ACX Support for BGP MVPN

ACX7100-32C and ACX7100-48L routers running Junos Evolved release 22.1R1 support BGP/MPLS MVPN (also known as “next generation,” or “NG,” MVPN) running on multipoint LDP (MLDP P2MP) provider tunnels, where BGP MVPN is the intra-AS and PIM-SM/SSM is the data plane.

The following considerations apply:

• BGP intra-AS auto-discovery occurs at the level of PE, MVPN and the binding of a MVPN to an Inclusive Tree.
  • For a PE in a MVPN sender site set to discover PEs in the MVPN receiver sites set, the AD route is imported by a PE attached to a sender site into the VRF only if the import RT matches the AD route RT. A PE in the receiver sites set exports the receiver sites RT.
  • For a PE in a MVPN receiver sites set to discover PEs in the MVPN sender sites set, the AD route is imported by a PE attached to a receiver site into the VRF only if the import RT matches the AD route RT. A PE in the sender sites set exports the sender sites RT.
  • Constrained set up of Inclusive P-Tunnels and the binding of a MVPN to such tunnels to construct an I-PMSI. A PE in the sender site set of a particular MVPN advertises an intra-AS AD route that carries the P-Tunnel identifier in a new attribute. The PE sends packets received from the sender sites of this MVPN on the P-Tunnel. A PE in the receiver site set of this MVPN associates this P-tunnel with the VRF. The PE in the receiver site forwards packets received on the P-tunnel using the VRF.
• MLDP Inclusive Intra-AS P-Tunnels. MLDP P2MP is supported as the data plane for Inclusive P-Tunnels. Aggregate trees are not supported, thus a separate P-tunnel is setup for a given MVPN.
  • A provider must configure MLDP P2MP as the P-Tunnel technology on each PE in the MVPN that belongs to the sender site set. By default a PE belongs to both sender site set and receiver site set. Configuration can be used to change the default behavior.
  • A provider must configure the same P-Tunnel MLDP P2MP technology on all PEs in the MVPN.
  • A provider must also configure MLDP P2MP on all P routers and MUST configure in the PEs.
  • The goal is to provide a label-based switching in the core for the multicast traffic from the CE site to the other CE site.
• MLDP MP2MP Inclusive Intra-AS P-Tunnels are not supported in release 22.1R1.
• C-multicast Routing Information Exchange using BGP provides the intra-AS C-multicast routing exchange using BGP (as covered in BGP-MVPN) and which provides the following:
  • Constrained exchange of C-multicast routes using BGP is done by:
    • Constraining distribution of unicast VPN-IPv4 routes. A PE connected to a receiver site cannot join a C-S unless it has a unicast route to C-S, which is handled by the unicast (VPN-IPv4) routing.
    • Using C-multicast routes to pass MVPN C-multicast routing information from PEs connected to sites in receiver sites set to PEs connected to sites in sender sites set.
    • Using Route Import Extended Community to control import of C-multicast routes into a particular VRF [BGP-MVPN]. The Route Import Extended Community is distinct per VRF. It contains the PE's IP address and number (which are local to the PE). C-multicast route is accepted into a given VRF only if the route target carried by the C-multicast route is equal to the route import associated with the VRF.
  • Supporting MVPN customers who use PIM-SM in the SSM mode. This requires only one type of C-multicast routes, the Source Tree Join.
  • Supporting MVPN customers who use PIM-SM in the SM mode. This is provided by using only one type of C-multicast route, the Source Tree Join, which can be enabled because:
    • Each MVPN uses the existing IP multicast mechanisms to enable C-RPs in the PEs.
    • The PEs maintain information about active sources (S,G) for a given MVPN.
    • BGP AD routes are used to distribute information about active sources (S,G) within a given MVPN among all PEs with that MVPN.
    • BGP Source Tree Join C-multicast routes are used to inform PEs connected to active sources that there are receivers for (S,G) connected to some other PEs.