Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?


Understanding Port-Mirroring Instances on Different Routers


You can configure port mirroring for IPv4 and IPv6 traffic on all M Series, T Series, and MX Series routers. In addition, on the M7i, M10i, M120, M320, and MX Series routers, you can configure port mirroring for Layer 2 VPLS traffic.

You configure global port mirroring by including the port-mirroring statement at the [edit forwarding-options] hierarchy level. Configuring port-mirroring properties globally results in the properties being applied system-wide to all the Packet Forwarding Engines and their respective ports.

On MX Series, M320, and M120 routers, you can configure named port-mirroring instances for Layer 2 VPLS traffic. Configuring port-mirroring instances enables you to customize each instance with different properties for input-sampling and port-mirroring output destinations, instead of having to use a single system-wide configuration for port mirroring.

You configure multiple port-mirroring instances by including the instance port-mirroring-instance-name statement at the [edit forwarding-options port-mirroring] hierarchy level. You can then associate individual port-mirroring instances with an FPC, PIC, or FEB (depending on the router).


When you configure port-mirroring for the same traffic flow twice, for example, for family Inet and family VPLS, you must configure separate named port-mirror instances for each traffic flow. Inheriting port-mirroring parameters from another instance might result in unexpected behavior.

For more information about configuring port mirroring on all routers, see the Routing Policies, Firewall Filters, and Traffic Policers Feature Guide. For more information on configuring port mirroring for Layer 2 VPLS traffic on MX Series routers, see the Junos OS Layer 2 Configuration Guide.