Related Documentation
Layer 2 Port Mirroring Overview
On routing platforms and switches that contain an Internet Processor II ASIC, you can send a copy of any incoming packet from the routing platform or switch to an external host address or a packet analyzer for analysis. This is known as port mirroring. In Junos OS Release 9.3 and later, Juniper Networks MX Series 3D Universal Edge Routers in a Layer 2 environment support port mirroring for Layer 2 bridging traffic and virtual private LAN service (VPLS) traffic. In Junos OS Release 9.4 and later, MX Series routers in a Layer 2 environment also support port mirroring for Layer 2 VPN traffic over a circuit cross-connect (CCC) that transparently connects logical interfaces of the same type. In Junos OS Release 12.3R2, Juniper Networks EX Series switches support port mirroring for Layer 2 bridging traffic.
Layer 2 port mirroring enables you to specify the manner in which incoming and outgoing packets at specified ports are monitored and the manner in which copies of selected packets are forwarded to another destination, where the packets can be analyzed. MX Series routers and EX Series switches support Layer 2 port mirroring by performing flow monitoring functions using a class-of-service (CoS) architecture that is in concept similar to, but in particulars different from, other routing platforms and switches.
Like the M120 Multiservice Edge Router and M320 Multiservice Edge Routers, MX Series routers and EX Series switches support port mirroring of IPv4, IPv6, and VPLS packets simultaneously. However, the Junos OS Layer 2 Switching and Bridging Library for Routing Devices describes port mirroring only for Layer 2 bridging traffic (family ethernet-switching), Layer 2 VPLS traffic (family vpls) through an MX Series router, and Layer 2 VPN traffic that passes through a CCC (family ccc).
For general information about packet flow within MX Series routers and other routers, see the Junos OS Class of Service Library for Routing Devices.
In a Layer 3 environment, MX Series routers and EX Series switches support port mirroring of IPv4 (family inet) and IPv6 (family inet6) traffic. For information about Layer 3 port mirroring, see the Routing Policy Feature Guide for Routing Devices.
