| > But he also want ethernet collisions. I'm not aware of any standard MIB
> entry for collisions or am I missing it somewhere ?
The RMON MIB (rfc1757) etherStatsCollisions object counts the total number
of collisions on the Ethernet segment. Trouble is, many product with embedded
RMON don't support this counter right. Many just count the number of
collisions involved with the devices attempts to transmit, rather than the
total number of collisions on the wire.
You're most likely to find this counter supported by dedicated RMON probes.
The DECpacketProbe90 has been ECOs to correctly support this counter, but
from rumors I hear, it hasn't been shipping with the ECO yet.
Other MIBs (Eternet-Like, Repeater) have collision counters which just
report the number of collisions involved in transmits.
> For example, can it be found out for a 2100 OSF/1 V3.0B machine or for
> modules in a DEChub 900 ?
DEChub900: Only with an ECOed PacketProbe90.
2100 OSF/1 V3.0B: Not sure. I'm not aware of any adapter cards which
support this form of collision counter.
-Shawn
------------------------
etherStatsCollisions OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The best estimate of the total 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 also that 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."
::= { etherStatsEntry 13 }
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