option.
For example, if your company’s graphic design team has their own AP and they have 10 computers,
you can load balance for 10. Later, if someone from the sales department visits the graphic design
team’s offices for a meeting and he tries to access the network, his computer’s connection is
delayed, giving it the opportunity to connect to a different, neighboring AP. If he still connects to
the AP regardless of the delay, then the AP may boot other people who are already connected in
order to associate with the new connection.
Load balancing by traffic level limits the number of connections to the AP based on maximum
bandwidth available. If you are uncertain as to the exact number of wireless connections you will
have then choose this option. By setting a maximum bandwidth cap, you allow any number of
devices to connect as long as their total bandwidth usage does not exceed the configured
bandwidth cap associated with this setting. Once the cap is hit, any new connections are rejected or
delayed provided that there are other APs in range.
Imagine a coffee shop in a crowded business district that offers free wireless connectivity to its
customers. The coffee shop owner can’t possibly know how many connections his AP will have at
any given moment. As such, he decides to put a limit on the bandwidth that is available to his
customers but not on the actual number of connections he allows. This means anyone can connect
to his wireless network as long as the AP has the bandwidth to spare. If too many people connect
and the AP hits its bandwidth cap then all new connections must basically wait for their turn or get
shunted to the nearest identical AP.