Layer Two MAC Rerouting via Event Identifier Comparison
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Solution Overview
Problem
Existing mechanisms for addressing port failures in layer two networks are slow and resource-intensive, leading to packet loss due to the reliance on outdated forwarding information in MAC address forwarding tables.
Innovation Solution
Implementing a method that uses a Spanning Tree Table with timestamps and event identifiers to compare and update forwarding paths, allowing linecards to redirect packets to alternate paths upon detecting events such as port failures, thereby reducing packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MAC address forwarding table is flushed to update forwarding information after a port failure, then the forwarding information becomes accurate, but the packet forwarding speed decreases and control plane resources are consumed
Solution Approach 1:
The patent segments the forwarding information into two parts: the MAC address forwarding table in the data plane (linecard) and the Spanning Tree Table in the control plane. The Spanning Tree Table stores event identifiers that indicate topology changes, while the MAC address forwarding table continues to use existing entries without flushing. This segmentation allows the data plane to operate independently at high speed while the control plane maintains accurate topology information.
Solution Approach 2:
The Spanning Tree Table acts as an intermediary between the control plane and data plane. It stores event identifiers that mediate the synchronization between topology changes and forwarding decisions. The linecard compares the event identifier from the Spanning Tree Table with its own stored identifier to determine if rerouting is needed, without requiring control plane intervention or MAC table flushing.
2Reliability
If the control plane resources are used to flush MAC address forwarding tables, then forwarding information is updated, but the control plane performance and network throughput decrease
Solution Approach 1:
The linecard performs self-service by autonomously comparing its stored event identifier with the current event identifier from the Spanning Tree Table. When a mismatch is detected, the linecard automatically reroutes packets without requiring control plane resources for MAC table flushing. This eliminates the need for control plane intervention in routine topology change handling.
Solution Approach 2:
The event identifier is pre-stored in the linecard's memory along with the MAC address forwarding table. This preliminary action allows the linecard to immediately detect topology changes by comparing identifiers without needing to query the control plane or flush tables, enabling fast autonomous rerouting decisions.
3Productivity
If the MAC address forwarding table is not updated after a port failure, then packet forwarding speed is maintained, but packets are forwarded to disabled ports causing loss
Solution Approach 1:
The patent replaces the mechanical system of flushing and rewriting MAC address forwarding tables with an identifier comparison mechanism. The linecard substitutes the need for table updates by comparing event identifiers, allowing it to detect topology changes and reroute packets without modifying the MAC address forwarding table structure or consuming resources for table maintenance.
Data Source
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AI summary
A method may include receiving a packet including a destination address, identifying a destination address entry based on the destination address, the destination address entry including an address identifier, comparing the address identifier to an event identifier, determining whether an event occurred based on the comparison, and forwarding the packet on an alternate path if it is determined that the event occurred.