Backup Tunnel Construction for Fast Reroute in Communications Networks
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Solution Overview
Problem
In communications networks, existing fast reroute techniques require time to identify and construct backup tunnels after a failure, potentially causing packet loss due to the need for network convergence and the lack of immediate information on which neighbor nodes to avoid in the backup path.
Innovation Solution
A method and apparatus that identify a destination for which a primary path is defined, transmit a request message with an 'avoid list' and 'request cost' to a neighbor node for routing information, and build a backup tunnel using distance vector routing protocols like EIGRP, which allows for rapid rerouting without waiting for network topology advertisements or constructing a full map.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fast reroute techniques are implemented to enable rapid recovery from network failures, then reliability is improved, but device complexity increases due to the need to compute and maintain backup tunnels
Solution Approach 1:
The patent applies preliminary action by pre-computing backup paths and storing them in a backup path database before failures occur. When a failure is detected, the system immediately retrieves pre-computed backup paths from the database rather than computing new paths in real-time, enabling rapid recovery while reducing the computational burden during failure events.
Solution Approach 2:
The patent uses copying by creating and storing backup path copies in a database. These backup paths are replicated versions of the network topology that can be quickly retrieved and used for rerouting without requiring complex real-time computations. The backup paths are copied and stored in advance, allowing fast retrieval when needed.
2Speed
If backup paths are pre-computed and stored in a database for fast reroute, then speed of rerouting is improved, but loss of information increases due to potential staleness of topology data
Solution Approach 1:
The patent implements feedback mechanisms where the system continuously monitors network topology changes and updates the backup path database accordingly. When topology changes are detected through routing protocol advertisements or failure notifications, the system refreshes the backup path information to ensure it remains current, thus preventing information staleness while maintaining fast rerouting capability.
Solution Approach 2:
The patent applies dynamics by making the backup path database updateable and adaptive. Rather than static pre-computed paths, the system dynamically updates backup paths based on current network conditions and topology changes. This allows the backup information to remain fresh and accurate while still enabling rapid retrieval and rerouting when failures occur.
Data Source
AI summary
In one embodiment, a method includes identifying at a node, a destination for which a primary path is defined between the node and the destination, transmitting a request message to a neighbor node for routing information for a backup path between the node and the destination, receiving a reply message containing an address identifying the backup path, and building a backup tunnel to the address. The request message includes at least one node identified as a node to be avoided in the backup path and a request cost. An apparatus for building backup tunnels is also disclosed.