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Catalyst 2940 Switch Software Configuration Guide
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Chapter20 Configuring SPAN
Configuring SPAN
Creating a SPAN Session and Enabling Ingress Traffic
Beginning in privileged EXEC mode, follow these steps to create a SPAN sessio n , to specify th e sour ce
and destination ports, and to enable ingress traffic on the destination port for a network security device
(such as a Cisco IDS Sensor Appliance):
This example shows how to configure the destination port for ingress traffic on VLAN 5 by u si ng a
security device that does not support 802.1Q encapsulation.
Switch(config)# monitor session 1 destination interface Fa 0/5 ingress vlan 5
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 no monitor session {session_number | all |
local | remote}Clear any existing SPAN configuration for the session.
For session_number, specify 1.
Specify all to remove all SPAN sessions, local to remove all local
sessions, or remote to remove all remote SPAN sessions.
Step3 monitor session session_number source
interface interface-id [, | -] [both | rx | tx]Specify the SPAN session and the source port (monitored port).
For session_number, specify 1.
For interface-id, specify the source port to monitor. Valid interfaces
include physical interfaces and port-channel logical interfaces
(port-channel port-channel-number).
(Optional) [, | -] Specify a series or range of interfaces. Enter a space
before and after the comma; enter a space before and after the
hyphen.
(Optional) Specify the direction of traffic to monitor. If you do not
specify a traffic direction, the source interface sends both sent and
received traffic.
•both—Monitor both received and sent traffic.
•rx—Monitor received traffic.
•tx—Monitor sent traffic.
Step4 monitor session session_number
destination interface interface-id
[encapsulation {dot1q}] [ingress vlan
vlan id]
Specify the SPAN session, the destination port (monitoring port), the
packet encapsulation, and the ingress VLAN.
For session_number, specify 1.
For interface-id, specify the destination port. Valid interf aces include
physical interfaces.
(Optional) Specify the encapsulation header for outgoing packets. If
not specified, packets are sent in native form.
•dot1q—Use 802.1Q encapsulation.
(Optional) Enter ingress vlan vlan id to enable ingress forwarding
and specify a default VLAN.
Step5 end Return to privileged EXEC mode.
Step6 show monitor [session session_number] Verify your entries.
Step7 copy running-config startup-config (Optional) Save your entries in the configuration file.