User's Manual

SPEEDLAN 9000 Series Installation and Operation User Guide Version 3.03
Using the Configurator to Set Up Special Parameters for a Base Station 4-7
Star Timing Parameters Section
The timing parameters control how a base station treats CPE routers during time
periods when they have no network traffic to send.
The different polling parameters relate to aging inactive nodes (or sites) off the active
list so a base station does not have to continuously poll them, thereby slowing down
other sites that are more active. If a base station has to poll a router which continuously
responds with "No, I don't have any traffic to send," bandwidth potential is lost since
other routers with traffic to send must wait. On the other hand, if a router is rarely
polled, or even removed from the polling table, it will encounter an additional delay the
next time it has data to transmit. The trade-off is one of latency versus throughput. If
you make the latency too high, users may complain about the delay they will encounter
when they send traffic after a period of inactivity. Conversely, if you make the latency
too low, total network throughput decreases. Although each router has fixed
parameters for each of the three polling stages already set when it leaves Wave
Wireless, the end user is allowed to configure them to fit their own requirements and
applications.
Note: All values are in seconds. The minimum is 0.1 seconds and the maximum is
1,000 seconds (or 1ms).
• Idle Time: The consecutive amount of time since a CPE has transmitted traffic
when it was polled. There are 3 categories (listed below).
• Idle Category 1: The default time is 2 seconds.
• Idle Category 2: The default time is 5 seconds.
• Idle Category 3: The default time is 30 seconds.
• Idle Penalty: How long, at a maximum, a CPE in the corresponding category
(Idle Category 1, 2 or 3) has to wait until it gets polled. At a minimum it takes
2ms to poll a CPE. For example, if it takes 2ms to poll a CPE, multiply the
number of CPE routers (e.g., 8 routers) by 2 (e.g., 8 x 2 = 16). Then, divide 1
second (1,000ms) by this quantity (e.g., 16) to get the maximum number of
times a CPE router can be polled per second (e.g.,1,000 divided by 16 = 62).
(In this example, the calculation really comes to 62.5 but you cannot poll in
half seconds, only full seconds so it’s rounded down.)
• Penalty 1: The default penalty time is 0.25 seconds.
• Penalty 2: The default penalty time is 1 second.
• Penalty 3: The default penalty time is 2 seconds.