Viewing RMON1 History Statistics

View RMON1 history statistics when you want to see a statistical sample from the switch. You can create a graph of the statistics in a bar, pie, chart, or line format.

Procedure

  1. In the Device Physical View, select a port.
  2. In the navigation pane, expand the Configuration > Graph folders.
  3. Click Port.
  4. Click the RMON History tab.
  5. Select the statistics you want to graph.
  6. Click the button for the type of graph you require (bar, pie, chart, or line).

RMON History Field Descriptions

Use the data in the following table to use the RMON History tab.

Table 1. Variable definitions

Parameter

Description

SampleIndex

Identifies the particular sample this entry represents among all samples associated with the same history control entry. This index starts at one and increases by one as each new sample is taken.

Utilization

Specifies the best estimate of the mean physical layer network utilization on this interface during the sampling interval, in hundredths of a percent.

Octets

Specifies the total number of octets of data (including those in bad packets) received on the network (excluding framing bits but including FCS octets)

Pkts

Specifies the number of packets (including bad packets) received during this sampling interval.

BroadcastPkts

Specifies the number of good packets received during this sampling interval that were directed to the broadcast address.

MulticastPkts

Specifies the number of good packets received during this sampling interval that the system directs to a multicast address. This number does not include packets addressed to the broadcast address.

DropEvents

Specifies the total number of events in which the probe dropped packets due to lack of resources during this sampling interval. This number is not necessarily the number of packets dropped; it is only the number of times the system detects this condition.

CRCAlignErrors

The number of packets the system receives during this sampling interval that had a length (excluding framing bits but including FCS octets) from 64–1518 octets, inclusive, but had either a bad Frame Check Sequence (FCS) with an integral number of octets (FCS Error) or a bad FCS with a nonintegral number of octets (Alignment Error).

UndersizePkts

Specifies the number of packets the system receives during this sampling interval that were less than 64 octets (excluding framing bits but including FCS octets), and were otherwise well formed.

OversizePkts

Specifies the number of packets the system receives during this sampling interval that were longer than 1518 octets (excluding framing bits but including FCS octets), but were otherwise well formed.

Fragments

Specifies the total number of packets received during this sampling interval that were less than 64 octets in length (excluding framing bits but including FCS octets) and had either a bad Frame Check Sequence (FCS) with an integral number of octets (FCS Error) or a bad FCS with a nonintegral number of octets (Alignment Error).

It is entirely normal for Fragments to increment because it counts both runts (which are normal occurrences due to collisions) and noise hits.

Collisions

Specifies the best estimate of the total number of collisions on this Ethernet segment during this sampling interval. The value returned depends on the location of the RMON probe. Section 8.2.1.3 (10BASE-5) and section 10.3.1.3 (10BASE-2) of IEEE standard 802.3 states that a station must detect a collision in the receive mode if three or more stations transmit simultaneously. A repeater port must detect a collision when two or more stations transmit simultaneously. Thus, a probe placed on a repeater port can record more collisions than a probe connected to a station on the same segment.

Probe location plays a small role when 10BASE-T. 14.2.1.4 (10BASE-T) of IEEE standard 802.3 defines a collision as the simultaneous presence of signals on the DO and RD circuits (transmitting and receiving at the same time). A 10BASE-T station can detect only collisions when it transmits. Thus, probes placed on a station and a repeater can report the same number of collisions.

An RMON probe inside a repeater can ideally report collisions between the repeater and one or more other hosts (transmit collisions as defined by IEEE 802.3k) plus receiver collisions observed on any coax segments to which the repeater is connected.
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