RMON Supported by the Device
Before configuring RMON, understand concepts of four groups (statistics, history, alarm, and event) and Huawei-defined extended alarm group.
RMON
RMON provides packet statistics and alarm functions. The management devices use RMON to remotely monitor and manage network elements.
RMON uses statistics group and history group to provide Ethernet statistics and history statistics functions.
- Ethernet statistics (statistics group in RMON MIB): collects basic statistics on each monitored network. The system keeps on collecting traffic statistics and distribution of each type of packets on a network segment. Additionally, the system can count the number of error packets of different types, collisions, CRC error packets, undersized (or large) packets, broadcast and multicast packets, bytes received, and packets received.
- History statistics (history group in RMON MIB): periodically samples and records network statistics. The system can periodically collect statistics on each type of traffic, including bandwidth usage, number of error packets, and total number of packets.
RMON alarm functions include event definition function and alarm threshold setting function.
Event definition (event group in RMON MIB): controls the events and notifications sent from the device and provides all events related to RMON agent. When an event occurs, the system records a log or sends a trap to the NMS.
Alarm threshold setting (alarm group in RMON MIB): monitors the specified alarm variables (OID of an object). Based on the user-defined thresholds and sampling time, the system periodically obtains the specified alarm variables. When the alarm variables values reach or exceed the rising threshold, a rising threshold alarm event is triggered. When the alarm variables values reach or fall below the falling threshold, a falling threshold alarm event is triggered. The RMON agent records the monitored status in log or sends a trap to the NMS.
RMON standard (RFC 2819) defines multiple RMON groups. The switch supports the Huawei-defined extended alarm, statistics, history, alarm, and event groups. Details about the groups are as follows:
Statistics group
The statistics group keeps on collecting statistics on each type of traffic on Ethernet interfaces and records statistics results in the etherStatsTable for later retrieval. Traffic statistics include the number of network collisions, CRC error packets, undersized (or large) data packets, broadcast packets, multicast packets, received bytes, and received packets.
After a statistics entry is created on an interface, the statistics group starts collecting statistics on the packets. The statistics are accumulated.
History group
The history group periodically collects network status statistics and stores them for future use.
The history group provides two tables:
historyControlTable: sets control information such as the sampling interval.
etherHistoryTable: stores network statistics collected by the history group and provides the network administrator with history statistics such as the traffic on a network segment, error packets, broadcast packets, bandwidth usage, and collisions.
Event group
The defined events are used for the configuration options of alarm group and extended alarm group. When alarm conditions are met, an event is triggered. RMON event management is to add events to the specified rows in the event table, and the following options are supported:
log: only send log
trap: only send trap to the NMS
log-trap: send both log and trap
none: take no action
Alarm group
An alarm group presets a set of thresholds for alarm variables, which can be objects in a local MIB. Based on the user-defined alarmTable, the system periodically obtains the specified alarm variables. When the alarm variables values reach or exceed the rising threshold, a rising threshold alarm event is triggered. When the alarm variables values reach or fall below the falling threshold, the system takes actions according to the action configuration.
Extended alarm group
Based on RFC 2819, the extended alarm group has the following new function: set alarm object and keepalive time using expressions. This group provides the prialarmTable. Compared with the alarm table defined in RFC 2819, the extended alarm table has the following new options:
Extended alarm variable expression. It is the arithmetic expression composed of alarm variables OIDs (+, -, *, /, or brackets).
Descriptions of extended alarm entries
Sampling interval variables
Extended alarm types: Forever or Cycle. If Cycle is set, no alarm is generated and the entry is deleted after the specified cycle period expires.
Each entry has a lifetime. When an entry's status is not valid, the entry can exist for a certain period before it is deleted. The entry is deleted when the lifetime decreases to 0. Table 2-1 shows the capacity of each table and the maximum lifetime of an entry in each table.
Table |
Table Size (Bytes) |
Maximum Lifetime (Seconds) |
|---|---|---|
etherStatsTable |
100 |
600 |
historyControlTable |
100 |
600 |
alarmTable |
60 |
6000 |
eventTable |
60 |
600 |
logTable |
600 |
- |
prialarmTable |
50 | 6000 |
Each entry in the historyControlTable corresponds to a maximum of 10 history records in the etherHistoryTable. When more than 10 records are generated, the old ones are overwritten.
No maximum lifetime is specified for the entries in logTable. Each event entry in logTable corresponds to up to 10 logs. When more than 10 logs are generated, the old ones are overwritten.
