22-30
Cisco ONS 15454 Procedure Guide, R5.0
October 2005
Chapter 22 DLPs A500 to A599
DLP-A533 Create Ethernet RMON Alarm Thresholds
dot3StatsExcessiveCollisions (Not supported by E-Series or G-Series.) Number of frames
where transmissions failed because of excessive collisions
dot3StatsCarrierSenseErrors (G-Series only.) The number of transmission errors on a
particular interface that are not otherwise counted
dot3StatsSQETestErrors (G-Series only.) A count of times that the SQE TEST ERROR
message is generated by the Physical Layer Switch (PLS)
sublayer for a particular interface
etherStatsBroadcastPkts The total number of good packets received that were directed to
the broadcast address; this does not include multicast packets
etherStatsCollisions An estimate of the total number of collisions on this Ethernet
segment. The value returned depends on the location of the
RMON probe. Section 8.2.1.3 (10Base5) and Section 10.3.1.3
(10Base2) of the IEEE 802.3 standard state 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.
Probe location plays a much smaller role when considering
10BaseT. Section 14.2.1.4 (10BaseT) of the IEEE 802.3 standard
defines a collision as the simultaneous presence of signals on the
DO and RD circuits (transmitting and receiving at the same
time). A 10BaseT 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.
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.
Table 22-5 Ethernet Threshold Variables (MIBs) (continued)
Variable Definition
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