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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 21 Configuring SPAN and RSPAN
Configuring SPAN
Specifying VLANs to Monitor
VLAN monitoring is similar to port monitoring. Beginning in privileged EXEC mode, follow these steps
to specify VLANs to monitor:
To remove one or more source VLANs or destination ports from the SPAN session, use the no monitor
session session_number source vlan vlan-id rx global configuration command or the no monitor
session session_number destination interface interface-id global configuration command.
This example shows how to clear any existing configuration on SPAN session 2, configure SPAN session
2 to monitor received traffic on all ports belonging to VLANs 1 through 3, and send it to destination
port 7. The configuration is then modified to also monitor received traffic on all ports belonging to
VLAN 10.
Switch(config)# no monitor session 2
Switch(config)# monitor session 2 source vlan 1 - 3 rx
Switch(config)# monitor session 2 destination interface gigabitethernet0/7
Switch(config)# monitor session 2 source vlan 10 rx
Switch(config)# end
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 or 2.
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
vlan vlan-id [, | -] rx
Specify the SPAN session and the source VLANs (monitored VLANs).
You can monitor only received (rx) traffic on VLANs.
For session_number, specify 1 or 2.
For vlan-id, the range is 1 to 4094; do not enter leading zeros.
(Optional) Use a comma (,) to specify a series of VLANs, or use a
hyphen (-) to specify a range of VLANs. Enter a space after the comma;
enter a space before and after the hyphen.
Step 4
monitor session session_number
destination interface interface-id
[encapsulation {dot1q | isl}]
Specify the SPAN session and the destination port (monitoring port).
For session_number, specify 1 or 2.
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.
• isl—Use ISL encapsulation.
• dot1q—Use 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.