Chapter 6 Configuring Remote Monitoring (RMON)
Viewing RMON Information
6-30
Cisco Content Services Switch Administration Guide
OL-5647-02
Collisions The best estimate of the total number of collisions on this
Ethernet segment.
The returned value 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 are transmitting simultaneously. A repeater
port must detect a collision when two or more stations are
transmitting simultaneously. Thus, a probe placed on a
repeater port might record more collisions than would a
probe connected to a station on the same segment.
Probe location plays a much smaller role when considering
10BASE-T. IEEE standard 802.3 14.2.1.4, 10BASE-T,
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 collisions
only when it is transmitting. Probes placed on a station and
a repeater should report the same number of collisions.
Ideally, an RMON probe inside a repeater should 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 coaxial segments to
which the repeater is connected.
Packets (0-64)
Packets (65-127)
Packets (128-255)
Packets (256-511)
Packets
(512-1023)
Packets
(1024-1518)
The total number of received packets (including bad
packets) that were between the following octets in length
inclusive (excluding framing bits but including FCS
octets):
• 0 to 64
• 65 to 127
• 128 to 255
• 256 to 511
• 512 to 1023
• 1024 to 1518
Table 6-4 Field Descriptions for the show rmon Command (continued)
Field Description
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