Ethernet Loop Mitigation via VID-Based Reverse Path Forwarding
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Solution Overview
Problem
Existing mechanisms for mitigating loops in Ethernet networks are limited, leading to issues such as dropped frames and wasted network resources due to transient and steady-state loops.
Innovation Solution
The implementation of a reverse path forwarding check using Virtual Local Area Network Identifiers (VIDs) instead of source MAC addresses, which allows for efficient loop mitigation by performing ingress and egress checks using existing Ethernet lookup mechanisms, thereby preventing looped transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional loop mitigation mechanisms are used, then loops can be detected, but the number of lookups increases and network efficiency decreases
Solution Approach 1:
The patent combines the ingress check and egress check into a single unified lookup operation using the VID as the key. Instead of performing separate lookups for ingress filtering and egress port determination, the system merges these functions by storing both ingress enablement status and egress port information in a single database entry indexed by VID, thereby reducing lookup operations while maintaining loop detection capability
Solution Approach 2:
The VID database is designed to serve multiple functions simultaneously: it performs ingress filtering validation, determines egress ports for frame forwarding, and enables loop detection. By making this single database structure multi-functional, the patent eliminates the need for separate lookup mechanisms, improving network efficiency while preserving comprehensive loop mitigation
2Measurement precision
If multiple lookup operations are performed for frame forwarding, then forwarding accuracy is improved, but processing time increases
Solution Approach 1:
The system performs preliminary organization of forwarding information by pre-configuring the VID database with both ingress enablement status and egress port mappings before frame arrival. This preliminary action ensures that when a frame needs forwarding, all necessary information is already structured and accessible in a single lookup operation, eliminating the need for sequential lookups and reducing processing time while maintaining forwarding accuracy
Data Source
AI summary
A technique is provided for mitigating loops in Ethernet networks. A first port in an Ethernet device receives an Ethernet frame. The frame includes a source identifier, a destination identifier, and a Virtual Local Area Network Identifier (VLAN ID). According to various embodiments, the VLAN ID (VID) has the encoding of both a community group as well as a source bridge ID. A VID database is accessed using the destination identifier and the VID to determine whether the first port has ingress enabled. A filtering database is accessed to determine an egress port for forwarding the Ethernet frame.