EVPN Label Sharing with Unique Service Instance Identifiers
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Solution Overview
Problem
In Ethernet virtual private networks (EVPN) using flexible cross-connect services, the lack of individual identification for each access circuit (AC) within a multiplexed service instance prevents accurate signaling of AC unavailability, leading to inefficient resource usage and load balancing issues, as the Ethernet A-D per EVI route cannot be withdrawn when a single AC fails, causing continued traffic transmission and potential discarding of data.
Innovation Solution
A provider edge (PE) device advertises multiple Ethernet A-D per EVI routes, each with a unique Service Instance Identifier (SIID) for a single AC and a shared MPLS label, allowing for the signaling of AC unavailability while conserving label usage by using the same label across routes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single shared label is used for multiple access circuits in an EVPN instance, then label usage is conserved and network scalability is improved, but individual identification of each access circuit is lost, preventing accurate signaling of AC unavailability
Solution Approach 1:
The patent segments the identification mechanism by introducing Service Instance Identifiers (SIIDs) that are embedded within route advertisements. Each SIID uniquely identifies a specific access circuit (AC) within an EVPN instance, allowing individual AC status to be tracked and signaled independently while still using a shared MPLS label for the overall EVPN instance. This segmentation resolves the contradiction by providing granular identification without requiring separate labels for each AC.
2Reliability
If the Ethernet A-D per EVI route is withdrawn when a single AC fails, then accurate signaling of AC unavailability is achieved, but resource usage becomes inefficient and load balancing issues occur
Solution Approach 1:
Instead of withdrawing the entire Ethernet A-D per EVI route when a single AC fails (excessive action), the patent applies partial action by withdrawing only the specific SIID-associated route advertisement while maintaining the overall EVPN instance and other ACs. This allows selective signaling of AC unavailability without disrupting the entire network instance or causing unnecessary resource reconfiguration, thus resolving the contradiction between reliable signaling and efficient resource usage.
3Reliability
If multiple labels are assigned to each access circuit for individual identification, then accurate AC status signaling is enabled, but label usage increases and network scalability decreases
Solution Approach 1:
The patent makes the SIID mechanism universal by embedding it within the existing EVPN route advertisement structure. The SIID serves multiple functions: it identifies the access circuit, enables individual AC status signaling, and maintains compatibility with the shared MPLS label structure. This multi-functionality allows accurate AC status signaling without requiring separate labels for each AC, thus preserving network scalability while achieving reliable AC status tracking.
Data Source
AI summary
A provider edge (PE) device may determine a first identifier, corresponding to a first connection for a first service, and a second identifier, corresponding to a second connection for a second service, where the first connection is between a first customer edge (CE) device and the PE device, and the second connection is between a second CE device and the PE device. The PE device may advertise a first route, associated with the first service, based on the first identifier and a label corresponding to a network instance. The PE device may advertise a second route, associated with the second service, based on the second identifier and the label. The PE device may determine that the first connection is unavailable, and withdraw advertisement of the first route, while maintaining advertisement of the second route, to indicate, to a remote PE device, that the first connection is unavailable.