Supplemental Bridge Domain Interface for Inter-Subnet Multicast Forwarding
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Solution Overview
Problem
In Ethernet virtual private network (EVPN) ERB overlay fabrics, maintaining tables for inter-subnet multicast capabilities and associations across a large number of leaf devices and VLANs becomes resource-intensive, impacting traffic forwarding performance.
Innovation Solution
Implementing a supplemental bridge domain (SBD) interface in provider edge (PE) network devices allows them to forward inter-subnet multicast traffic efficiently, reducing the need for maintaining extensive tables by only tracking local and remote PE network devices, thereby conserving computing, memory, and communication resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extensive tables are maintained to track inter-subnet multicast capabilities and associations across all leaf devices and VLANs, then complete traffic forwarding control is achieved, but computing, memory, and processing resources are consumed excessively
Solution Approach 1:
The patent extracts the essential forwarding function from the comprehensive table-based control mechanism. By using SBD interfaces, the system maintains only minimal local state information (remote PE device addresses) rather than extensive tables tracking all leaf devices and VLANs, thereby reducing resource consumption while preserving forwarding capability
Solution Approach 2:
The SBD interface acts as an intermediary mechanism that mediates between the need for comprehensive traffic control and the desire to reduce table maintenance overhead. It provides a simplified interface for forwarding decisions without requiring full knowledge of the entire network topology
2Reliability
If comprehensive tables are maintained to track all leaf devices and VLANs, then complete multicast traffic control is achieved, but device complexity increases
Solution Approach 1:
The patent removes the complex table maintenance functionality by extracting only the essential forwarding action. The SBD interface handles traffic forwarding by simply copying packets to remote PE devices without requiring complex table lookups or maintenance operations
Solution Approach 2:
Instead of maintaining comprehensive tables, the system uses copying mechanisms where the SBD interface creates simplified representations (copies) of necessary forwarding information locally, eliminating the need for full topology tables while preserving forwarding decisions
3Reliability
If extensive tables are maintained for inter-subnet multicast, then accurate traffic forwarding is achieved, but processing performance is impacted
Solution Approach 1:
The patent extracts the critical forwarding function from resource-intensive table processing. The SBD interface performs forwarding by directly copying packets to remote PE devices based on minimal local state, eliminating the processing overhead associated with comprehensive table lookups while maintaining forwarding accuracy
Data Source
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AI summary
In some implementations, a first network device that hosts a bridge domain (BD) may receive inter-subnet multicast traffic associated with the BD. The BD may forward, using a supplemental bridge domain (SBD) interface of the first network device, and via an SBD, a first copy of the inter-subnet multicast traffic to a second network device that hosts the BD. The first network device may forward, using the SBD interface and via the SBD, a second copy of the inter-subnet multicast traffic to a third network device that does not host the BD. The first network device may forward, using an integrated routing and bridging (IRB) interface of the first network device associated with the BD, a third copy of the inter-subnet multicast traffic to a fourth network device that hosts the BD (e.g., when the fourth network device is a multihoming peer of the first network device).