Ethernet loopback testing on 9000 switch

[andrewmcca]

Is there any way of creating a software loopback on ethernet ports on a Cisco switch?  There used to be on older WAN interfaces so you could perform loopback testing (e.g. testing a fibre link with a tester on the remote end.)

I'm NOT referring to loopback interfaces   They've a totally different function.

[acampbell]

Hi,

Looping ethernet ports should generate alarm

s and possibly shut ports if loopback is detected.
Therefore soft loops could create LAN havoc.

If you must loop you would be better with a hard loop but ensure you are running a protection protocol like UDLD.
When a loop is detected the port should close almost instantly for the error diable timeout priod ot until you re-open. You do not want MAC addresses looping round ports as this will really screw up the LAN or VLAN.

Hope this helps