VXLAN Switch Fabric Board Multicast Forwarding
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Solution Overview
Problem
Current VXLAN technologies face challenges in implementing efficient layer 3 multicast forwarding within VXLAN switches, particularly in identifying and processing multicast data packets to ensure proper routing and resource management without bandwidth wastage.
Innovation Solution
A method and structure for a VXLAN switch that includes a main board, I/O board, and fabric board, where the fabric board uses chips with forwarding and entry functions to cooperate with the I/O board in processing multicast data packets, removing VXLAN encapsulation, and performing layer 3 forwarding by identifying virtual network identifiers and MAC entries, and adding internal encapsulations to ensure correct routing across multiple I/O boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional VXLAN switching architecture is used for multicast forwarding, then device simplicity is maintained, but forwarding efficiency and wire-speed processing cannot be achieved
Solution Approach 1:
The patent segments the VXLAN switch into three functional boards: I/O board for packet reception and initial processing, fabric board for high-speed internal forwarding using dedicated forwarding chips, and main board for control and management. This segmentation enables each component to specialize in specific tasks, achieving wire-speed multicast forwarding while maintaining overall system manageability.
Solution Approach 2:
The patent introduces a new architectural dimension by adding the fabric board as an intermediate layer between I/O and main boards. This creates a multi-dimensional processing path: I/O board receives packets → fabric board performs high-speed forwarding based on VXLAN identifiers → main board handles control functions. This dimensional addition resolves the contradiction by providing dedicated high-speed forwarding paths without complicating the control plane.
2Reliability
If multicast data packets are forwarded without removing VXLAN encapsulation, then processing speed is maintained, but proper layer 3 routing and resource management cannot be performed
Solution Approach 1:
The I/O board performs preliminary actions by removing VXLAN encapsulation and extracting layer 3 headers before forwarding packets to the fabric board. This preliminary processing ensures that subsequent routing decisions can be made accurately based on exposed layer 3 information, while the fabric board's dedicated forwarding chips compensate for the time cost through high-speed processing.
Solution Approach 2:
The fabric board acts as an intermediary between the I/O board and external networks. It receives packets with removed VXLAN encapsulation, performs high-speed forwarding decisions based on layer 3 information, and forwards packets to appropriate destinations. This intermediary role enables both accurate routing (by having full packet visibility) and fast forwarding (by using dedicated forwarding hardware).
3Loss of information
If VXLAN encapsulation is removed for multicast forwarding, then layer 3 routing information becomes accessible, but additional processing steps are required
Solution Approach 1:
The I/O board extracts the VXLAN encapsulation layer from incoming packets, removing the outer UDP/TCP headers to expose the inner layer 3 IP headers. This extraction makes routing information accessible to the fabric board's forwarding chips, which can then make high-speed routing decisions based on visible layer 3 addresses without requiring complex encapsulation handling.
4Productivity
If multicast packets are forwarded to all I/O boards, then complete distribution is achieved, but bandwidth is wasted on unnecessary forwarding
Solution Approach 1:
The fabric board implements feedback mechanisms by tracking which I/O boards have already received specific multicast packets. When a multicast packet arrives, the fabric board checks its forwarding table to determine which I/O boards need the packet, and only forwards to those specific destinations. This feedback-based selective forwarding achieves complete distribution to all receiving boards while avoiding redundant bandwidth consumption on boards that have already received the packet.
Data Source
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AI summary
An I/O board of a VXLAN switch receives a multicast data packet having a VXLAN encapsulation, removes the VXLAN encapsulation, determines that layer 3 multicast forwarding is to be performed for the multicast data packet, and sends the multicast data packet to a fabric board of the VXLAN switch. The fabric board determines that layer 3 multicast forwarding is to be performed by the fabric board for the multicast data packet. When a multicast group member port corresponding to the multicast data packet is a VLAN port, the fabric board sends the multicast data packet to each I/O board on the VXLAN switch. Each I/O board sends the received multicast data packet to a VLAN according to a layer 3 multicast group entry used for forwarding the received multicast data packet. The layer 3 multicast group entry being included in a local layer 3 multicast group table.