Coordinated Tunnel Rerouting via Intermediate Node Path Computation
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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, preemption cascading, and bandwidth fragmentation, especially during link or node failures, as it lacks coordination among head-end nodes for timing, placement, and bandwidth reservation.
Innovation Solution
An intermediate node computes paths for tunnels that do not include a particular link and informs head-end nodes, allowing them to reroute tunnels over these paths or provides a timestamp for rerouting, thereby coordinating the rerouting process to avoid inefficiencies and ensure all tunnels can find acceptable paths.
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 failures and preemption cascading occur due to lack of coordination among head-end nodes
Solution Approach 1:
An intermediary coordinator entity is introduced to mediate between head-end nodes during tunnel rerouting. The coordinator receives rerouting requests from head-end nodes, computes coordinated paths that avoid preemption cascading, and returns approved paths to the head-end nodes. This intermediary structure maintains the distributed architecture's flexibility while preventing signaling failures through centralized coordination.
2Adaptability or versatility
If distributed path computation is used for tunnel rerouting, then scalability is improved, but bandwidth fragmentation occurs due to lack of coordination in tunnel placement
Solution Approach 1:
The coordinator implements a feedback mechanism where head-end nodes report tunnel placement decisions and bandwidth usage to the coordinator. The coordinator uses this feedback information to make informed routing decisions for subsequent rerouting requests, optimizing bandwidth utilization across the network and preventing fragmentation while maintaining scalability.
3Productivity
If coordinated path computation is implemented at an intermediate node, then tunnel placement optimization is improved, but device complexity increases due to additional coordination mechanisms
Solution Approach 1:
The coordination function is segmented from head-end nodes and placed at a dedicated intermediate coordinator node. This segmentation allows head-end nodes to remain simple while the coordinator handles the complex path computation and coordination logic. The segmented architecture improves tunnel placement efficiency without significantly increasing complexity at individual network nodes.
Data Source
AI summary
In one embodiment, a set of tunnels is determined that traverse a particular link connected to an intermediate node in a network. The intermediate node computes, in a coordinated path computation, paths for tunnels of the set of tunnels that do not include the particular link. The coordinated path computation considers each of the tunnels of the set of tunnels. The intermediate node selects one or more tunnels of the set of tunnels for preemption. The one or more tunnels are selected as tunnels that are reroutable by respective head-end nodes of the one or more other tunnels. Notifications are sent to one or more other intermediate nodes that inform the one or more other intermediate nodes of the one or more tunnels selected for preemption.