Nexus Environment.
SPAN for ethernet ports monitor all traffic for source port, which sends a copy of the traffic to a destination port. The network analyzer, which is attached with destination port, analyzes the traffic that passes through source port.
Source port can be a single port or multiple ports or a VLAN, which is also called a monitored port. You can monitor all the packets for source port which is received (ingress), transmitted (egress), or bidirectional (both). A replication of the packets is sent to the destination port for analyzation.
For VLAN-based SPAN (VSPAN), all ports in VLAN are source ports. So the traffic in the VLAN is monitored. You can apply VLAN based filter on trunk port of the switch to limit SPAN traffic monitor.
The destination port is a port that was connected to the device such as SwitchProbe device or other Remote Monitoring (RMON) probe or security device that can receive and analyze the copied packets from single or multiple source port.
Switch supports multiple SPAN sessions (up to 48 sessions), but only two sessions can be run simultaneously and others are shutdown. A port of the switch is configured as either the source port or the destination port.
you can use below guide to setup one :
https://www.cisco.com/c/en/us/support/docs/switches/nexus-7000-series-switches/113038-span-nexus-config.html
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