What Cisco feature allows you to monitor traffic on one or more ports or more VLANs and send the monitored traffic to one or more destination ports?

The correct answer is ERSPAN, which stands for Encapsulated Remote Switched Port Analyzer. This feature allows network administrators to monitor traffic on specified ports or VLANs and send that monitored traffic to a remote destination for analysis. The encapsulation part of ERSPAN indicates that the traffic being mirrored can be sent across different networks, which allows for streamlined analysis even when the source and destination are not located on the same physical switch.

ERSPAN is especially useful in environments where traffic needs to be monitored outside of the local network segment, ensuring that valuable visibility into the traffic patterns and performance metrics can still be maintained. It encapsulates the mirrored packets in GRE (Generic Routing Encapsulation) packets, allowing them to traverse IP networks seamlessly.

In contrast, SPAN, which allows for mirroring traffic to a destination port on the same switch, does not support remote traffic monitoring. RSPAN extends the capabilities of SPAN to allow traffic to be sent to a different switch over a VLAN, but it does not encapsulate the traffic in a manner that would allow it to be monitored over an IP network. While MIRROR might be a term associated with such features, it is not a specific Cisco technology but rather a general description of the action being performed.

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