D-Link xStack DGS-3426P User Manual - Port Mirroring

xStack DGS-3400 Series Layer 2 Gigabit Ethernet Managed Switch 

Port Mirroring 

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 the Port Mirroring window, click Port 

Mirroring in the Administration folder. 

Figure 6- 19. Port Mirroring window 

To configure a mirror port: 

1. Select 

theTarget Port on the Unit to which frames will be copied, which receives the copies from the source port. 

2.  Select the Source Direction, Ingress, Egress, or Both and change the Statusdrop-down menu to Enabled. 

3. 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. 

NOTE: Target mirror ports cannot be members of a trunking group. Attempting to do so will 

produce an error message and the configuration will not be set. 

Mirroing within the Switch Stack 

Users may configure mirroring between switches in the switch stack but certain conditions and restrictions apply.  

1.  When mirroing is configured in the stack, the primary master and the backup master will save and synchronize these 

mirroring configurations in their respecitve databases. Therefore, if the primary master is removed, the backup master 

will still hold the mirroing configurations set. 

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