MPLS P Node Multicast Forwarding via ACL Capture

The patent segments the forwarding process into two distinct phases: a capture phase where packets matching ACL rules are identified, and a multicast forwarding phase where captured packets are processed according to VPLS multicast forwarding tables. This segmentation allows the P node to maintain fast unicast forwarding for non-multicast traffic while enabling point-to-multipoint multicast forwarding for captured packets, thus resolving the contradiction between forwarding speed and multicast capability.

The patent introduces an intermediary mechanism using ACL rules and a capture list to mediate between the incoming packet and the multicast forwarding table. Packets that match the ACL criteria are captured and redirected to the VPLS multicast forwarding table for further processing. This intermediary layer enables the P node to selectively apply multicast forwarding only to relevant packets, maintaining overall forwarding efficiency while providing necessary multicast functionality.

The patent enables P nodes to perform both unicast and multicast forwarding functions. By configuring ACL rules and VPLS multicast forwarding tables on P nodes, the system allows these intermediate nodes to handle both traditional unicast traffic and multicast traffic uniformly. This multi-functionality reduces deployment complexity compared to requiring separate PE nodes for multicast, as P nodes can serve dual purposes.

The patent uses the concept of copying packet processing logic from PE nodes to P nodes. The VPLS multicast forwarding table structure and processing mechanisms are copied and deployed on P nodes, allowing them to replicate the multicast forwarding behavior of PE nodes. This copying approach simplifies deployment by leveraging existing P node infrastructure and reducing the need for specialized PE node configurations.

The patent implements dynamic protection mechanisms by allowing P nodes to configure multiple egress ports and next-hop information in the VPLS multicast forwarding table. The system can dynamically switch between different egress ports based on packet capture status and network conditions. This dynamic capability enables the system to adapt to failure scenarios and provide 1+1 or 1+N line protection by selecting alternative paths when primary egress fails.

The patent applies preliminary action by pre-configuring multiple egress ports and next-hop information in the VPLS multicast forwarding table before actual packet forwarding. This preliminary setup includes configuring backup paths and egress port mappings in advance, so when packets are captured and need to be forwarded, the system can immediately utilize pre-prepared protection paths. This enables 1+1 or 1+N line protection to be activated without delay when failures occur.