FRRouting Container Interfaces support for MPLS

I am trying to work with frrouting container for MPLS packets. My host operating system is Ubuntu 16.04 (64 bit LTS). Docker version is 18.09.7. And FRRouting version is 7.2.

That container works beautifully (many kudos and thanks to all the developers) however I am unable to receive MPLS labelled packets on any of the FRR based routers. If I do interface packet capturing I can see the send FRR routers transmit the correct labeled packet but receiving (middle) router just silently drops them.

I’ve already enabled MPLS support in host kernel using mpls_iptunnel and mpls_router modules and also MPLS label input is set to “1” in /etc/sysctl.conf on host machine:

#Enable MPLS Label processing on all interfaces
net.mpls.platform_labels=100000
net.mpls.conf.lo.input=1
net.mpls.conf.enp0s25.input=1
net.mpls.conf.docker0.input = 1

I’m unable to figure out how to fix it. Any ideas / suggestions please ?

Thanks.