VXLAN Switch Fabric Board Multicast Forwarding
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Solution Overview
Problem
Current VXLAN technologies face challenges in implementing efficient layer 3 gateway functions for multicast data packet forwarding between VLANs and VXLANs, particularly in ensuring wire-speed forwarding without bandwidth wastage.
Innovation Solution
A VXLAN switch with a fabric board equipped with forwarding and entry functions, cooperating with the I/O board to perform layer 3 multicast forwarding, involves internal encapsulations and decapsulations to modify MAC addresses and determine egress ports, enabling the forwarding of multicast data packets from VLANs to VXLANs through a gateway VXLAN switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If layer 3 gateway function is implemented for multicast data packet forwarding between VLANs and VXLANs, then routing capability is improved, but device complexity increases
Solution Approach 1:
The VXLAN switch is divided into functional modules: I/O board for packet reception and transmission, fabric board for internal forwarding and MAC address modification, and main board for control. This segmentation allows layer 3 gateway functionality to be implemented through coordinated operations of specific boards rather than requiring complete system redesign.
Solution Approach 2:
The fabric board acts as an intermediary between the I/O board and the main board, performing critical layer 3 gateway functions including modifying source MAC addresses to gateway MAC addresses and determining egress ports based on destination MAC addresses. This intermediary role simplifies the overall architecture by centralizing complex forwarding logic.
2Speed
If wire-speed forwarding is achieved for multicast data packets, then forwarding speed is improved, but bandwidth efficiency may deteriorate due to internal encapsulations
Solution Approach 1:
The fabric board pre-modifies the source MAC address to the gateway MAC address before packets are transmitted through the VXLAN tunnel. This preliminary action ensures that receiving switches can immediately forward packets without additional MAC address lookups or modifications, maintaining wire-speed forwarding while avoiding redundant processing that would waste bandwidth.
Solution Approach 2:
The patent replaces traditional layer 2 switching mechanisms with layer 3 routing mechanisms implemented at the fabric board level. By substituting MAC address learning and forwarding with IP-based routing and MAC address modification, the system achieves wire-speed multicast forwarding without the bandwidth overhead associated with traditional encapsulation methods.
3Measurement precision
If multicast group member ports are identified and processed, then forwarding accuracy is improved, but processing time increases
Solution Approach 1:
The fabric board maintains pre-computed forwarding information that maps destination MAC addresses to egress ports and VXLAN tunnel endpoints. When a multicast packet arrives, the fabric board performs a simple table lookup rather than complex path computation, achieving both high forwarding accuracy for multicast group members and minimal processing time.
Solution Approach 2:
The forwarding system uses self-service mechanisms where the fabric board autonomously determines egress ports and modifies MAC addresses based on pre-configured forwarding tables and real-time multicast group membership information. This self-service approach eliminates the need for complex inter-board communication and centralized control for each packet forwarding decision.
Data Source
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AI summary
An I/O board of a VXLAN switch receives a multicast data packet from a VLAN, and sends the multicast data packet to the fabric board of the VXLAN switch when at least one multicast group member port corresponding to the multicast data packet is a first virtual port. The fabric board determines that layer 3 multicast forwarding is to be performed by the fabric board. When a multicast group member port corresponding to the multicast data packet is a VXLAN tunnel port, the fabric board modifies a source MAC address of the multicast data packet, and sends the modified multicast data packet to an I/O board corresponding to the multicast group member port on the VXLAN switch. The I/O board corresponding to the multicast group member port adds a VXLAN encapsulation to the multicast data packet and forwards the multicast data packet having the VXLAN encapsulation to a VXLAN.