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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 monitor ing is similar to port monitoring. Be ginning in pri vileged EXEC mode, follo w these steps
to specify VLANs to monitor:
To remove one or more source VLAN s or destination ports from t he 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 glo bal co nfigurat ion c omm and.
This example shows how to clear any existing configuration on SPAN session 2, configure SPAN session
2 to monitor received traffic on all por ts belong ing to VLANs 1 throu gh 3, and send it t o 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 globa l configurati on mode.
Step 2 no monitor sessio n { session_number | all
| local | remote}Clear any existing SPAN configuration for the session.
For session_number, spec ify 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 s ession session_number source
vlan vlan-id [, | -] rx Specify the SPAN session and the sour ce VLANs (monitored VLANs).
You can monitor only received (rx) traffic on VLANs.
For session_number, spec ify 1 or 2.
For vlan-id, the range is 1 to 4094; do not enter leading zeros.
(Opti onal) Us e a comm a (,) to specify a series of VLANs, or use a
hyphen (-) to specify a range of VLANs. Enter a space after the comma;
enter a spac e before a nd after the hyphen.
Step 4 monitor s ession session_number
de st ina tio n int erf ace interface-id
[encapsulation {dot1q | isl}]
Specify the SPAN session and the destination port (monitoring port).
For session_number, spec ify 1 or 2.
For interface-id, specify the destination port. Valid interfaces include
physical in terfaces.
(Optiona l) Specify the encapsul ation he ader for outgoi ng packets. If
not s peci fied, p ack ets ar e sen t in na tive form .
•isl—U se I SL en capsu la tion.
•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 (Optiona l) Save your entries in the co nfigurati on file.