The Remote SPAN (RSPAN) feature enables you to remotely monitor traffic for one or more SPAN sources distributed in one or more source switches in a Fibre Channel fabric. The SPAN destination (SD) port is used for remote monitoring in a destination switch. A destination switch is usually different from the source switch(es) but is attached to the same Fibre Channel fabric. You can replicate and monitor traffic in any remote Cisco MDS 9000 Family switch or director, just as you would monitor traffic in a Cisco MDS source switch.

The RSPAN feature is nonintrusive and does not affect network traffic switching for those SPAN source ports. Traffic captured on the remote switch is tunneled across a Fibre Channel fabric that has trunking enabled on all switches in the path from the source switch to the destination switch. The Fibre Channel tunnel is structured using trunked ISL (TE) ports. In addition to TE ports, the RSPAN feature uses two other interface types, as shown in Figure 11-6.

SD ports: A passive port. The FC analyzer can obtain remote SPAN traffic from these passive ports.

ST ports: SPAN tunnel (ST) ports are entry point ports in the source switch for the RSPAN Fibre Channel tunnel. ST ports are special RSPAN ports and cannot be used for normal Fibre Channel traffic.

RSPAN has the following advantages:

Enables nondisruptive traffic monitoring at a remote location

Provides a cost-effective solution by using one SD port to monitor remote traffic on multiple switches

Works with any Fibre Channel analyzer

Is compatible with the Cisco MDS 9000 Port Analyzer adapters

Does not affect traffic in the source switch but shares the ISL bandwidth with other ports in the fabric

Figure 11-6 RSPAN Transmission

An FC tunnel is a logical data path between a source switch and a destination switch. The FC tunnel originates from the source switch and terminates at the remotely located destination switch. RSPAN uses a special Fibre Channel tunnel (FC tunnel) that originates at the ST port in the source switch and terminates at the SD port in the destination switch. You must bind the FC tunnel to an ST port in the source switch and map the same FC tunnel to an SD port in the destination switch. After the mapping and binding are configured, the FC tunnel is referred to as an RSPAN tunnel, as shown in Figure 11-7.