Multicast Packet Forwarding via Layer 3 Switch Mediation
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Solution Overview
Problem
Existing network systems face bandwidth issues due to unnecessary forwarding of multicast packets to devices that do not request them, leading to inefficient use of bandwidth resources.
Innovation Solution
Implementing a network system with communication apparatuses that store receiving port information for multicast groups and use forwarding units to forward multicast packets only from designated forward ports, preventing flooding to irrelevant devices by using IGMP and PIM protocols for entry and withdrawal requests, and TRILL for route redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Layer 2 switch forwards multicast packets from all ports except the receiving port (flooding), then multicast packets reach all devices in the VLAN, but bandwidth is wasted on devices that do not request the packets
Solution Approach 1:
The patent extracts and removes the unnecessary flooding function from Layer 2 switches. Instead of forwarding multicast packets to all ports in a VLAN, the system extracts only the necessary forwarding paths by having switches forward packets only to specific next-hop switches that are part of the multicast distribution tree, eliminating waste on devices that don't need the packets
Solution Approach 2:
The patent introduces Layer 3 switches as intermediary devices that perform multicast routing functions. These L3 switches act as mediators between the multicast source and L2 switches, determining the correct forwarding paths and instructing L2 switches on where to forward packets, thereby preventing unnecessary flooding
2Reliability
If multicast packets are forwarded to all ports in a VLAN, then all devices can receive the packets, but network resource utilization deteriorates due to unnecessary transmissions
Solution Approach 1:
The patent implements dynamic multicast forwarding where L2 switches receive forwarding instructions from L3 switches based on real-time network conditions and multicast group membership. The forwarding behavior is not static but dynamically adjusted according to the distribution tree structure and device requests, optimizing network resource utilization while ensuring reliable delivery
3Device complexity
If Layer 2 switches forward multicast packets without selective routing, then implementation is simple, but bandwidth efficiency decreases due to flooding to irrelevant devices
Solution Approach 1:
The patent introduces Layer 3 switches as intermediary devices that perform the complex multicast routing calculations and path determination. L2 switches maintain simple forwarding logic by only executing instructions from L3 switches, thereby keeping L2 switch complexity low while achieving efficient selective forwarding without flooding
Solution Approach 2:
The patent segments the multicast forwarding function into two parts: L3 switches handle the complex routing decision-making and distribution tree management, while L2 switches handle simple packet forwarding based on instructions. This segmentation allows L2 switches to remain simple while achieving efficient selective forwarding
Data Source
AI summary
A network system includes a plurality of first communication apparatuses that perform multicast routing, and a plurality of second communication apparatuses configured to connect between the plurality of first communication apparatuses and forward a multicast packet from a port other than a receiving port. Each one of the plurality of second communication apparatuses includes a first memory configured to store the receiving port at which an entry request for a multicast group sent by one of the plurality of first communication apparatuses has been received as a forward port for multicast packets for that multicast group, and a forwarding unit configured to forward a multicast packet for the multicast group from the forward port among the ports of the second communication apparatus.