Span Configuration Guidelines - Cisco WS-X6066-SLB-APC - Content Switching Module Software Manual

Configuring SPAN

SPAN Configuration Guidelines

Follow these guidelines when configuring SPAN:
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In software releases prior to software release 8.4(1), if you use the set span command without the create
Caution
keyword, and you have only one session configured, the session is overwritten. If there are two SPAN
sessions already configured, you receive an error message. If a matching destination port exists, the
particular session is overwritten (with or without specifying the create keyword). If you specify the
create keyword and there is no matching destination port, the session is created.
In software release 8.4(1) and later releases, the create keyword has been removed from the set span
command. When you enable a SPAN session without the create keyword, and another session is
available, the first session is not overwritten.
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
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Use a network analyzer to monitor ports.
For SPAN source ports, SPAN is not supported with ATM ports; it works with Ethernet
10/100/1000-Mbps ports and 10-Gbps ports.
When enabled, SPAN uses any previously entered configuration; if you have not entered any
configuration commands, SPAN uses default parameters.
If you specify multiple SPAN source ports, the ports can belong to different VLANs.
See the "SPAN and RSPAN Session Limits" section on page
RSPAN sessions can coexist with SPAN sessions within the SPAN/RSPAN limits described in the
"SPAN and RSPAN Session Limits" section on page
The inpkts option is disabled by default. Use the inpkts keyword with the enable option to allow
the SPAN destination port to receive normal incoming traffic. Use the disable option to prevent the
SPAN destination port from receiving normal incoming traffic.
When you enable the inpkts option, a warning message notifies you that the destination port does
not support the Spanning Tree Protocol (STP) and may cause loops if you enable this option.
Learning is enabled by default. Use the inpkts keyword with the learning option to enable or disable
learning for a specific port.
You can specify a Multilayer Switch Module (MSM) port as the SPAN source port. However, you
cannot specify an MSM port as the SPAN destination port.
When you configure multiple SPAN sessions, the destination module number/port number must be
known to index the particular SPAN session.
If any VLANs on SPAN source port(s) are blocked by spanning tree, you may see extra packets
transmitted on the destination port that were not actually transmitted out the source port(s). The
extra packets seen at the destination port are packets sent through the switch fabric to the source port
and then blocked by spanning tree at the source port.
Chapter 38 Configuring SPAN and RSPAN
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