Only one SPAN destination for a SPAN session is supported. If you attempt to add another destination interface to a session that already has a destination interface configured, you will get an error. You must first remove a SPAN destination interface before changing the SPAN destination to a different interface.

A particular SPAN session can either monitor VLANs or monitor individual interfaces—you cannot have a SPAN session that monitors both specific interfaces and specific VLANs. If you first configure a SPAN session with a source interface, and then try to add a source VLAN to the same SPAN session, you will get an error. You will also get an error if you configure a SPAN session with a source VLAN and then try to add a source interface to that session. You must first clear any sources for a SPAN session before switching to another type of source.

If you enter the filter keyword on a monitored trunking interface, only traffic on the set of specified VLANs is monitored.

Port channel interfaces are displayed in the list of interface options if you have them configured. VLAN interfaces are not supported. However, you can span a particular VLAN by entering the monitor session session source vlan vlan-id command.

Examples

This example shows how to add a source interface to a SPAN session:

Switch(config)#  monitor session source interface fa2/3
Switch(config)#

 

This example shows how to remove a source interface from a SPAN session:

Switch(config)# no monitor session source interface fa2/3
Switch(config)#

 

This example shows how to limit SPAN traffic to specific VLANs:

Switch(config)# monitor session filter vlan 100 304
Switch(config)#

Related Commands

show monitor

 

show monitor

Use the show monitor command to display SPAN session information.

show monitor [session session-number]

Syntax Description

session session-number

(Optional) Keyword and variable to specify the number of the session; valid values are 1 and 2.

 

Defaults

This command has no default settings.

Command Modes

EXEC mode.

Command History

Release  Modification 

12.1(8a)EW

This command was introduced on the Catalyst 4006 switch.

 

Examples

This example shows how to display SPAN information for a specific session:


 

This example shows how to display SPAN information for a specific session beginning with the line that starts with "Destination":

Related Commands

monitor session