Introduction To Port Mirroring; Understanding Layer 2 Port Mirroring - Juniper EX9200 Features Manual

CHAPTER 1

Introduction to Port Mirroring

Understanding Layer 2 Port Mirroring

Copyright © 2016, Juniper Networks, Inc.
Understanding Layer 2 Port Mirroring on page 3
Understanding Layer 2 Port Mirroring Properties on page 4
Application of Layer 2 Port Mirroring Types on page 5
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 describes
port mirroring only for Layer 2 bridging traffic (
traffic ( ) through an MX Series router, and Layer 2 VPN traffic that passes
family vpls
through a CCC ( family ccc ).
For general information about packet flow within MX Series routers and other routers,
see the Class of Service Feature Guide for Routing Devices.
In a Layer 3 environment, MX Series routers and EX Series switches support port mirroring
of IPv4 ( family inet ) and IPv6 (
mirroring, see the Routing Policies, Firewall Filters, and Traffic Policers Feature Guide.
family ethernet-switching
family inet6 ) traffic. For information about Layer 3 port
), Layer 2 VPLS
3