Dual-Stage Network Scheduler for QoS and Traffic Shaping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional routers fail to scale with increasing line rates and traffic volume, particularly due to the lack of quality of service (QoS) scheduling features such as weighted round robin and per-packet strict priority, which are essential for Internet Service Providers.
Innovation Solution
A network device is designed with a first stage scheduler for QoS scheduling and a second stage scheduler for media-specific scheduling, configured to implement hierarchical virtual path-virtual circuit scheduling, minimum assured rates, and per-packet strict priority, with the ability to shape traffic on a per-cell basis to ensure conformance with Cell Delay Variation Tolerance (CDVT).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a general purpose processor is used to execute routing software, then the router can be flexibly configured with various functionalities, but the router suffers performance degradation and fails to handle traffic at line rate when additional functionality is added
Solution Approach 1:
The router is segmented into multiple specialized components: a purpose-built processor optimized for routing operations, separate memory units for different data types, and dedicated network interface cards. This segmentation allows each component to be optimized for its specific function while working together to maintain high throughput and line rate performance even as functionality is added.
2Device complexity
If conventional single-stage schedulers are used, then the device structure is simpler, but QoS scheduling capabilities such as weighted round robin and per-packet strict priority are not provided
Solution Approach 1:
The scheduling system employs a nested two-stage architecture where the first stage scheduler handles QoS scheduling decisions (weighted round robin, strict priority) and the second stage scheduler handles media-specific scheduling. This nested structure allows complex QoS capabilities to be implemented while maintaining a modular design that doesn't excessively increase overall system complexity.
Data Source
AI summary
In a network device, a line card includes a first scheduler configured to perform scheduling for data units of a first type and a second scheduler that is connected in series to the first scheduler and configured to perform scheduling for data units of a second type. The schedulers may be configured in a variety of ways to achieve certain data unit flow characteristics.