Allied Telesis AT-GS950/48 - Manual (Page 114)

Chapter 8: Port Mirroring
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Overview
The port mirroring feature allows you to unobtrusively monitor the traffic
received and transmitted on one or more ports by copying the traffic to
another switch port. You can connect a data analyzer to the port where the
traffic is copied and monitor the traffic on the other ports without impacting
network performance or speed.
A port mirror has two component ports. The port or ports whose traffic you
want to mirror is called the source port(s). The port where the traffic will be
copied to is called the mirroring port.
Observe the following guidelines when you create a port mirror:
 You can select more than one source port at a time.
However, the more ports you mirror, the less likely the
mirroring port is able to handle all the traffic. For
example, if you mirror the traffic of six heavily active
ports, the destination port is likely to drop packets,
meaning that it does not provide an accurate mirror of
the traffic of the six source ports.
 The source and mirror ports must be located on the
same switch.
 You can mirror the ingress or egress traffic of the
source ports or both.
 While the Mirroring feature is enabled, the mirroring
port is dedicated to monitoring the traffic from the
source ports and cannot used for regular network
operations.