Port Mirror configuration in Mist UI

 How to configure port mirroring in Mist UI

Please follow below steps:

In the UI go to Switches > List > Click in the switch name > Port Mirroring > Check "Override Site/Template Settings" > Add Port Mirror > Configure a name under "Port Analyzer Name" > Add Inputs > Select Network > Output (select output interface or VLAN) > save > Save.

How to Configure Port Mirroring?

Inputs - This specifies the Input source from which the packet should be received so that it can be mirrored. Minimum of 1 input is mandatory for any port mirror config.

• Input VLAN: Specifying this assumes that the port mirroring takes all the packets entering that particular VLAN will be mirrored to the specified output.
• Input Port: Specifying this assumes that the port mirroring takes all the packets entering or exiting that particular port will be mirrored to the specified output.
  • These are further sub divided to 2 forms:
    • > Ingress: This specify packets entering the particular port will be mirrored.
    • > Egress: This specify packets exiting the particular port will be mirrored.

[ Note that if VLAN is specified we only have option Ingress and only the packets entering the VLAN will be mirrored. Whereas if ports are specified, we can specify Ingress and Egress option. i.e VLAN input is always ingress by default]

Outputs - This specifies the output to which the packet should be mirrored. Exactly 1 output must be configured for any port mirror config.

• Output VLAN: Specifying this will send the mirrored packets to the specified VLAN.
  • [To avoid looping, ie continuous mirroring of packets belonging to same VLAN- Input VLAN if specified must not be same as output VLAN. Currently UI does not allow to create port mirror config with same VLAN as Input and Output.]

• Output Port: Specifying this will send the mirrored packets to the specified port.
  • [To avoid looping, ie continuous mirroring of packets belonging to same port - Input port if specified must not be same as output port. Currently UI does not allow to create port mirror config with same port as Input and Output.]

You can validate the port mirror is configured by checking the switch events or from the CLI.

Validation:

1. Wait for Configured event in Device events. (UI Validation)
2. Go to Remote shell
   1. Go to cli mode: > show configuration | display set | match analyzer

For more information:

Configuring Port Mirroring and Analyzers | Junos OS | Juniper Networks

https://supportportal.juniper.net/s/article/EX-QFX-Local-and-remote-port-mirror-configuration-example

https://supportportal.juniper.net/s/article/Guidelines-for-Port-Mirroring-and-Analyzers-on-EX2300-EX3400-and-EX4300-Switches