PESL and RL2 Constructs for Fast Layer 2 Overlay Convergence
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Solution Overview
Problem
Current Layer 2 overlay networks face challenges in supporting multiple paths to reach active destinations, leading to synchronization and convergence delays due to the need for updating routes for each destination, especially in scenarios with multi-homing and failure detection mechanisms that do not scale well with existing technologies.
Innovation Solution
The introduction of Provider Edge Service Label (PESL) and Remote Layer 2 (RL2) forwarding constructs enables fast control path and data path convergence by identifying primary and alternate paths, allowing updates to the data plane without modifying forwarding table entries for each destination, thereby enabling multi-way forwarding and reducing convergence times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing reroute mechanisms update routes to each L2 destination individually, then route accuracy is improved, but convergence time increases significantly
Solution Approach 1:
The patent merges the routing information for multiple L2 destinations into a single aggregated route entry. Instead of maintaining separate forwarding table entries for each L2 destination, the invention consolidates them under a common route identifier, allowing simultaneous updates for all destinations when a network event occurs, thus reducing convergence time while maintaining routing accuracy
Solution Approach 2:
The patent creates a universal route representation that serves multiple L2 destinations simultaneously. The aggregated route entry functions as a multi-functional identifier that represents a group of destinations, enabling a single update operation to affect all associated destinations and eliminate the need for individual updates
2Reliability
If multiple paths are supported for multi-homed destinations, then network reliability is improved, but control plane complexity increases
Solution Approach 1:
The patent introduces an intermediary aggregated route entry that mediates between the control plane and multiple L2 destinations. This intermediary abstraction simplifies the control plane by providing a single point of management for multiple paths, while still enabling support for multi-homed destinations and their associated reliability requirements
3Manufacturing precision
If forwarding table entries are updated for each L2 destination, then forwarding precision is improved, but synchronization delays increase
Solution Approach 1:
The patent performs preliminary aggregation of forwarding information into a consolidated route entry before network events occur. This preliminary action prepares the forwarding structure in advance, so that when a network event requires updates, all necessary forwarding precision can be applied simultaneously through a single update operation, eliminating sequential synchronization delays
Data Source
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AI summary
Methods and apparatuses for fast convergence in Layer 2 overlay network are described. Forwarding of Layer 2 (L2) traffic addressed to one or more remote L2 destinations is performed according to a remote L2 (RL2) instance, where the RL2 instance identifies a primary path for forwarding the traffic towards the remote L2 destinations, and a provider edge service label (PESL) instance associated with a broadcast domain including one or more network devices for forwarding the L2 traffic towards the L2 destination, and where the PESL instance is identified with a unique immutable PESL instance label. In response to a network event, an update of the RL2 instance is performed. The update results in an update of a data plane for forwarding the L2 traffic without necessitating an update of forwarding table entries for each one of the one or more remote L2 destination.