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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 24 Configuring SPAN and RSPAN
Configuring SPAN
If you disable all source ports or the destination port, the SPAN function stops until both a
source and the destination port are enabled.
Creating a SPAN Session and Specifying Ports to Monitor
Beginning in privileged EXEC mode, follow these steps to create a SPAN session and specify the source
(monitored) and destination (monitoring) ports:
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 17 to destination port 8.
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.
Step 3 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.
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.