Port Mirror; Loopback Detection Settings - D-Link xStack Reference Manual

xStack® DES-3200 Series Layer 2 Ethernet Managed Switch WEB UI Reference Guide

Port Mirror

The Switch allows you to copy frames transmitted and received on a port and redirect the copies to another port. You
can attach a monitoring device to the mirrored port, such as a sniffer or an RMON probe, to view details about the
packets passing through the first port. This is useful for network monitoring and troubleshooting purposes.
To view this window, click Layer 2 Features > Port Mirror:
To configure a mirror port:
1. Change the status to Enabled.
2. Select the Target Port, which receives the copies from the source port.
3. Select the Source Port from where the frames come from.
4. Click Apply to let the changes take effect.
NOTE: You cannot mirror a fast port onto a slower port. For example, if you try to mirror the
traffic from a 100 Mbps port onto a 10 Mbps port, this can cause throughput problems. The port
you are copying frames from should always support an equal or lower speed than the port to
which you are sending the copies. Also, the target port for the mirroring cannot be a member of
a trunk group. Please note a target port and a source port cannot be the same port.

Loopback Detection Settings

The Loopback Detection function is used to detect the loop created by a specific port. Choose the loopback detection
operation mode. Two modes are supported, port based and VLAN based. In the port-based mode, the port will be
shut-down (be disabled) when a loop is detected; in VLAN-based mode, the port cannot process packets on the VLAN
on which the loop is detected. The default mode is port-based. The Loopback Detection port or VLAN will restart (be
able to forwarding) when the Loopback Detection Recover Time times out. The Loopback Detection function can be
implemented on a range of ports at a time. The user may enable or disable this function using the pull-down menu.
Figure 3 - 40. Port Mirror window
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