Interface monitoring features
You can designate monitoring of inbound and outbound traffic on:
Ports and static trunks:
Allows monitoring of individual ports, groups of contiguous ports, and static port trunks.
The switch monitors network activity by copying all traffic inbound and outbound on the specified interfaces to the
designated monitoring port, to which a network analyzer can be attached.
If a tagged packet arrives on a monitored port, the packet will remain tagged when it goes out a monitored port
even if that port is configured as untagged. If the packet is untagged, it will remain untagged going out the monitor
port. The monitor port state (tagged or untagged) does not affect the tagging of the packet. However, egress
mirroring does not reflect the tagged or untagged characteristic to the mirror port, instead it reflects the tagged or
untagged characteristic of the mirror port.
NOTE:
When both inbound and outbound monitoring is done, and IGMP is enabled on any VLAN,
you may get two copies of IGMP packets on the monitored port.
Port trunks cannot be used as a monitoring port.
The switch can monitor static LACP trunks, but not dynamic LACP trunks.
It is possible, when monitoring multiple interfaces in networks with high traffic levels, to copy more
traffic to a monitor port than the link can support. In this case, some packets may not be copied to
the monitor port.
Configuring port and static trunk monitoring (CLI)
You must use the following configuration sequence to configure port and static trunk monitoring in the CLI:
1.
Assign a monitoring (mirror) port.
2.
Designate the port(s) and/or static trunk(s) to monitor.
Displaying the monitoring configuration
Syntax:
show monitor
This command lists the port assigned to receive monitored traffic and the ports and/or trunks being monitored.
For example, if you assign port 5 as the monitoring port and configure the switch to monitor ports 2-4,
show
monitor
displays the following:
Monitored port listing
switch(config)# show monitor
Network Monitoring Port
Mirror Port: 5
1
Monitoring sources
2
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Chapter 12 Monitoring and Analyzing Switch Operation
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