Automated VCCV Tracing for Multi-Segment Pseudo-Wire Connectivity
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Solution Overview
Problem
Current methods lack an effective way to easily verify end-to-end connectivity and pinpoint the point of failure in multi-segment pseudo-wire (MS-PW) networks, as the control plane of the ingress node does not have access to necessary information for formatting VCCV echo requests, making manual verification time-consuming and impractical, especially when MS-PWs span different service providers.
Innovation Solution
A method involving automated VCCV tracing, where each target node responds with an echo reply containing a FEC128 sub-TLV and return codes, allowing the originating node to compose subsequent echo requests and traverse the MS-PW segments dynamically, facilitating end-to-end connectivity verification with a single operational command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual segment-by-segment verification is used, then connectivity of each segment can be verified, but the verification process becomes time-consuming and impractical
Solution Approach 1:
The patent divides the multi-segment pseudo-wire verification into individual segment echo requests. Each echo request targets a specific segment and receives an echo reply, allowing systematic verification of each segment while automating the process. The control plane formats and sends targeted echo requests for each segment, transforming manual verification into an automated sequence of segment-level checks.
Solution Approach 2:
The control plane pre-formats echo requests with necessary segment information before transmission. By preparing the verification messages in advance with embedded segment identifiers and parameters, the system eliminates real-time formatting delays and enables rapid automated verification of multiple segments without manual intervention during the actual testing phase.
2Productivity
If automated VCCV tracing is implemented, then verification efficiency is improved, but the control plane lacks access to necessary information for formatting echo requests
Solution Approach 1:
The patent introduces an intermediary mechanism where the control plane obtains segment information from the data plane or network management system. This intermediary information exchange allows the control plane to access necessary segment identifiers and parameters through standardized interfaces, enabling automated echo request formatting without direct access to internal data plane structures.
Solution Approach 2:
The control plane is designed with multi-functional capabilities to both format echo requests and process echo replies using common verification logic. This universal verification module can handle multiple segments and different pseudo-wire types, reducing information loss by reusing the same control structures and data formats across different verification scenarios.
3Reliability
If end-to-end connectivity verification is performed, then complete path validation is achieved, but the complexity of multi-segment information management increases
Solution Approach 1:
The patent implements nested verification where echo requests and replies are structured with hierarchical segment information. Each echo reply contains embedded segment identifiers that nest within the overall verification context, allowing the control plane to track multiple segments through nested data structures. This nesting organizes complex multi-segment information in a manageable hierarchical format.
Solution Approach 2:
The system uses feedback mechanisms where each echo reply provides information about segment connectivity status and next-hop segment identifiers. This feedback loop allows the control plane to dynamically adjust subsequent echo requests based on previous results, automatically managing the complexity of multi-segment verification by using feedback from each segment to determine the next verification target.
Data Source
AI summary
A method for testing connectivity of a multi-segment pseudo-wire in a packet switched network, the method comprising: (a) sending an echo request message from a first provider edge device to a second provider edge device for a first segment of the multi-segment pseudo-wire between the first provider edge device and the second provider edge device; and, (b) receiving an echo reply message from the second provider edge device in response to the echo request message, the echo reply message: confirming connectivity of the first segment; indicating whether there is a second segment in the multi-segment pseudo-wire between the second provider edge device and a third provider edge device; and, if there is a second segment, including information pertaining to the second segment.