Remote Monitoring (RMON) is a standard monitoring specification that enables various network monitors and console systems to exchange network-monitoring data. RMON provides network administrators with more freedom in selecting network-monitoring probes and consoles with features that meet their particular networking needs.
RMON was originally developed to address the problem of managing LAN segments and remote sites from a central location. The RMON is an extension of the SNMP MIB. Within an RMON network, monitoring data is defined by a set of statistics and functions and exchanged between various different monitors and console systems. Resultant data is used to monitor network utilization for network planning and performance-tuning, as well as assisting in network fault diagnosis.
There are 2 versions of RMON: RMONv1 and RMONv2. RMONv1, which can now be found on most modern network hardware, defined 9 MIB groups for basic network monitoring. RMON2 is an extension of RMON that focuses on higher layers of traffic above the medium-access-control(MAC) layer. RMON2 has an emphasis on IP traffic and application-level traffic. RMON2 allows network management applications to monitor packets on all network layers. This is different from RMONv1, which only allows network monitoring at MAC layer or below.
RMON solutions are comprised of two components: a probe (or an agent or a monitor), and a management station. Agents store network information within their RMON MIB and are normally found as embedded software on network hardware such as routers and switches although they can be a program running on a PC. Agents can only see the traffic that flows through them so they must be placed on each LAN segment or WAN link that is to be monitored. Clients, or management stations, communicate with the RMON agent or probe, using SNMP to obtain and correlate RMON data.
There are a number of variations to the RMON MIB. For example, the Token Ring RMON MIB provides objects specific to managing Token Ring networks. The SMON MIB extends RMON by providing RMON analysis for switched networks.
Protocol Structure of RMON
RMON 1 MIB Group
- Statistics Contains statistics measured by the probe for each monitored interface on this device.
- History Records periodic statistical samples from a network and stored for retrieval.
- Alarm Periodically takes statistical samples and compares them with set thresholds for events generation.
- Host Contains statistics associated with each host discovered on the network.
- HostTopN Prepares tables that describe the top hosts.
- Matrix Stores and retrieves statistics for conversations between sets of two addresses.
- Filters Enable packets to be matched by a filter equation for capturing or events.
- Packet Capture Enables packets to be captured after they flow through a channel.
- Events Control the generation and notification of events from this device.
- Token Ring Support of Token Ring
RMON 2 MIB Group
- Protocol Directory The Protocol Directory is a simple and interoperable way for an RMON2 application to establish which protocols a particular RMON2 agent implements. This is especially important when the application and the agent are from different vendors.
- Protocol Distribution Mapping the data collected by a probe to the correct protocol name that can then be displayed to the network manager.
- Address mapping Address translation between MAC-layer addresses and network-layer addresses which are much easier to read and remember. Address translation not only helps the network manager, it supports the SNMP management platform and will lead to improved topology maps.
- Network Layer host Network host (IP layer) statistics
- Network layer matrix Stores and retrieves network layer (IP layer) statistics for conversations between sets of two addresses.
- Application layer host Application host statistic
- Application layer matrix Stores and retrieves application layer statistics for conversations between sets of two addresses.
- User history This feature enables the network manager to configure history studies of any counter in the system, such as a specific history on a particular file server or a router-to-router connection
- Probe configuration This RMON2 feature enables one vendor’s RMON application to remotely configure another vendor’s RMON probe.
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