Configuring of MACsec for three EX4300 Switches

[switch999 at tutanota.com]

Hi,

following only the required configuration of
https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/macsec-configuring-mx-series.html
for
# Configuring MACsec Using Static Connectivity Association Key (CAK) Mode

works fine for two switches, but with a third EX4300 in the middle not.

Thus, could anyone please help what is required to ensure connectivity through
three EX4300? 

Even the configuration (A; with several tries) on the outer sides switches such as
e.g. given for (one port) per switch
jack at cs2# set security macsec connectivity-association ca1 mka eapol-address provider-bridge  
jack at cs2# set security macsec connectivity-association ca1 mka eapol-address lldp-multicast      
jack at cs2# set protocols layer2-control mac-rewrite interface ge-0/0/13 protocol ieee8021
worked not for the three EX4300.

Tunneling through a EX4200, in the middle (via vlan, snippet see below) worked fine, even without the  
configuration (A) at the outer sides switches, only with the most important commands
given in https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/macsec-configuring-mx-series.html.

Any idea why tunneling through the middle EX4300 failed? (Used version: 17.3R3-S9.3!)

Regards,
Jack


# PS: What is the equivalent code for EX4300 from the EX4200 code
       vlan-id 55;  
       dot1q-tunneling {
           layer2-protocol-tunneling {
               all;
           }