Cabletron Systems CSX1000 - Manual (Page 317)

Workgroup Remote Access Switch 317
C ONFIGURING C ALL C ONTROL
Throughput Monitor
I DLE C ONDITION M ONITORING
The CyberSWITCH monitors for the idle condition when only one connection to another site
remains. The system detects when there is no longer a need to maintain connectivity with the other
site. An absolute idle condition is defined as a number of consecutive sample periods with zero
bytes transferred.
Keep-alive type frames may sometimes continue to flow when there is no actual device data
flowing. The system would not detect a completely idle condition, and might leave a connection in
use when it may no longer carry useful traffic. Instead of monitoring for zero traffic, the idle
condition can be set up to detect extremely low, but non-zero, bandwidth utilization. This can be
done by not requiring all samples in the window to be zero, or by monitoring for a low percentage
utilization level.
Background traffic is often transmitted continuously. It may be necessary to have a minimum
dedicated connection to handle the constant traffic, then use switched connections for peak loads
and backup.
T HROUGHPUT M ONITOR C ONFIGURATION E XAMPLE
In the above example, the sample rate is 5 seconds, the number of samples to examine per sample
rate (the window) is 3, the configured percentage to compare against (utilization) is 50 percent, the
number of times the sample’s utilization percentage must be greater than the configured utilization
percentage (the trigger) is 2 out of 3 samples. To make things simpler for this example, there is only
one call up and we are only checking to add another call (overload).
After 5 seconds the sample is checked and the average utilization for the 5 seconds was 40 percent.
This is less than the configured utilization percentage of 50%, so no action is taken. For the second
sample rate period, the average throughput is 60%. This percentage is greater than the configured
utilization percentage, so the trigger must also be checked. At this point, only 2 samples have been
taken, and the configured window is for 3 samples. The overload condition needs to be met 2 times
(the trigger of 2) out of 3 samples (the window of 3) before any action is taken. This condition has
not been met.
Sample rate 5
Window 3
Trigger 2
Utilization 50%
50%
5
10
15
20
25
30
35
0 of 1
1 of 2
1 of 3
1 of 3
1 of 3
2 of 3 Overload condition met
0 of 1
Time
Sliding Window