VPLS: Hierarchical VPLS

Hierarchical LDP-based VPLS requires a full mesh of tunnel LSPs between all the PE routers that participate in the VPLS service. Using hierarchical connectivity reduces signaling and replication overhead to facilitate large-scale deployments. In a typical IPTV solution, IPTV sources are in the public domain and the subscribers are in the private VPN domain. For an efficient delivery of multicast data from the IPTV source to the set-top boxes or to subscribers in the private domain using the access devices (ACX Series routers in this case), P2MP LSPs and MVPN are necessary. Because VPLS and MVPN are not supported on ACX routers, an alternative approach is used to achieve hierarchical VPLS (HPVLS) capabilities. The subscriber devices are connected to a VPLS or a Layer 3 VPN domain on the ACX Series (access) router and they are configured to import the multicast routes. The support for PIM snooping in Layer 3 interfaces, IGMP snooping in Layer 2 networks, IRB interfaces, and logical tunnel interfaces enables HVPLS support.