Pseudowire Redundancy via Domain Segmentation
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Solution Overview
Problem
Current solutions for Multi-Segment Pseudowire (MS-PW) resiliency, such as end-to-end path protection, face limitations including cross-domain switchover issues, slower protection switching, and multiple switching behaviors across different PSN domains, especially when failures occur in AC links or PW segments, leading to inefficient network operations.
Innovation Solution
A network node architecture that forms redundancy groups across domains, with interfaces configured for selective forwarding and role-based active/standby status determination, allowing for localized failure management within domains and flexible deployment across multiple operators, utilizing Master-Slave modes and Distributed Resilient Network Interconnect (DRNI) technology for efficient traffic routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If end-to-end path protection is deployed in T-PE nodes, then PW resiliency is provided, but protection switching speed is slow due to long notification paths and T-PE negotiation
Solution Approach 1:
The patent divides the end-to-end PW protection into separate segment-level protections at each S-PE node. Each S-PE independently manages its own PW segments with local redundancy groups, eliminating the need for end-to-end notification paths and T-PE negotiations. This segmentation enables faster local switching while maintaining overall PW resiliency.
Solution Approach 2:
The patent pre-configures redundancy groups and standby PW segments at each S-PE node before failures occur. When a failure is detected, the pre-established redundancy mechanisms enable immediate local switching without requiring real-time negotiation or path establishment, thus accelerating protection switching speed.
2Reliability
If one PW failure within one PSN triggers switchover behavior within other PSNs, then end-to-end protection is activated, but cross-domain interference occurs which is not preferred when administrated by different operators
Solution Approach 1:
The patent implements domain-independent redundancy groups at each S-PE, where protection switching is localized to individual domains. Each domain's redundancy group operates independently, so a failure in one PSN does not trigger switchover in other PSNs, eliminating cross-domain interference while maintaining protection within each domain.
Solution Approach 2:
The patent applies different protection characteristics to different domains by establishing local redundancy groups at each S-PE. Each domain can be administered independently with its own failure detection and switching behavior, allowing operators to control protection scope locally rather than forcing uniform end-to-end protection across all domains.
3Reliability
If one failure in AC link triggers multiple switching behaviors in PSN domains, then comprehensive protection is provided, but network operation efficiency decreases due to multiple unnecessary switchings
Solution Approach 1:
The patent segments the protection scope by establishing redundancy groups that associate AC links with specific PW segments at the same S-PE. When an AC link fails, only the affected PW segments within that local redundancy group trigger switching, rather than triggering multiple switchings across different PSN domains, thus improving network operation efficiency.
4Speed
If S-PE provides PW redundancy, then protection switching speed increases and T-PE burden is reduced, but device complexity increases at S-PE nodes
Solution Approach 1:
The patent pre-configures redundancy groups and standby PW segments at S-PE nodes before failures occur. This preliminary setup enables fast local switching without requiring complex real-time negotiation or path computation, as the switching decisions are based on pre-established redundancy relationships and local failure detection.
Solution Approach 2:
The S-PE nodes autonomously detect failures within their own domains and independently execute switching decisions using locally configured redundancy groups. This self-service capability eliminates the need for complex inter-domain coordination or centralized control, managing the increased complexity through decentralized autonomous operation.
Data Source
AI summary
Methods and apparatuses for PW redundancy have been provided. A network node across a first domain and a second domain is disclosed. In each domain, the network node and at least one second network node form a first redundancy group (RG) in the first domain and a second RG in the second domain. The network node comprises a first set of interfaces facing the first domain, a second set of interfaces facing the second domain, and a forwarder. In the first set, at least a first and a second interfaces are configured for connecting with PW segments within the first domain; in the second set, at least a first and a second interfaces are configured for connecting with PW segments within the second domain. A third interface in the first set and a third interface in the second set are configured for transferring traffic between the network node and the at least one second network node and between the first domain and the second domain. The forwarder is configured for forwarding traffic selectively between one interface of the first set and one interface of the second set.