Distributed Tunnel Rerouting with Intermediate Node Feedback
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Solution Overview
Problem
Distributed path computation in computer networks is inefficient for optimizing tunnel placement and rerouting, leading to signaling failures, bandwidth fragmentation, and inability to maintain bandwidth guarantees during link or node failures, due to the lack of coordination among head-end nodes.
Innovation Solution
A head-end node determines the need to reroute tunnels, computes paths with available bandwidth, establishes tunnels with zero bandwidth, and receives feedback from intermediate nodes to resize tunnels based on a bandwidth scaling factor, ensuring fair bandwidth allocation and rerouting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If distributed path computation is used for tunnel rerouting, then flexibility and scalability are improved, but signaling coordination and bandwidth allocation efficiency deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where intermediate nodes send bandwidth availability information back to head-end nodes. This allows head-end nodes to make informed rerouting decisions based on real-time network state, resolving the contradiction by enabling coordinated bandwidth allocation while maintaining distributed architecture flexibility.
Solution Approach 2:
The patent introduces an intermediary feedback mechanism between head-end nodes and intermediate nodes. The intermediate nodes act as mediators that provide bandwidth status information, enabling indirect coordination without requiring direct peer-to-peer communication between all head-end nodes, thus maintaining scalability while improving coordination.
2Extent of automation
If distributed rerouting is performed independently by each head-end node, then autonomy and scalability are improved, but signaling coordination and bandwidth fragmentation worsen
Solution Approach 1:
The feedback mechanism allows head-end nodes to maintain autonomy in making rerouting decisions while receiving critical bandwidth coordination information from intermediate nodes. This resolves the contradiction by enabling independent automation with access to shared network state information.
Solution Approach 2:
Each head-end node independently processes feedback information and makes its own rerouting decisions without requiring centralized control. This maintains autonomy and scalability while the feedback mechanism ensures bandwidth coordination, allowing nodes to serve themselves with coordinated information.
3Speed
If multiple tunnels are rerouted simultaneously during link failure, then service restoration speed is improved, but signaling failures and preemption cascading increase
Solution Approach 1:
The patent enables head-end nodes to prepare rerouting paths in advance using feedback information about bandwidth availability, before actual failures occur. When link failures happen, pre-computed paths can be activated quickly without causing signaling storms, thus achieving fast restoration while maintaining signaling reliability.
Solution Approach 2:
The feedback mechanism provides advance information about bandwidth constraints, allowing the system to cushion against potential preemption cascades by selecting rerouting paths that respect bandwidth limits. This prevents the chain reaction of preemptions while maintaining fast restoration capability.
4Reliability
If bandwidth is reserved for guaranteed traffic, then quality of service is improved, but bandwidth availability for other tunnels deteriorates
Solution Approach 1:
The patent implements dynamic bandwidth allocation where the feedback mechanism continuously monitors bandwidth usage and adjusts available bandwidth information in real-time. This allows the system to maintain bandwidth guarantees for priority traffic while dynamically adapting to available capacity for other tunnels, resolving the contradiction between reliability and adaptability.
Data Source
AI summary
In one embodiment, a head-end node determines a path for un-reroutable tunnels, and establishes a tunnel having zero bandwidth indicating the corresponding bandwidth desired for the tunnel. Intermediate nodes send feedback regarding a bandwidth scaling factor for the path, and the head-end node resizes each tunnel accordingly.