Junos OS

i want to limit to 2G , how to add the firewall policer in to the interfaces xe-0/0/46  unit ?

root@# show interfaces xe-0/0/46
description "[TRANSIT]  ;";
unit 0 {
family ethernet-switching {
interface-mode trunk;
vlan {
members V3000;
}
}
}

You could use a single rate two color policer for this purpose as outlined here.

https://www.juniper.net/documentation/en_US/junos12.3/topics/reference/general/policer-summary-configuration-two-color.html

This shows both how to configure the policer on the left and where to apply the policer to the interface on the right in the sample configurations.

You can also do something similar to this example:

class-of-service {
        interfaces {
                xe-0/0/46 {
                        shaping-rate 2g;
                }


firewall {
    family ethernet-switching {
        filter 2G-limit {
            term 1 {
                then policer 2G-limit;
            }
        }
    }
    policer 2G-limit {
        if-exceeding {
            bandwidth-limit 2g;
            burst-size-limit 1250k;
        }
        then discard;
    }
}

xe-0/0/46 {
        unit 0 {
                family ethernet-switching {
                        vlan {
                                members V3000;
                        }
                        filter {
                                input 2G-limit;
                        }
                }
        }

}