B-23
Monitoring and Analyzing Switch Operation
Traffic Mirroring
Traffic Mirroring
Mirror Features
Traffic mirroring (Intelligent Mirroring) allows you to mirror (send a copy of)
network traffic received or transmitted on a switch interface to a local
destination, such as a traffic analyzer or intrusion detection system (IDS).
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 result-
ing 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.
Mirroring destinations. Traffic mirroring supports destination devices
that are connected to the local switch:
■ Traffic can be copied to a destination connected to the same switch as the
mirroring source in a local mirroring session. Up to four local mirroring
destinations are supported on a switch.
Configuration
Notes
Using the CLI, you can make full use of the switch’s local mirroring capabili-
ties. Using the Menu interface, you can configure only local mirroring for a
group of ports and/or static trunks.
Only a single mirror port session is supported.
Mirrored frames exceeding the allowed maximum transmission unit (MTU)
size will be dropped. Also, the switch applies a 54-byte IPv4 header to mirrored
frames. For more information, including the size limitation for jumbo and non-
jumbo frames, see “Maximum Supported Frame Size” on page B-42.
Selecting mirrored traffic. You can use any of the following options to
select the traffic to be mirrored on a port or trunk interface in a local session:
Feature Default Menu CLI
Mirror CLI Quick Reference n/a n/a B-34
Configure Mirror Source disabled page B-29 page B-35
Configure Mirror Destination at Source disabled page B-29 page B-35
Display Mirror Configuration n/a page B-29 page B-38
