General Considerations when configuring SPAN/RSPAN/ERSPAN

Keep the following things in mind when configuring SPAN/RSPAN/ERSPAN.

• Do not configure SPAN destination ports to carry normal traffic.
• Configure only physical interfaces and Port Channels as mirror source for Port based mirroring.
• Flow Based Mirroring additionally support VLAN and VE interfaces as source ports.
• The maximum span session configurable per device is 512.
• The standard limitations of forwarding apply to port mirroring when the SPAN source and destination interfaces have different speeds. For example, when traffic is mirrored from a 40G port to a 10G port, the 10G port drops traffic that exceeds the 10G rate.
• In one monitor session configuration, you can have only one SPAN source and only one SPAN destination. However, you can share the same destination port in another session with different source ports. In other words, you can use the same port as a SPAN destination in another SPAN session, which lets you have more SPAN sessions without consuming more SPAN hardware resources.
• ERSPAN Type 3 is the only supported type.
• When configuring flow based monitoring session, mirroring will be enabled when the ACL with mirror action is applied on the source interface in the same direction as in monitor session.
• VLAN configured as RSPAN VLAN should not be used for switching regular traffic.
• When configuring ERSPAN session, make sure that source IP and destination IP belongs to the same VRF.