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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 51 Configuring SPAN and RSPAN Configuring SPAN
Configuring SPAN
The following sections describe how to configure SPAN:
SPAN Configuration Guidelines and Restrictions, page 51-7
Configuring SPAN Sources, page 51-8
Configuring SPAN Destinations, page 51-9
Monitoring Source VLANs on a Trunk Interface, page 51-9
Configuration Scenario, page 51-10
Verifying a SPAN Configuration, page 51-10
Note Entering SPAN configuration commands does not clear previously configured SPAN parameters. You
must enter the no monitor session command to clear configured SPAN parameters.

SPAN Configuration Guidelines and Restrictions

Follow these guidelines and restrictions when configuring SPAN:
You must use a network analyzer to monitor interfaces.
You cannot mix source VLANs and filter VLANs within a SPAN session. You can have source
VLANs or filter VLANs, but not both at the same time.
EtherChannel interfaces can be SPAN source interfaces; they cannot be SPAN destination interfaces.
When you specify source interfaces and do not specify a traffic type (Tx, Rx, or both), “both” is used
by default. To change from both to either “tx” or “rx,” unconfigure the co rresponding other type “rx”
or “tx” with the no monitor session {session_number} {source {interface interface_list | {vlan
vlan_IDs | cpu [queue queue_ids] } {rx | tx} command.
If you specify multiple SPAN source interfaces, the interfaces can belong to different VLANs.
You must enter the no monitor session number command with no other parameters to clear the
SPAN session number.
The no monitor command clears all SPAN sessions.
SPAN destinations never participate in any spanning tree instance. SPAN includes BPDUs in the
monitored traffic, so any BPDUs seen on the SPAN destination are from the SPAN source.
SPAN is limited to one destination port per session.
When you create a SPAN session, it sets the packet filter to good automatically and hence you will
see another configuration line:
monitor session 1 filter packet-type good rx
Reenter the monitor session 1 filter packet-type good rx command.