How to enable port mirroring on a Linksys Smart Gigabit Switch

Port mirroring is used on a network device to send a copy of the network packets seen on one or multiple device ports to a network monitoring connection on another port on the device.  This is commonly used for network appliances that require monitoring of network traffic, such as an intrusion-detection system.  A network analyzer connected to the monitoring port processes the data packets for diagnosing, debugging, and performance monitoring.  
Before you begin, take note of the following:  
  • The Linksys Smart Gigabit Switch (LGS3xxx) and Linksys Managed Switch (LGS5xxx) support port mirroring.
  • Up to four sources can be mirrored.  This can be any combination of four individual ports.
  • A packet that is received on a network port assigned to a VLAN that is subject to mirroring is mirrored to the analyzer port even if the packet was eventually trapped or discarded.  Packets sent by the device are mirrored when Transmit (Tx) mirroring is activated.
  • Mirroring does not guarantee that all traffic from the source port(s) is received on the analyzer (destination) port.  If more data is sent to the analyzer port than it can support, some data might be lost.
  • Only one instance of mirroring is supported throughout the system.  The analyzer port is the same for all the mirrored ports.
Configuring port mirroring on the Linksys Smart Gigabit Switch

Step 1:
Access the switch’s web-based setup page.  For instructions on a Linksys Smart Gigabit Switch, click here.  For a Linksys Managed Switch, click here.
Step 2:
On the setup page, click Maintenance Diagnostics Port Mirroring.

NOTE:  Some of the subtabs may vary slightly depending on the exact model number of your device.
User-added image
The Port Mirroring Table will display the following information:
  • Destination Port – The analyzer port to which traffic is to be copied.  
  • Source Port – The interface port where the traffic to be sent to the analyzer port is from.
  • Mirror Type – Type of monitoring: incoming to the port (Rx), outgoing from the port (Tx) or both.
  • Status – Displays one of the following values:
    • Active – Both source and destination interfaces are up and forwarding traffic.
    • Not Ready – Either the source or destination port (or both) are down or not forwarding traffic for some reason.
Step 3:
Click the Add button to add a port to be mirrored.
Step 4:
Enter these parameters:
  • Destination Port – Select the analyzer port to where packets are to be copied.  A network analyzer, such as a computer running Wireshark, should be connected to this port.  If a port is identified as an analyzer destination port, it remains the analyzer destination port until all entries are removed.
  • Source Port – Select the source port of the traffic to be mirrored.
  • Type – Select whether incoming, outgoing or both types of traffic are mirrored to the analyzer port.  If a port is selected, the options are as follows:
    • Rx Only – Port mirroring on incoming packets.
    • Tx Only – Port mirroring on outgoing packets.
    • Tx & Rx – Port mirroring on both incoming and outgoing packets.
User-added image
Step 5:
Click Apply.  
Port mirroring is now added to the Running Configuration file of the switch.
Related Article:

User Guides for Linksys Switches (Business)

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