OAM LSP for Fast Reroute of Protected Label Switched Paths
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Solution Overview
Problem
Conventional computer networks using link state protocols like OSPF and IS-IS take a long time to adapt to node and link failures, leading to significant delays in rerouting traffic, which affects performance for sensitive applications like VoIP and multimedia due to large convergence times.
Innovation Solution
Implementing a dedicated Operations, Administration, and Management (OAM) Label Switched Path (LSP) for monitoring the primary path between a Point of Local Repair (PLR) and a Merge Point (MP), allowing for dynamic signaling and fast rerouting of data traffic to a backup path upon failure, using extensions to RSVP-TE protocol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional link state protocols (OSPF, IS-IS) are used for routing, then routing information can be exchanged and paths can be established, but convergence time is large causing significant delays in traffic rerouting
Solution Approach 1:
The patent establishes a dedicated OAM LSP before any failure occurs to monitor the primary path's connectivity. This preliminary monitoring action enables immediate detection of failures without waiting for conventional routing protocols to detect and respond to topology changes, thereby reducing convergence time and rerouting delay.
Solution Approach 2:
The patent introduces a dedicated OAM LSP as an intermediary monitoring channel between the PLR and MP. This intermediary path carries OAM messages that independently monitor the primary path's status, providing fast failure detection separate from the data traffic path and conventional routing protocols.
2Loss of time
If a dedicated OAM LSP is established for path monitoring, then failure detection speed is improved, but device complexity increases
Solution Approach 1:
The patent extends RSVP-TE protocol functionality to serve dual purposes: traditional data traffic routing and dedicated OAM message monitoring. By making RSVP-TE multi-functional, the system avoids adding entirely new protocol layers, thereby limiting the increase in device complexity while achieving fast failure detection.
Solution Approach 2:
The patent creates a dedicated OAM LSP that is a separate but parallel copy of the data LSP structure. This copying approach allows independent monitoring functionality without fundamentally changing the existing LSP architecture, enabling fast failure detection while managing complexity through structured duplication rather than radical redesign.
3Productivity
If RSVP-TE protocol is extended for dynamic OAM LSP signaling, then fast rerouting capability is enabled, but protocol complexity increases
Solution Approach 1:
The patent merges OAM monitoring functionality with the existing RSVP-TE protocol framework. By combining these functions within the same protocol structure, the system achieves fast rerouting capability without requiring separate independent protocols, thereby limiting the increase in overall protocol complexity.
Solution Approach 2:
The patent introduces dynamic signaling capabilities to RSVP-TE, allowing the OAM LSP to be established, modified, and terminated automatically based on network conditions. This dynamic approach enables fast rerouting while managing protocol complexity through automated control rather than static configuration.
Data Source
AI summary
In response to receiving a reply message for reserving bandwidth along a primary path for a first label switched path (LSP) for carrying data traffic from an ingress network device to an egress network device, a point of local repair (PLR) network device establishes a second LSP from the PLR to a merge point (MP) network device along a subset of the primary path. The second LSP is dedicated to carrying operations, administration and management (OAM) messages to verify connectivity of the subset of the primary path, and is not used for sending data traffic. The PLR sends an OAM message to verify connectivity of at least one protected resource along the subset of the primary path to a next hop along the second LSP, wherein the OAM message is encapsulated by a second label associated with the second LSP.