Configuring Span; Span Configuration Guidelines; Creating A Span Session And Specifying Ports To Monitor; Removing Ports From A Span Session - Cisco Catalyst 2950 Software Manual

Configuring SPAN

Configuring SPAN
This section describes how to configure SPAN on your switch and contains this information:
•
•
•
•

SPAN Configuration Guidelines

Follow these guidelines when configuring SPAN:
•
•
•
•
•
•
•
•
•
•
•
•
•
Catalyst 2950 Desktop Switch Software Configuration Guide
10-22
SPAN Configuration Guidelines, page 10-22
Creating a SPAN Session and Specifying Ports to Monitor, page 10-23
Removing Ports from a SPAN Session, page 10-24
Displaying SPAN Status, page 10-25
SPAN is disabled by default.
Use a network analyzer to monitor ports.
Only one SPAN sessions can be active on a switch at the same time.
The destination port cannot be a source port; a source port cannot be a destination port.
You can have only one destination port.
An EtherChannel port can be a SPAN source port; it cannot be a SPAN destination port.
For a SPAN source port, you can monitor transmitted and received traffic for a single port or for a
series or range of ports.
When you configure a switch port as a SPAN destination port, it is no longer a normal switch port;
only monitored traffic passes through the SPAN destination port.
When you specify a single source port and do not specify a traffic type (Tx, Rx, or both), both is the
default.
You can configure a disabled port to be a source or destination port, but the SPAN function does not
start until the destination port and at least one source port is enabled.
The no monitor session session_number global configuration command removes a source or
destination port from the SPAN session from the SPAN session. If you do not specify any options
following the no monitor session session_number command, the entire SPAN session is removed.
A SPAN destination port never participates in any VLAN spanning tree. SPAN does include BPDUs
in the monitored traffic, so any spanning-tree BPDUs received on the SPAN destination port for a
SPAN session were copied from the SPAN source ports.
When SPAN is enabled, configuration changes have these results:
If you change the VLAN configuration of a destination port, the change is not effective until
–
SPAN is disabled.
If you disable all source ports or the destination port, the SPAN function stops until both a
–
source and destination port are enabled.
Chapter 10 Configuring the Switch Ports
78-11380-03