MPLS in the SDN Era

Chapter 5. Multicast VPN

After exploring Internet Multicast over MPLS, let’s see Multicast VPN (MVPN) over MPLS. The three implemented models in growing scalability order, are:

• Rosen mLDP, already discussed in Chapter 4 and only implemented in IOS XR. In the terms of Table 4-1, it is S2, A1, C2, E3, T2, Y4.

• VRF In-Band mLDP, only implemented in IOS XR. In the terms of Table 4-1, this model is S2, A2, C2, E3, T2, Y3. It is nearly identical to the one discussed for Internet Multicast in Chapter 4, but it also encodes VPN-specific information (the RD of the S unicast route) in the LDP opaque value.

• BGP Multicast VPN, formerly known as Next-Generation MVPN or NG-MVPN. It is implemented by both Junos and IOS XR. In the terms of Table 4-1, this model is S2, A3, C3, [E1, E2, E3], [T0, T1, T2, T3, T4], [Y1, Y2, Y3, Y4]. Not all the combinations make sense and/or are supported, though.

As of this writing, the only interoperable solution is BGP MVPN. Fortunately, it is the most flexible and scalable flavor of them all. Table 4-1 lists the different C-Multicast Architectures: Out-of-band (A3) is more scalable than Hop-by-Hop Inter-PE (A2), which in turn is more scalable than Direct Inter-PE (A1). The only implemented solution that is compatible with the A3 model is precisely BGP MVPN.

MVPN is a multidimensional universe, whose richest galaxy is BGP MVPN. Its Out-of-Band signaling approach, which decouples service from transport, makes BGP MVPN flavors and use cases quite extensive. ...