Span Configuration Guidelines; Creating A Local Span Session - Cisco 3020 - Catalyst Blade Switch Configuration Manual

Configuring SPAN and RSPAN

SPAN Configuration Guidelines

Follow these guidelines when configuring SPAN:
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Creating a Local SPAN Session

Beginning in privileged EXEC mode, follow these steps to create a SPAN session and specify the source
(monitored) ports or VLANs and the destination (monitoring) ports:
Command
Step 1 configure terminal
Step 2 no monitor session {session_number | all |
local | remote}
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For SPAN sources, you can monitor traffic for a single port or VLAN or a series or range of ports
or VLANs for each session. You cannot mix source ports and source VLANs within a single SPAN
session.
The destination port cannot be a source port; a source port cannot be a destination port.
You cannot have two SPAN sessions using the same destination port.
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.
Entering SPAN configuration commands does not remove previously configured SPAN parameters.
You must enter the no monitor session {session_number | all | local | remote} global configuration
command to delete configured SPAN parameters.
For local SPAN, outgoing packets through the SPAN destination port carry the original
encapsulation headers—untagged, ISL, or IEEE 802.1Q—if the encapsulation replicate keywords
are specified. If the keywords are not specified, the packets are sent in native form. For RSPAN
destination ports, outgoing packets are not tagged.
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 or source VLAN are enabled.
You can limit SPAN traffic to specific VLANs by using the filter vlan keyword. If a trunk port is
being monitored, only traffic on the VLANs specified with this keyword is monitored. By default,
all VLANs are monitored on a trunk port.
You cannot mix source VLANs and filter VLANs within a single SPAN session.
On the Cisco Catalyst Blade Switch 3020 for HP, egress SPAN routed packets (both unicast and
multicast) show the incorrect source MAC address. For local SPAN packets with native
encapsulation on the destination port, the packet shows the MAC address of VLAN 1. This problem
does not appear with local SPAN when the encapsulation replicate option is used. This limitation
does not apply to bridged packets. The workaround is to use the encapsulate replicate keywords in
the monitor session global configuration command.
Purpose
Enter global configuration mode.
Remove any existing SPAN configuration for the session.
For session_number, the range is 1 to 66.
Specify all to remove all SPAN sessions, local to remove all local
sessions, or remote to remove all remote SPAN sessions.
Chapter 22 Configuring SPAN and RSPAN
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