Cabletron Systems Cabletron CyberSWITCH CSX5500 User Manual

Also see for CyberSWITCH 5500: Quick start Manual

Contents

Central Site Remote Access Switch 369C ONFIGURING C ALL C ONTROLThroughput MonitorU NDERLOAD C ONDITION MONITORINGThe underload condition is monitored by comparing the samples with a lower threshold. Thesample is marked as a true condition if both the transmit and the receive byte count fall below thethreshold. When the number of true samples in the window reaches the configured limit, theunderload condition has occurred.The purpose of detecting this condition is to decide if connections can be released. Therefore, anunderload threshold is defined in terms of a target bandwidth that is less than the current aggregatebandwidth. The underload condition indicates that the target capacity can satisfy the trafficdemand.When only one circuit remains in a group, the underload mechanism determines if a lowerbandwidth circuit would satisfy the demand. For example, if one 384Kbps circuit remained, atarget of 64Kbps could be specified and the above described mechanisms will identify when the64Kbps circuit would satisfy the demand.I DLE C ONDITION M ONITORINGThe CyberSWITCH monitors for the idle condition when only one connection to another siteremains. The system detects when there is no longer a need to maintain connectivity with the othersite. An absolute idle condition is defined as a number of consecutive sample periods with zerobytes transferred.Keep-alive type frames may sometimes continue to flow when there is no actual device dataflowing. The system would not detect a completely idle condition, and might leave a connection inuse when it may no longer carry useful traffic. Instead of monitoring for zero traffic, the idlecondition can be set up to detect extremely low, but non-zero, bandwidth utilization. This can bedone by not requiring all samples in the window to be zero, or by monitoring for a low percentageutilization level.Background traffic is often transmitted continuously. It may be necessary to have a minimumdedicated connection to handle the constant traffic, then use switched connections for peak loadsand backup.THROUGHPUT M ONITOR C ONFIGURATION E XAMPLEIn the following example, the sample rate is 5 seconds, the number of samples to examine persample rate (the window) is 3, the configured percentage to compare against (utilization) is 50percent, the number of times the sample’s utilization percentage must be greater than theconfigured utilization percentage (the trigger) is 2 out of 3 samples. To make things simpler for thisexample, there is only one call up and we are only checking to add another call (overload).