Port Statistic

Description

 

 

 

 

EtherStatsCollisions

The best 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 (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. Therefore, 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. Therefore, probes placed on a station

 

 

and a repeater should report the same number of collisions. Additionally,

 

 

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.

 

 

 

 

EtherStatsCRCAlignErrors

The total 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 FCS with an integral number of octets (FCS Error) or

 

 

a bad FCS with a non-integral number of octets (Alignment Error)

 

 

 

 

TXNoErrors

All packets transmitted without errors, less oversized packets

 

RXNoErrors

All packets received without errors, less oversized and undersized

 

 

packets

 

 

 

 

Dot3StatsAlignmentErrors

A count of frames received on a particular interface that are not an

 

 

integral number of octets in length and do not pass the FCS check. The

 

 

count represented by an instance of this object is incremented when the

 

 

alignmentError status is returned by the MAC service to the LLC (or other

 

 

MAC user). According to the conventions of IEEE 802.3 Layer

 

 

Management, received frames for which multiple error conditions are

 

 

obtained are counted exclusively according to the error status presented

 

 

to the LLC. This counter does not increment for 8-bit wide group encoding

 

 

schemes.

 

 

 

 

Dot3StatsFCSErrors

A count of frames received on a particular interface that are an integral

 

 

number of octets in length but do not pass the FCS check. This count does

 

 

not include frames received with a frame-too-long or frame-too-short error.

 

 

The count represented by an instance of this object is incremented when

 

 

the frameCheckError status is returned by the MAC service to the LLC (or

 

 

other MAC user). According to the conventions of IEEE 802.3 Layer

 

 

Management, received frames for which multiple error conditions are

 

 

obtained are counted exclusively according to the error status presented

 

 

to the LLC. Coding errors detected by the physical layer for speeds above

 

 

10 Mb/s cause the frame to fail the FCS check.

 

 

 

 

Dot3StatsSingleCollisionFrames

A count of successfully transmitted frames on a particular interface for

 

 

which transmission is inhibited by exactly one collision. A frame that is

 

 

counted by an instance of this object is also counted by the corresponding

 

 

instance of either the ifOutUcastPkts, ifOutMulticastPkts, or

 

 

ifOutBroadcastPkts, and is not counted by the corresponding instance of

 

 

the dot3StatsMultipleCollisionFrames object. This counter does not

 

 

increment when the interface is operating in full-duplex mode.

 

 

 

 

 

Virtual Connect modules 253