MPLS Pseudo-Wire Resource Locking via Label Withdraw Feedback
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Solution Overview
Problem
In MPLS networks, the inefficient resource allocation during pseudo-wire connection establishment leads to situations where one switch reserves resources while the other fails to, resulting in locked resources that cannot be reused for other connections, especially after network failures or resource contention.
Innovation Solution
A method where an MPLS switch sends a label mapping message to request a pseudo-wire connection, reserves resources, and if the other switch lacks resources, it sends a label withdraw message to release those resources, optimizing resource allocation by freeing resources at the far end when local reservation fails, allowing for re-attempts when resources become available.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If one switch reserves resources for a pseudo-wire connection while the other switch fails to reserve resources, then the first switch holds locked resources, but this prevents resource reuse for other connections and increases resource allocation inefficiency
Solution Approach 1:
The patent implements a feedback mechanism where the second switch sends a label withdraw message back to the first switch when resource reservation fails. This feedback loop allows the first switch to release locked resources, enabling efficient resource allocation and preventing resource waste.
Solution Approach 2:
The patent applies the discarding and recovering principle by allowing the first switch to release (discard) locked resources when the second switch cannot complete the pseudo-wire establishment. These resources are then recovered and made available for other connections, improving overall resource utilization efficiency.
2Ease of manufacture
If resources are reserved for pseudo-wire connections without checking availability at both ends, then connection establishment is simplified, but resource contention and locked resources increase
Solution Approach 1:
The patent applies preliminary action by having the first switch reserve resources before receiving confirmation from the second switch. However, it combines this with a verification step where the second switch confirms resource availability and sends a label mapping message, ensuring both ends have resources before the connection is fully established.
Solution Approach 2:
The patent uses feedback from the second switch's label mapping message to verify resource availability before completing the connection establishment. This feedback mechanism ensures both switches have sufficient resources, preventing resource contention and locked resources while maintaining connection establishment simplicity.
3Ease of operation
If label mapping messages are sent to request pseudo-wire connections, then connection establishment is initiated, but signaling overhead increases when resources are insufficient
Solution Approach 1:
The patent implements feedback through label mapping messages that contain resource availability information from the second switch. This feedback allows the first switch to make informed decisions about resource reservation, reducing unnecessary signaling when resources are insufficient and minimizing overall signaling overhead.
Solution Approach 2:
The patent applies partial action by having the first switch reserve resources preliminarily and then verify with the second switch's label mapping message before full connection establishment. This partial verification approach reduces excessive signaling by avoiding complete connection setup attempts when resources are clearly insufficient.
Data Source
AI summary
A method for establishing a pseudo-wire connection between first and second switches in a packet switched network, the method comprising: sending a label mapping message to the second switch requesting that the pseudo-wire connection be established with the first switch; reserving resources for the pseudo-wire connection at the first switch; receiving a label withdraw message from the second switch if the second switch has insufficient resources for the pseudo-wire connection and, in response to the label withdraw message, releasing the resources for the pseudo-wire connection at the first switch; and, activating the pseudo-wire connection if the second switch has sufficient resources for the pseudo-wire connection, thereby optimizing resources for establishing pseudo -wire connections of each of the first and second switches.