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| 9.2 |  | RSPAN |
| 9.2.1 |  | RSPAN overview |

RSPAN is an implementation of SPAN designed to support source ports, source VLANs, and destination ports across different switches. RSPAN allows remote monitoring of multiple switches across a network. An RSPAN requirement is that participating switches must have the enhanced software image (EI) installed. A significant difference in RSPAN from SPAN and VSPAN is that RSPAN cannot be used to monitor Layer 2 protocols including BPDUs.

The first step in creating an RSPAN session is to create an RSPAN VLAN dedicated to that particular session in all participating switches.

RSPAN uses reflector ports to enable RSPAN to reproduce traffic from source ports residing on remote switches to the destination port on the local switch. Except for traffic that is required for the RSPAN session, RSPAN reflector ports work just like RSPAN destination ports. Reflector ports only forward packets received or sent by source ports, and do not receive or forward any other network traffic.

RSPAN source ports can be trunks carrying the RSPAN VLAN. Local SPAN and RSPAN do not monitor the RSPAN traffic in the RSPAN VLAN seen on a source trunk.

RSPAN traffic from source ports or source VLANs is switched to the RSPAN VLAN, and is then forwarded to destination ports that are also in the RSPAN VLAN. The source, port or VLAN, in an RSPAN session can be different on different source switches. However, if internet routers are used as sources for an RSPAN session, they must have the same VLAN’s as RSPAN sources.

Like SPAN, RSPAN does not affect the switching of network traffic on source ports. A copy of the packets received or sent by the source interfaces are sent to the destination interface. Except for traffic that is required for the RSPAN session, reflector ports and destination ports do not receive or forward traffic.