Monitoring Switch Traffic 411
The RMON agent in the switch supports the following groups:
• Group 1—Statistics. Contains cumulative traffic and error statistics.
• Group 2—History. Generates reports from periodic traffic sampling that
are useful for analyzing trends.
• Group 3 —Alarm. Enables the definition and setting of thresholds for
various counters. Thresholds can be passed in either a rising or falling
direction on existing MIB objects, primarily those in the Statistics group.
An alarm is triggered when a threshold is crossed and the alarm is passed to
the Event group. The Alarm requires the Event Group.
• Group 9 —Event. Controls the actions that are taken when an event
occurs. RMON events occur when:
– A threshold (alarm) is exceeded
– There is a match on certain filters.
What is Port Mirroring?
Port mirroring is used to monitor the network traffic that a port sends and
receives. The Port Mirroring feature creates a copy of the traffic that the
source port handles and sends it to a destination port. The source port is the
port that is being monitored. The destination port is where you would
connect a network protocol analyzer to learn more about the traffic that is
handled by the source port. Dell Networking switches support RSPAN
destinations where traffic can be tunneled across the operational network.
A port monitoring session includes one or more source ports that mirror
traffic to a single destination port. Sources can include VLANs, physical
interfaces, port-channels, the internal CPU port, or IP or MAC ACL flows.
Certain sources are not supported; i.e., physical members of a port-channel,
VLANs that contain a LAG member, etc. Destination ports, once configured,
no longer participate in spanning tree, IGMP/MLD snooping, or GVRP; do
not learn MAC addresses (learned MAC addresses are purged); do not
participate in routing (route entries are purged); and do not utilize any static
filter configuration. Configuration of a destination port is restored when the
port is no longer configured as a destination port.
NOTE: The switch supports RMON1.