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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter15 Configuring SPAN
Configuring SPAN
•The no monitor session session_number global configuration command removes a source or
destination port from the SPAN session or removes a source VLAN from the SPAN session. If you
do not specify any options following the no monitor session session_number command, the entire
SPAN session is removed. The no monitor global configuration command also clears all SPAN
sessions.
•A SPAN destination port never participates in any VLAN spanning tree. SPAN does include BPDUs
in the monitored traffic, so any spanning-tree BPDUs received on the SPAN destination port for a
SPAN session were copied from the SPAN source ports.
•When SPAN is enabled, configuration changes have these results:
–
If you change the VLAN configuration of a destination port, the change is not effective until
SPAN is disabled.
–
If you disable all source ports or the destination port, the SPAN function stops until both a
source and destination port are enabled.
–
If the source is a VLAN, the number of ports being monit ored c hang es when y ou mov e a
switched port in or out of the monitored VLAN.
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:
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 no monitor session session_number Clear any existing SPAN configuration for the session.
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 or 2.
For interface-id, specify the source port to monitor. Valid interfaces
include physical interfaces and port-channel logical i nte rf ace s
(port-channel port-channel-number).
(Optional) [, | -] —Specify a series or range of interfaces. This option
is valid when monitoring only received traffic . Enter a space af ter 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 transmitted
and received traffic.
•both—Monitor both received and transmitted traffic.
•rx—Monitor received traffic.
•tx—Monitor transmitted traffic.