402 Monitoring Switch Traffic• When a sample is taken, the counter indicating how many packets to skipbefore taking the next sample is reset. The value of the counter is set to arandom integer where the sequence of random integers used over time isthe Sampling Rate.Counter SamplingThe primary objective of Counter Sampling is to efficiently, periodicallyexport counters associated with Data Sources. A maximum Sampling Intervalis assigned to each sFlow instance associated with a Data Source.Counter Sampling is accomplished as follows:• sFlow Agents keep a list of counter sources being sampled.• When a Packet Flow Sample is generated the sFlow Agent examines thelist and adds counters to the sample datagram, least recently sampled first.Counters are only added to the datagram if the sources are within a shortperiod, 5 seconds say, of failing to meet the required Sampling Interval.• Periodically, say every second, the sFlow Agent examines the list of countersources and sends any counters that must be sent to meet the samplinginterval requirement.The set of counters is a fixed set.What is RMON?Like sFlow, RMON is a technology that enables the collection and analysis ofa variety of data about network traffic. PowerConnectM6220/M6348/M8024/M8024-k switch software includes an RMON probe(also known as an RMON agent) that collect information and analyzepackets. The data that is collected is defined in the RMON MIB, RFC 2819.RMON is defined in an Internet Engineering Task Force (IETF) specificationand is an extension of the SNMP MIB. You can view the RMON informationlocally on the switch or by using a generic RMON console on a networkmanagement station (NMS). SNMP does not need to be configured on theswitch to view the RMON data locally. However, if you use a managementstation to view the RMON data that the switch collects and analyzes, youmust configure the following SNMP settings:• Set up the SNMP community string to be used by the SNMP manager at agiven IP address.
