Cisco WS-C1924-EN-DC - 100Mbps Ethernet Switch Instrukcja Użytkownika Pobierz pdf (Strona 27)

Overview 1-27

Simple Network Management Protocol

Remote Monitoring

The Remote Monitoring (RMON) MIB is used by network managers to monitor remote

devices. An RMON implementation consists of a software probe that continually collects

statistics about a LAN and a management station that communicates with the probe. The

probe transfers information to the management station on request or when a predeﬁned

threshold is crossed. You can use the statistics to help tune or troubleshoot your switched

LAN.

RMON is enabled by default on the switches and is not displayed on the Catalyst 1900

Switch Manager or management console. The switch supports four RMON groups

(Table 1-13) as deﬁned in RFC 1757. You can obtain information about the four supported

groups by using any SNMP management application.

Table 1-13 RMON Groups and Their Functions

Group Name Description

Statistics This group collects utilization and error statistics for the monitored switch. Statistics include

information about collisions, cyclic redundancy checks (CRCs) and alignment; undersized or

oversized packets, jabber, fragments, broadcast, multicast, and unicast messages; and bandwidth

utilization. For example, you could use this group to determine how many error packets have

been seen on a given port.

Statistics from this group can be used by the history group to record historical views of network

performance. A statistics row is established by default for each switch port.

History This group takes periodic samples from the statistics section and stores them for later retrieval.

This sampling includes information such as utilization, error counts, and packet counts. This

information can be used to establish baseline information regarding network activity. You can

deﬁne the intervals you want to record information for, and you can deﬁne how many of the

samples are to be stored.

Note RMON statistics gathering has a maximum limit of 540 history tables that can be allocated

among all switch ports.

Alarm This group generates alarms according to user-deﬁned thresholds. You could, for example,

conﬁgure RMON to generate an alarm when alignment errors on a port exceeded a predeﬁned

limit. Rising and falling thresholds can be deﬁned, and the events group can generate traps and

automated responses based on the alarms.

Event This group sends traps (events) to the management station based on information (alarms)

received from the alarm group. The time and date are recorded with each logged event. You can

use the events group to create customized reports that are based on alarm types.

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Cisco WS-C1924-EN-DC - 100Mbps Ethernet Switch Instrukcja Użytkownika Strona 27