Network Node Path Selection Using Link Delay and Residence Time
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Solution Overview
Problem
Current IP and MPLS networks face challenges in ensuring low-delay traffic requirements due to queuing and congestion, leading to potential packet loss and inability to maintain end-to-end delay within specific thresholds, especially in metropolitan area networks.
Innovation Solution
A method and network node that obtain topology information including physical link delays and node residence times to determine a target transmission path that meets delay requirements, ensuring low-delay service packets are transmitted through paths with minimal delay, thereby improving transmission reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If packet multiplexing network uses DiffServ QoS technology to transmit traffic with different requirements, then traffic can be classified and prioritized, but queuing and congestion still occur causing delay to exceed threshold and packet loss
Solution Approach 1:
The patent segments the transmission path into multiple physical links with measurable delays, allowing independent optimization of each link's contribution to overall delay. By breaking down the end-to-end path into measurable segments (physical link delay + node residence time), the system can identify and optimize specific bottleneck points rather than treating the entire path as a black box.
Solution Approach 2:
The patent implements feedback by measuring actual transmission delays on physical links and using this information to adjust routing decisions. The system measures delay on physical links between nodes and feeds this information back to the routing protocol, enabling dynamic path selection that actively compensates for queuing delays and congestion conditions.
2Adaptability or versatility
If existing routing protocols (IS-IS, OSPF) use link delay as routing measure, then physical link transmission delay can be considered, but no specific link delay measurement mechanism is provided making them unsuitable for metropolitan area networks
Solution Approach 1:
The patent enables routing protocols to self-measure link delays by having network nodes autonomously monitor and report actual transmission delays on their physical links. The measurement mechanism is integrated into the routing protocol itself, allowing nodes to self-optimize routing decisions based on real-time delay conditions without external intervention.
Solution Approach 2:
The patent performs preliminary delay measurement on physical links before making routing decisions. By measuring and pre-calculating the transmission delay (physical link delay plus node residence time) for multiple potential paths, the routing protocol can proactively select the optimal path rather than reacting to delay conditions after they occur.
3Device complexity
If service-layer OAM packet uses same priority queue as service packet after QoS processing, then QoS processing is simplified, but instantaneous queue length affects delay measurement and measurement precision is compromised
Solution Approach 1:
The patent extracts the delay measurement function from the service packet flow by using separate link-layer OAM packets that traverse the physical links independently. This separation allows delay measurement to occur at the link layer before QoS processing, eliminating the confounding effect of queueing on measurement accuracy while maintaining simple QoS processing at the service layer.
Solution Approach 2:
The patent introduces link-layer OAM packets as intermediaries between the service packets and the delay measurement process. These intermediary packets traverse the physical links and enable delay measurement without being affected by service packet queueing behavior, providing accurate link-layer delay information for routing decisions.
4Measurement precision
If channel associated with service traffic is used to measure actual delay of service, then service delay can be measured, but path obtaining is congenitally deficient and cannot measure network-wide delay paths in distributed manner
Solution Approach 1:
The patent transitions from measuring delay in the service layer (one dimension) to measuring delay at the link layer across multiple physical links (multiple dimensions). By measuring delay on each physical link between nodes and aggregating this information, the system gains distributed visibility into network-wide delay paths, enabling comprehensive path optimization.
Data Source
AI summary
A method and network node for obtaining a target transmission path, where the method includes obtaining, by a first network node in a network domain, topology information of a plurality of network nodes on each path between an ingress node and an egress node that are in the network domain, obtaining, by the first network node, a transmission delay of each path according to the topology information, where the transmission delay of each path includes a sum of physical link delays between all network nodes on each path and node residence times of all the network nodes on each path, and determining, by the first network node, the target transmission path according to the transmission delay of each path.