Monitoring Interfaces
You can designate an interface to be a monitoring interface. This action
forwards the interface's incoming and outgoing traffic to another interface
and frees it for use with the Switch Port Analyzer (SPAN). You can then troubleshoot
network problems by examining traffic on other interfaces or segments.
Any interface can be a monitoring interface, with these restrictions:
- A monitoring interface must be a static-access port.
- A monitoring interface cannot be in a Fast EtherChannel or Gigabit EtherChannel
port group.
- An ATM port cannot be a monitoring interface but can be monitored.
- A monitoring interface cannot be enabled for port security.
- A monitoring interface cannot be a multi-VLAN port.
- A monitoring interface must be a member of the same VLAN as the interface
being monitored. VLAN membership changes are not allowed on monitor interfaces
and interfaces being monitored.
- A monitoring interface cannot be a dynamic-access port or a trunk port.
However, a static-access port can monitor a VLAN on a trunk port. The VLAN
monitored is the one associated with the static-access port.
The SPAN window shows you which interface,
if any, is being used as a monitoring interface. It also allows you to reassign
monitoring to another interface. To open the SPAN window, choose Port >
SPAN.
Related Web Link
"Configuring SPAN," Catalyst 3550 Multilayer Switch Software Configuration
Guide