Understanding Port Mirroring On Ex Series Switches; Port Mirroring Overview - Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual

CHAPTER 138
Port Mirroring
Port Mirroring—Overview

Understanding Port Mirroring on EX Series Switches

Copyright © 2010, Juniper Networks, Inc.
Port Mirroring—Overview on page 3833
Examples: Port Mirroring Configuration on page 3837
Configuring Port Mirroring on page 3849
Verifying Port Mirroring Configuration on page 3854
Configuration Statements for Port Mirroring on page 3855
Operational Commands for Port Mirroring on page 3868
Understanding Port Mirroring on EX Series Switches on page 3833
Use port mirroring to facilitate analyzing traffic on your Juniper Networks EX Series
Ethernet Switch on a packet level. Use port mirroring as part of monitoring switch traffic
for such purposes as enforcing policies concerning network usage and file sharing, and
identifying sources of problems on your network by locating abnormal or heavy bandwidth
usage from particular stations or applications.
Port mirroring copies packets to either a local interface for local monitoring or to a VLAN
for remote monitoring. You can use port mirroring to copy these packets:
Packets entering or exiting a port
Packets entering a VLAN on Juniper Networks EX2200, EX3200, EX4200, or EX4500
Ethernet Switches
Packets exiting a VLAN on Juniper Networks EX8200 Ethernet Switches
This topic describes:
Port Mirroring Overview on page 3833
Port Mirroring Terminology on page 3836

Port Mirroring Overview

Port mirroring is needed for traffic analysis on a switch because a switch, unlike a hub,
does not broadcast packets to every port on the device. The switch sends packets only
to the port to which the destination device is connected. You configure port mirroring on
3833