ZyXEL Communications NWA-3550, User Manual

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Chapter 21 Load Balancing
NWA-3160 Series User’s Guide
266
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 NWA 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 NWA has the bandwidth to spare. If too many
people connect and the NWA hits its bandwidth cap then all new connections must
basically wait for their turn or get shunted to the nearest identical AP.
The following figure depicts an NWA with a hard bandwidth limit of 6 Megabits per
second (Mbps). Bandwidth up to 6 Mbps is considered “balanced”. More than that
and it becomes “overloaded”; the AP must then work harder to serve each client.
Figure 160 Load Balancing by Traffic Level Example
The yellow ( Y ), green ( G ) and blue ( B ) laptops are each using approximately 2
Mbps. Altogether, they consume the AP’s entire “balanced” bandwidth allotment.
When the red (
R ) laptop tries to make a connection, the AP (which does not want
to overload itself) denies it if an identical AP is in range that can take on the
burden of the new connection.
Note: If no other APs with matching settings are in range of the NWA, then it will still
accept the connection despite becoming overloaded.
Y
G
B
R