Cisco Systems WSC4500X16SFP Configuring SPAN

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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter37 Configuring SPAN and RSPAN
Configuring SPAN
•You cannot use filter VLANs in the same session with VLAN sources.
•You can monitor only Ethernet VLANs.
SPAN Traffic
You can use local SPAN to monitor all network traffic, including multicast and bridge protocol data unit
(BPDU) packets, Cisco Discovery Protocol (CDP), VLAN Trunk Protocol (VTP), Dyn amic Trunking
Protocol (DTP), Spanning Tree Protocol (STP), and Port Aggregation Proto col (PAgP) packets. You
cannot use RSPAN to monitor Layer 2 protocols. (See the “RSPAN Configuration Guidelines” section
on page 37-16 for more information.)
In some SPAN configurations, multiple copies of the same source packet are sent to the SPAN
destination port. For example, a bidirectional (both Rx and Tx) SPAN session is configured fo r the
sources a1 Rx monitor and the a2 Rx and Tx monitor to destination port d1. If a packet enters the switch
through a1 and is switched to a2, both incoming and outgoing packets are sent to destination port d1.
Both packets are the same (unless a Layer-3 rewrite occurs, in which case the packets are different
because of the added Layer 3 information).
SPAN and RSPAN Session Limits
You can configure up to two simultaneous SPAN sessions containing ingress sources and up to four
simultaneous SPAN sessions containing egress sources. Bidirectional sources count as both ingress and
egress. RSPAN destination sessions count as a session containing an ingress source.
Default SPAN and RSPAN Configuration
Table37-1 shows the de fault SPAN and RSPAN configuration.
Configuring SPAN
The following sections describe how to configure SPAN:
•SPAN Configuration Guidelines and Restrictions, page 37-7
•Configuring SPAN Sources, page 37-8
•Configuring SPAN Destinations, page 37-9
•Monitoring Source VLANs on a Trunk Interface, page 37-9
Table37-1 Default SPAN and RSPAN Configuration
Feature Default Setting
SPAN state Disabled.
Source port traffic to monitor Both received and sent traffic (both).
Filters All VLANs, all packet types, all address types.
Encapsulation type (destination port) Native form (no encapsulation type header).
Ingress forwarding (destination port) Disabled.
Host learning (destination port) Disabled.