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RMON 5-23
Both rising and falling thresholds are supported, and
thresholds can be on the absolute value of a vari-
able or its delta value. In addition, alarm thresholds
may be autocalibrated or set manually.
Alarms are used to inform you of a network perfor-
mance problem and they can trigger automated
action responses through the Events group.
Hosts
The Hosts group specifies a table of traffic and
error statistics for each host on a LAN segment or
VLAN. Statistics include packets sent and received,
octets sent and received, as well as broadcasts, mul-
ticasts, and error packets sent.
The group supplies a simple discovery mechanism
listing all hosts that have transmitted. The next
group, Hosts Top N, requires implementation of the
Hosts group.
Hosts Top N
The Hosts Top N group extends the Hosts table by
providing sorted host statistics, such as the top 20
nodes sending packets or an ordered list of all
nodes according to the errors they sent over the last
24 hours.
Matrix
The Matrix group shows the amount of traffic and
number of errors between pairs of devices on a LAN
segment or VLAN. For each pair, the Matrix group
maintains counters of the number of packets,
number of octets, and error packets between the
nodes.
The conversation matrix helps you to examine net-
work statistics in more detail to discover who is talk-
ing to whom or if a particular PC is producing more
errors when communicating with its file server, for
example. Combined with Hosts Top N, this allows
you to view the busiest hosts and their primary con-
versation partners.
Filter
The Filter group provides a mechanism to instruct
the RMON probe to capture packets that match a
specific criterion or condition.
Capture
The Capture group allows you to create capture
buffers on the probe that can be requested and
uploaded to the management workstation for
decoding and presentation.
Events
The Events group provides you with the ability to
create entries in an event log and/or send SNMP
traps to the management workstation. Events can
originate from a crossed threshold on any RMON
variable. In addition to the standard five traps
required by SNMP (link up, link down, warm start,
cold start, and authentication failure), RMON adds
two more: rising threshold and falling threshold.
Effective use of the Events group saves you time;
rather than having to watch real-time graphs for