MX config:
interfaces {
    lt-0/0/0 {
        description "Tunnel Interface";
        unit 0 {
            description "c1 tunnel";
            encapsulation ethernet-ccc;
            peer-unit 1;
        }
        unit 1 {
            encapsulation ethernet;
            peer-unit 0;
            family inet {
                address 10.42.146.85/30;  <--- /30 between MX and CE
            }
        }
    }
}
protocols {
mpls {
        label-switched-path FROM-MX-TO-EX-C1 {
            to 10.42.146.1; <--- Loopback on EX
            no-cspf;
        }
    }
connections {
        remote-interface-switch C1 {
            interface lt-0/0/0.0;
            transmit-lsp FROM-MX-TO-EX-C1;
            receive-lsp FROM-EX-TO-MX-C1;
        }

}



EX4550 config:
ge-0/0/3 {  <-- Interface facing CE
        description c2;
        ether-options {
            no-flow-control;
        }
        unit 0 {
            family ccc;
        }
    }
}

protocols {
mpls {
        label-switched-path FROM-EX-TO-MX-C1 {
            to 10.52.127.145; <---- Loopback of MX
            no-cspf;
        }

}
connections {
        remote-interface-switch c1 {
            interface ge-0/0/3.0;
            transmit-lsp FROM-EX-TO-MX-C1;
            receive-lsp FROM-MX-TO-EX-C1;
        }
}