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HP 1.10GB Virtual Connect Ethernet Module for c-Class BladeSystem User Manual

Page 168

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Port Statistic

Description

EtherStatsJabbers

The total number of packets received that were longer than 1518 octets

(excluding framing bits, but including FCS octets), and 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). This definition of jabber is
different than the definition in IEEE-802.3 section 8.2.1.5 (10BASE5) and

section 10.3.1.4 (10BASE2). These documents define jabber as the

condition where any packet exceeds 20 ms. The allowed range to detect
jabber is between 20 ms and 150 ms.

EtherStatsOctets

The total number of octets of data (including those in bad packets)

received on the FCS octets). This object can be used as a reasonable

estimate of Ethernet utilization. If greater precision is required, the
StatsPkts and StatsOctets objects should be sampled before and after a

common interval. The differences in the sampled values are Pkts and

Octets, respectively, and the number of seconds in the interval is Interval.
These values are used to calculate the Utilization as follows: Utilization =

[(Pkts * (9.6 + 6.4) + (Octets * .8)) / (Interval * 10,000)]. The result of this

equation is the value Utilization which is the percent utilization of the
Ethernet segment on a scale of 0 to 100 percent.

EtherStatsPkts

The total number of packets (including bad packets, broadcast packets,

and multicast packets) received.

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.