Path Continuity Determination in Aggregate Flow Networks
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Solution Overview
Problem
In centralized control plane networking architectures, determining path continuity between datapath nodes in an aggregate flow environment is challenging due to reduced flow granularity, which can make it difficult to measure path characteristics like packet loss and delay, especially when multiple independent flows are aggregated.
Innovation Solution
The mechanism involves devolving aggregate flows into microflows with timers at ingress and downstream nodes, which are then terminated and reported to the controller node to determine path continuity, utilizing existing network traffic instead of probe packets, thus eliminating the need for specialized nodes and reducing network bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aggregate flow entries are used to forward packets, then controller node processing requirements and communications are reduced, but flow granularity is lost making path continuity determination difficult
Solution Approach 1:
The patent segments aggregate flows into microflows by introducing flow identifiers that distinguish individual flows within an aggregate flow. This segmentation allows the controller to track specific flow paths while the datapath nodes continue to use aggregate flow entries for efficient packet forwarding. The microflow concept divides the coarse-grained aggregate flow into finer-grained individual flow instances, enabling path continuity determination without requiring separate aggregate flow entries for each flow.
2Measurement precision
If active measurement mechanisms with probe packets are used, then path continuity can be determined, but network traffic increases and specialized functionality is required
Solution Approach 1:
The patent enables the network flows themselves to serve the measurement function by utilizing existing data packets rather than requiring separate probe packets. The flow identifiers embedded in normal traffic packets allow the controller to track path continuity using the actual traffic that needs to be measured, eliminating the need for additional measurement traffic. This self-service approach uses the production traffic (data packets) to perform the measurement function.
3Measurement precision
If continuous examination of flow tables is performed, then path continuity can be monitored, but controller node overhead increases substantially
Solution Approach 1:
The patent performs preliminary action by having datapath nodes pre-process flow information and generate microflow identifiers before packets reach the controller. The nodes prepare flow tracking data in advance using the flow identifier mechanism, so that when the controller needs path continuity information, it is already available in a processed format. This eliminates the need for continuous real-time examination of flow tables by the controller.
Data Source
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AI summary
Mechanisms for path continuity determination in an aggregate flow environment. An ingress node and a downstream node for which a path continuity check is desired are determined. The ingress node devolves, from an aggregate flow entry, one or more microflows that comprise packets which are destined for the downstream node. The downstream node is directed to generate corresponding microflows. Each microflow is associated with a continuity set identifier and has one or more timers, such as an idle timer and/or a hard timeout timer. Upon timeout of one of the timers, the ingress node and the downstream node send a microflow termination message that contains the continuity set identifier to a controller node. The controller node determines a path continuity status between the ingress node and the downstream node based on a receipt of one or more microflow termination messages from the ingress node and the downstream node.