System information

422 Observer Suite: RMON Console
Note: The RMON standard does not consider an event to happen unless
both Upper and Lower Thresholds have been crossed.
Collisions
Collisions show the best estimate of the number of collisions on this Ethernet segment.
The value returned will depend 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 could record more
collisions than a Probe connected to a station on the same segment would.
Probe location plays a much smaller role when considering 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 only detect collisions when it is transmitting. Thus, Probes placed
on a station and a repeater, should report the same number of collisions.
Note: An RMON Probe inside a repeater should 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.
CRC & Alignment Errors
The number of packets received that had a length (excluding framing bits, but including
FCS octets) of between 64 and 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 non-
integral number of octets (Alignment Error).
Fragments
The number of packets received 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
30% 37500000
40% 50000000
50% 62500000
60% 75000000
70% 87500000
80% 100000000
90% 112500000
100% 125000000