Setting up a mirrored port

Below will show you how to setup port-mirroring;

Step 1;

Make sure the output port is a generic port, no vlans and or VOIP/tagging.

[edit ethernet-switching-options]
+   analyzer port-mirror {
+       input {
+           ingress {
+               interface ge-0/0/22.0;
+           }
+           egress {
+               interface ge-0/0/22.0;
+           }
+       }
+       output {
+           interface {
+               ge-0/0/21.0;
+           }
+       }
+   }

set ethernet-switching-options analyzer port-mirror input egress interface ge-0/0/22
set ethernet-switching-options analyzer port-mirror input ingress interface ge-0/0/22


set ethernet-switching-options analyzer port-mirror output interface ge-0/0/22

That should do the trick!