Overview - Allied Telesis AT-8100L/8 User Manual

Chapter 27: Port Mirror

Overview

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The port mirror is a management tool that allows you to monitor the traffic
on one or more ports on the switch. It works by copying the traffic from
designated ports to another port where the traffic can be monitored with a
network analyzer. The port mirror can be used to troubleshoot network
problems or to investigate possible unauthorized network access. The
performance and speed of the switch is not affected by the port mirror.
To use this feature, you must designate one or more source ports and the
destination port. The source ports are the ports whose packets are to be
mirrored and monitored. The destination port is the port where the packets
from the source ports are copied and where the network analyzer is
connected. There can be only one destination port on the switch.
Here are the guidelines for the port mirror:

The switch supports only one port mirror.

The port mirror can have just one destination port.

The port mirror can have more than one source port. This allows
you to monitor the traffic on multiple ports at the same time. For
example, you might monitor the traffic on all the ports of a
particular VLAN.
 You can mirror the ingress traffic, the egress traffic or both on the
source ports.
 The destination port should not be a member of a static port trunk
or an LACP trunk.