cbouraoui wrote:
Hi,
i've some interrogation about system class on NEXUS 5000.
A policy configured on an interface will be used if this interface is congestioned. So could some one help me to understand when the system class policy will be used, if it's not attached to a specific interface?
Thank you

The system class applies to the entire switch, so it applies across all interfaces. If you have configured your own class on a specific interface then this will take precedence over the system class. It is basically a way to apply a default QOS config that you can override.

So the system class will be used whenever there is congestion but you may well override that with your own policies. See this link for more details and for what the 2 default system classes are -

Nexus 5000 system class

Jon