Cisco Catalyst 2950 - Creating a SPAN Session and Enabling Ingress Traffic

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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
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Chapter 24 Configuring SPAN and RSPAN
Configuring SPAN
This example shows how to set up a SPAN session, session 1, for monitoring source port traffic to a
destination port. First, any existing SPAN configuration for session 1 is cleared, and then bidirectional
traffic is mirrored from source port 1 to destination port 8.
Switch(config)# no monitor session 1
Switch(config)# monitor session 1 source interface fastethernet0/1
Switch(config)# monitor session 1 destination interface fastethernet0/8
encapsulation dot1q
Switch(config)# end
Creating a SPAN Session and Enabling Ingress Traffic
Beginning in privileged EXEC mode, follow these steps to create a SPAN session, to specify the source
and destination ports, and to enable ingress traffic on the destination port for a network security device
(such as a Cisco IDS Sensor Appliance):
Step 4
monitor session session_number
destination interface interface-id
[encapsulation {dot1q}]
Specify the SPAN session and the destination port (monitoring port).
For session_number, specify 1.
For interface-id, specify the destination port. Valid interfaces include
physical interfaces.
(Optional) Specify the encapsulation header for outgoing packets. If
not specified, packets are sent in native form.
• dot1q—Use IEEE 802.1Q encapsulation.
Step 5
end Return to privileged EXEC mode.
Step 6
show monitor [session session_number] Verify your entries.
Step 7
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
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.