MPLS Ring Network Restoration Using ERP Pseudowires
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Solution Overview
Problem
Existing MPLS ring network restoration methods require a large number of Label Switched Paths (LSPs) and can result in traffic being doubled back, wasting bandwidth and overloading management systems, especially in the event of network link failures.
Innovation Solution
The method involves using Ethernet Ring Protocol (ERP) restoration messages encapsulated in pseudowires within LSPs to quickly detect and respond to network link failures, allowing for efficient rerouting without doubling back traffic, and utilizing fewer LSPs than traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four LSPs are set up for each traffic ingress/egress node pair (working LSP clockwise, working LSP anticlockwise, restoration LSP clockwise, restoration LSP anticlockwise), then network survivability is improved, but device complexity and management system load increase significantly
Solution Approach 1:
The patent merges the restoration functionality into the existing working LSPs by enabling bidirectional traffic flow. Instead of requiring separate restoration LSPs, the system utilizes the same LSP infrastructure for both working and restoration purposes, allowing traffic to dynamically switch directions based on failure conditions. This reduces the number of LSPs from four per node pair to just two per node pair.
Solution Approach 2:
The working LSPs are designed to serve multiple functions: they act as primary working paths in normal conditions and automatically serve as restoration paths when failures occur. The same LSP infrastructure is universally used for both protection and restoration, eliminating the need for dedicated restoration LSPs and reducing overall system complexity.
2Reliability
If traffic is doubled back or wrapped from network node adjacent to failure, then network connectivity is restored, but network bandwidth is wasted due to traffic traversing network section twice
Solution Approach 1:
The system dynamically adjusts traffic flow direction based on real-time network conditions and failure locations. When a failure is detected, traffic automatically reroutes through the alternative direction of the ring, utilizing dynamically selected paths rather than static wrapped paths. This dynamic adaptation allows traffic to take the most efficient route around the failure point without unnecessary doubling back.
3Reliability
If a large number of LSP labels are required for each ingress/egress node pair, then network survivability is improved, but management system load increases heavily
Solution Approach 1:
The patent combines the protection and restoration LSP label management into a single simplified label set. By using the same LSPs for both working and restoration functions, the system reduces the number of LSP labels that need to be managed, assigned, and tracked by the management system, thereby significantly reducing management overhead while maintaining full protection capability.
Data Source
Figure 1
Figure 2a~2b
Figure 3A
AI summary
According to the present invention, there is provided a method for restoring a MultiProtocol Label Switching (MPLS) ring network in the event of a network link failure. The MPLS ring network comprises a path for traffic around the ring comprising a plurality of sequential Label Switched Paths (LSPs). The method comprises, at a network node in the MPLS ring network: detecting a failure along a network link traversed by a first LSP having an end point at the network node; in response to the detecting, encapsulating an Ethernet Ring Protocol (ERP) restoration message in a restoration pseudowire; and transmitting the restoration pseudowire within a second LSP over a subsequent network link. The method also comprises, at a network node in the MPLS ring network: receiving a first LSP comprising a pseudowire; detecting that the pseudowire is a restoration pseudowire comprising an Ethernet Ring Protocol (ERP) restoration message; and in response to the detecting, processing the ERP restoration message. There is also provided a network node for an MPLS ring network, and an MPLS ring network.