Pseudo Wire Control Word Negotiation Inconsistency
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Solution Overview
Problem
The existing pseudo wire control word negotiation process often results in inconsistencies between control word configurations and expected negotiation results, leading to ineffective support for control words in pseudo wire networks.
Innovation Solution
A method and system where a Provider Edge acquires and determines a control word value by sending label request and mapping messages to an opposite terminal, ensuring accurate negotiation by considering both locally configured and negotiated values, applicable to single and multiple segment pseudo wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the C-Bit in the label mapping message is set to 0 to indicate no control word support, then the negotiation process is simple and fast, but the configuration consistency between local and remote terminals cannot be ensured
Solution Approach 1:
The patent introduces a feedback mechanism where the local terminal re-sends the label mapping message with updated C-Bit value after detecting configuration consistency. This feedback loop ensures that the remote terminal receives accurate control word capability information, resolving the contradiction between fast negotiation and configuration consistency by allowing a second negotiation attempt when inconsistency is detected.
Solution Approach 2:
The patent performs preliminary detection of configuration consistency between local and remote terminals before finalizing the negotiation result. By checking whether both terminals have consistent control word configurations prior to completing the negotiation, the system can prevent inconsistent states from being established, thus maintaining reliability without significantly impacting negotiation speed.
2Loss of time
If the control word capability is negotiated based on the first received label mapping message, then the negotiation process is quick, but the negotiation result may be inconsistent with the actual configuration
Solution Approach 1:
The patent implements a feedback mechanism that detects configuration consistency and triggers re-negotiation when inconsistency is found. The local terminal compares its configuration with the negotiated result and, upon detecting mismatch, re-sends the label mapping message with corrected C-Bit value, ensuring accurate negotiation results while minimizing time loss through selective re-negotiation.
Solution Approach 2:
The patent makes the negotiation process dynamic by allowing it to be extended or terminated based on configuration consistency detection. The system can quickly complete negotiation when configurations are consistent, but automatically extends the process to include re-negotiation when inconsistency is detected, thus adapting the negotiation time and accuracy to the actual network state.
3Reliability
If the label mapping message is re-sent after configuration change, then the control word capability is updated accurately, but additional message exchanges increase negotiation overhead
Solution Approach 1:
The patent uses feedback-driven re-sending of label mapping messages. Instead of re-sending messages unconditionally, the system first detects whether configuration consistency exists, and only triggers re-sending when inconsistency is detected. This feedback mechanism ensures accurate capability updates while avoiding unnecessary message exchanges and associated overhead.
Solution Approach 2:
The patent changes the C-Bit parameter in the label mapping message based on detected configuration consistency. When inconsistency is found, the system modifies the C-Bit value to reflect the actual control word capability and re-sends the message, ensuring accurate capability representation without requiring complete re-negotiation of all parameters, thus reducing message exchange complexity.
Data Source
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AI summary
A method and system for implementing a pseudo wire control word capability negotiation are disclosed in the present document. The method includes: when modifying a local control word value, a Provider Edge (PE) acquiring a control word value configured or negotiated locally by an opposite terminal provider edge by sending label request message and receiving label mapping message, and according to the local control word value and the acquired control word value, the provider edge determining a control word value negotiated with respect to a pseudo wire. In the present document, the problem of inconsistency between the control word configurations and the expected negotiation results existing in certain specific scenarios is solved, which enhances the negotiation performance. The technical scheme of the present document is easy to implement, it makes slight modifications on the existing protocol, and it is applicable to a single segment pseudo wire scenario and a multiple segment pseudo wire scenario, which has lower implementation costs.