KB.15.15

Traffic mirroring provides the following benefits:

• Allows you to monitor the traffic flow on specific source interfaces.

• Helps in analyzing and debugging problems in network operation resulting from a misbehaving

network or an individual client. The mirroring of selected traffic to an external device makes

it easier to diagnose a network problem from a centralized location in a topology spread

across a campus.

• Supports remote mirroring to simultaneously mirror switch traffic on one or more interfaces to

multiple remote destinations. (In remote mirroring, you must first configure the remote mirroring

endpoint—remote switch and exit port—before you specify a mirroring source for a session.)

Mirroring overview

Figure 176 (page 341) shows an example of the terms used to describe the configuration of a

sample local and remote mirroring session:

• In the local session, inbound traffic entering Switch A is monitored on port A2 and mirrored

to a destination (host), traffic analyzer 1, through exit port A15 on the switch.

A local mirroring session means that the monitored interface (A2) and exit port (A15) are on

the same switch.

• In the remote session, inbound traffic entering Switch A is monitored on port A1. A mirrored

copy of monitored traffic is routed through the network to a remote mirroring endpoint: exit

port B7 on Switch B. A destination device, traffic analyzer 2, is connected to the remote exit

port.

A remote mirroring session means that:

• The monitored interface (A1) and exit port (B7) are on different switches.

• Mirrored traffic can be bridged or routed from a source switch to a remote switch.

Figure 176 Local and remote sessions showing mirroring terms

Traffic mirroring overview 341