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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 21 Configuring SPAN and RSPAN
Configuring RSPAN
Configuring RSPAN
This section describes how to configure RSPAN on your switch. It contains this configuration
information:
• RSPAN Configuration Guidelines, page 21-14
• Creating an RSPAN Session, page 21-15
• Creating an RSPAN Destination Session, page 21-16
• Removing Ports from an RSPAN Session, page 21-17
• Specifying VLANs to Monitor, page 21-18
• Specifying VLANs to Filter, page 21-19
RSPAN Configuration Guidelines
Follow these guidelines when configuring RSPAN:
• All the items in the “SPAN Configuration Guidelines” section on page 21-8 apply to RSPAN.
Note As RSPAN VLANs have special properties, you should reserve a few VLANs across your network for
use as RSPAN VLANs; do not assign access ports to these VLANs.
Note You can apply an output access control list (ACL) to RSPAN traffic to selectively filter or monitor
specific packets. Specify these ACLs on the RSPAN VLAN in the RSPAN source switches.
• RSPAN sessions can coexist with SPAN sessions within the limits described in the “SPAN and
RSPAN Session Limits” section on page 21-8.
• For RSPAN configuration, you can distribute the source ports and the destination ports across
multiple switches in your network.
• A port cannot serve as an RSPAN source port or RSPAN destination port while designated as an
RSPAN reflector port.
• When you configure a switch port as a reflector port, it is no longer a normal switch port; only
looped-back traffic passes through the reflector port.
• RSPAN does not support BPDU packet monitoring or other Layer 2 switch protocols.
• The RSPAN VLAN is configured only on trunk ports and not on access ports. To avoid unwanted
traffic in RSPAN VLANs, make sure that the VLAN remote-span feature is supported in all the
participating switches. Access ports on the RSPAN VLAN are silently disabled.
• RSPAN VLANs are included as sources for port-based RSPAN sessions when source trunk ports
have active RSPAN VLANs. RSPAN VLANs can also be sources in SPAN sessions.
• You can configure any VLAN as an RSPAN VLAN as long as these conditions are met:
–
No access port is configured in the RSPAN VLAN.
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The same RSPAN VLAN is used for an RSPAN session in all the switches.
–
All participating switches support RSPAN.