Nexus 9508 - SPAN Limitations

[ChristopherMellish1980]

Good day,

Active SPAN or ERSPAN sessions14

4 to 32, based on the number of line cards and the session configuration

14. "This limitation might also apply to Cisco Nexus 9500 Series switches, depending on the SPAN or ERSPAN source's forwarding engine instance mappings."

Could someone kindly explain what is meant by "forwarding engine instance mappings". I am trying to understand why I am limited to only four SPAN sessions.

[Sergiu.Daniluk]

Hello,

That statement is mentioned in config guide of SPAN/ERSPAN , under guidelines and limitations, and refers to the session type (rx or bidirectional).  The reason why you can only have 4 ERSPAN session is simple - it is a hardware limitation:

A single forwarding engine instance supports four ERSPAN sessions. For Cisco Nexus 9300 Series switches, if the first three sessions have bidirectional sources, the fourth session has hardware resources only for Rx sources. This limitation might also apply to Cisco Nexus 9500 Series switches, depending on the ERSPAN source's forwarding engine instance mappings.

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/system_management/configuration/guide/b_Cisco_Nexus_9000_Series_NX-OS_System_Management_Configuration_Guide_7x/b_Cisco_Nexus_9000_Series_NX-OS_System_Management_Configuration_... 

Regards,

Sergiu