Shared Path Recovery Signaling in GMPLS Networks
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Solution Overview
Problem
In GMPLS networks, shared recovery paths can lead to significant traffic loss due to delayed notification of resource unavailability, as existing methods do not efficiently manage shared resources between multiple Label Switched Paths (LSPs), particularly in photonic networks where a single LSP can carry high traffic volumes like 40Gbs.
Innovation Solution
A method is introduced where a first node in a connection-oriented network allocates resources for a recovery path shared by multiple LSPs and stores associations to notify ingress nodes when these resources are used, utilizing RSVP-TE Notify messages for quick signaling, avoiding the need for new message types or additional protocols, thus minimizing unnecessary resource activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If link-state routing protocol is used to propagate resource unavailability information, then information can be propagated across the network, but the notification is delayed causing heavy traffic loss
Solution Approach 1:
The patent applies preliminary action by pre-establishing notification relationships between nodes on shared recovery paths and ingress nodes before failures occur. When resources are allocated on a recovery path, the system proactively notifies the ingress node in advance, so that when a failure occurs and the protection path is needed, the ingress node already knows the resources are unavailable and can switch to an alternative path immediately, avoiding traffic loss.
Solution Approach 2:
The patent implements feedback by creating a direct notification mechanism where nodes on recovery paths provide real-time status information back to ingress nodes. When a node allocates or uses resources on a shared recovery path, it sends a notification message back to the associated ingress node, creating a closed-loop feedback system that enables rapid response to resource changes without waiting for periodic link-state updates.
2Reliability
If protection capacity is pre-reserved for multiple LSPs sharing common resources, then recovery capability is improved, but resource availability conflicts occur when multiple paths need simultaneous protection
Solution Approach 1:
The patent applies dynamics by making the protection capability adaptive rather than static. Instead of rigidly reserving resources for multiple LSPs simultaneously, the system dynamically allocates and notifies ingress nodes about shared resource usage. This allows the network to adapt resource allocation based on actual needs and failure scenarios, enabling one protection path to use shared resources while notifying other ingress nodes so they can select alternative paths when needed.
3Speed
If RSVP-TE Notify messages are used for resource allocation signaling, then signaling speed is improved, but compatibility with existing protocols must be maintained
Solution Approach 1:
The patent applies universality by making the existing RSVP-TE Notify message serve multiple functions. The Notify message is traditionally used for error notifications, but this patent extends it to also carry resource allocation information and protection path status updates. By embedding additional information elements within the existing message structure, the system achieves fast signaling without requiring new message types, maintaining protocol compatibility while enabling new functionality.
Data Source
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AI summary
A connection-oriented network (6) has a first working path (W1) and a second working path (W2). A node (E) receives signalling to allocate resources for a part of a recovery path (R1) for the first working path (W1). The resources are shared by the recovery path (R1) for the first working path and a recovery path (R2a) for the second working path (W2). The node (E) stores an association between the shared resources and a node (A) on the first working path, identified in the signalling, which should be notified when the shared resources are used by the recovery path (R2a) for the second working path (W2). An RSVP-TE <NOTIFY_REQUEST> object in the signalling carries an address of the node to be notified. The node (E) sends an RSVP-TE Notify message to a node (A) on the first working path (W1) which indicates that the shared resources are in use.