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Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
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Chapter 30 Configuring SPAN and RSPAN
Understanding SPAN and RSPAN
A source port has these characteristics:
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It can be monitored in multiple SPAN sessions.
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Each source port can be configured with a direction (ingress, egress, or both) to monitor.
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It can be any port type (for example, EtherChannel, Gigabit Ethernet, and so forth).
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For EtherChannel sources, you can monitor traffic for the entire EtherChannel or individually on a
physical port as it participates in the port channel.
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It can be an access port, trunk port, routed port, or voice VLAN port.
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It cannot be a destination port.
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Source ports can be in the same or different VLANs.
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You can monitor multiple source ports in a single session.
Source VLANs
VLAN-based SPAN (VSPAN) is the monitoring of the network traffic in one or more VLANs. The
SPAN or RSPAN source interface in VSPAN is a VLAN ID, and traffic is monitored on all the ports for
that VLAN.
VSPAN has these characteristics:
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All active ports in the source VLAN are included as source ports and can be monitored in either or
both directions.
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On a given port, only traffic on the monitored VLAN is sent to the destination port.
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If a destination port belongs to a source VLAN, it is excluded from the source list and is not
monitored.
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If ports are added to or removed from the source VLANs, the traffic on the source VLAN received
by those ports is added to or removed from the sources being monitored.
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You cannot use filter VLANs in the same session with VLAN sources.
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You can monitor only Ethernet VLANs.
VLAN Filtering
When you monitor a trunk port as a source port, by default, all VLANs active on the trunk are monitored.
You can limit SPAN traffic monitoring on trunk source ports to specific VLANs by using VLAN
filtering.
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VLAN filtering applies only to trunk ports or to voice VLAN ports.
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VLAN filtering applies only to port-based sessions and is not allowed in sessions with VLAN
sources.
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When a VLAN filter list is specified, only those VLANs in the list are monitored on trunk ports or
on voice VLAN access ports.
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SPAN traffic coming from other port types is not affected by VLAN filtering; that is, all VLANs are
allowed on other ports.
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VLAN filtering affects only traffic forwarded to the destination SPAN port and does not affect the
switching of normal traffic.