RMON is a method of collecting and analysing information from remote network elements (NES).

RMON provides the information to determine where to place the boundaries between collision and broadcast domains, functions provided by LAN switches and routes.

RMON agent attached to a local network element captures information and statistics on protocols and traffic activity communicates the information back to a central RMON management console for processing.

RMON is especially critical when managing a switched Lan environment because LAN segments which previously served many users are now micro segmented. This micro segmentation creates more segments to manage closer to the user.

RMON LAN troubleshooting can be performed proactively with the engineer using RMON agents to look for things that are abnormal based on the threshold criteria.

RMON probes can provide a great deal of information on performance of your LAN and WAN, capturing protocol traffic patterns that enable trending of protocol performance.

RMON can catch utilisation patterns that are exceeding thresholds and alerts the engineer to take action.

All of these monitoring can be done remotely and thus eliminates the need for on side LAN managers to watch the LAN performance.

Figure shows a network where remote SNMP devices are monitored through an SNMP management platform.

An RMON probe is also placed on Ethernet LAN. RMON groups operate at the MAC layer while newer RMON groups operate at the network layer and above.

RFC 1757 defines 10 RMON groups where each collects information on variables and sends it back to central management station for analysis.

Statistics: Maintains error and Utilisation statistics for the specific LAN segments being monitored by RMON agent. E.g.: CRC/alignment, multicast, broadcast.

History: Obtains statistical samples such as packet count, error count and utilisation and sore them for lateral retrieval.

Alarm: Administration control of sampling interval and threshold for any variable monitored by RMON agent. E.g.: absolute or relative values, rising/falling thresholds.

Host: Host traffic measurements such as packets or bytes sent and received, errors etc.

Host Top N: Reporting on Top N Host statistics.

Traffic Matrix: Stores errors and statistics between source and destination nodes on a network.

Filter: Provides a filter engine for packet recognition.

Event: Time and data stamped logging and printing of events.

Packet Capture: Buffering criteria for packets that match filter criteria.

Token Ring: Configuration and statistical information on source routing and statistics on a ring.

RMON 2 provides new groups that operate at the network layer and higher. These group include,

Network Layer and Application Layer Host: Statistics for each network address and each application layer protocol on the segment of ring, such as packets and bytes received for Layer 3 traffic an port number of an application respectively.

Network Layer and Application Layer Matrix: Traffic statistics at the network and application layer protocols between source and destination nodes on a network.

Protocol Directory: User-selectable protocols that are monitored and counted.

Protocol distribution: Table of statistics for each protocol in directory.

User defined History: Sampling of any MIB object monitored by the RMON agent.

Address Mapping: Listing of MAC to network-layer address binding such as with ARP.

Configuration groups: Listing of RMON agent configurations and capabilities.

Today the application of remote monitoring and control extends from fields such as:

• Smart grid
• Structural health monitoring
• Pipeline sensors
• Patient monitoring
• Desktop/server monitoring