Specifications

2-115
Catalyst 2950 and Catalyst 2955 Switch Command Reference
78-15304-01
Chapter 2 Cisco IOS Commands
monitor session
You can enable 802.1X on a port that is a SPAN or RSPAN destination port; however, 802.1X is disabled
until the port is removed as a SPAN destination. (If 802.1X is not available on the port, the switch will
return an error message.) You can enable 802.1X on a SPAN or RSPAN source port.
VLAN monitoring and VLAN filtering are mutually exclusive. If a VLAN is a source, VLAN filtering
cannot be enabled. If VLAN filtering is configured, a VLAN cannot become a source.
VLAN-based SPAN (VSPAN) refers to analyzing network traffic in a set of VLANs. All active ports in
the source VLANs become source ports for the SPAN or RSPAN session. Trunk ports are included as
source ports for VSPAN, and only packets with the monitored VLAN ID are sent to the destination port.
Trunk VLAN filter refers to analyzing network traffic on a selected set of VLANs on trunk source ports.
By default, all VLANs are monitored on trunk source ports. You can use the monitor session
session_number filter vlan vlan-id command to limit SPAN traffic on the trunk source port only to the
specified VLANs.
Examples This example shows how to create SPAN session 1 to monitor both sent and received traffic on source
interface 0/1 on destination interface 0/8:
Switch(config)# monitor session 1 source interface fastEthernet0/1 both
Switch(config)# monitor session 1 destination interface fastEthernet0/8
This example shows how to delete a destination port from an existing SPAN session:
Switch(config)# no monitor session 2 destination fastEthernet0/4
This example shows how to limit SPAN traffic only to specific VLANs:
Switch(config)# monitor session 1 filter vlan 100 - 304
This example shows how to configure RSPAN session 1 to monitor multiple source interfaces and a
VLAN and to configure the destination RSPAN VLAN and the reflector-port.
Switch(config)# monitor session 1 source interface fastEthernet0/10 tx
Switch(config)# monitor session 1 source interface fastEthernet0/2 rx
Switch(config)# monitor session 1 source interface port-channel 102 rx
Switch(config)# monitor session 1 source vlan 5 rx
Switch(config)# monitor session 1 destination remote vlan 901 reflector-port
fastEthernet 0/1
Switch(config)# end
You can verify your settings by entering the show monitor privileged EXEC command.
Related Commands Command Description
remote-span Configures an RSPAN VLAN in vlan configuration mode.
show monitor Displays SPAN and RSPAN session information.