Inclusive provider tunnels of type mLDP are supported in OISM PEs. These tunnels can be used to transport multicast flows from root PEs to leaf PEs while preventing multiple copies of the same multicast packet on the same link.
Figure 1 illustrates the difference between using Ingress Replication (IR) and inclusive mLDP provider tunnels in OISM. With a source S1 connected to BD1 and sending a flow to G1, if IR is used, the multicast traffic is only sent to PEs with receivers for (S1,G1). However, if an inclusive mLDP tunnel on PE1 is used (right side of Figure 1) the multicast flow is sent to all the PEs in the tenant domain. For example, PE3 receives the flow only to drop it because there are no local receivers.
mLDP tunnels are referred to as Inclusive BUM tunnels, because, although IP multicast traffic uses these tunnels, any BUM frame is also distributed to all PEs in the tenant. For example, in Figure 1 (right hand side), any BUM frame generated by any host connected to BD1 in PE1 uses the mLDP tunnel and is also sent to PE3.
The use of mLDP-inclusive provider tunnels in OISM requires the following configuration and procedures to be enabled on the PEs.
All the PEs in the OISM tenant domain that need to transmit or receive multicast traffic on an mLDP tree in a BD, are configured with the config>service>vpls>provider-tunnel>inclusive>owner bgp-evpn-mpls and config>service>vpls>provider-tunnel>inclusive>mldp commands.
The PEs attached to the sources (root PEs) should be configured with the config>service>vpls>provider-tunnel>inclusive>root-and-leaf command on the ordinary BDs, and the PEs attached to the receivers should be configured as root-and-leaf or leaf-only.
The PEs attached to the receivers (leaf PEs) need to be configured using the ingress-repl-inc-mcast-advertisement command on the BDs or SBDs. This ensures the leaf PEs advertise a label in the IMET routes so that the root PEs can create EVPN-MPLS destinations to the leaf PEs and add them to their MFIB. Having EVPN-MPLS destinations in the MFIB is required on the root PE to use the mLDP tunnel for the multicast traffic.
The SBD must always be configured as leaf-only in all PEs, because the SBD mLDP tree is not used to transmit IP multicast.
For the IMET and SMET routes to be exported and imported with the correct route targets, no vsi-import or vsi-export policies should be configured on the ordinary BDs and the SBDs.
Assuming the above guidelines are followed, and as illustrated in Figure 1 (right side), the root PE (PE1) that is attached to the source in BD1 sends the multicast traffic in an mLDP tree that is joined by leaf PEs either on BD1 (if BD1 is exists) or on the SBD (if BD1 does not exist on the leaf PE).