QoS Filter for Upstream Over-Subscription Management
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Solution Overview
Problem
Conventional network architectures face challenges in managing bandwidth demands, leading to oversubscription issues at upstream interfaces, where low priority traffic is not effectively discarded, resulting in unacceptable latency and performance degradation.
Innovation Solution
A packet-processing unit in a switch device is reconfigured to identify Quality of Service (QoS) information for incoming packets using maps and perform line-speed lookups, allowing for the selective forwarding of high-priority traffic while discarding low-priority packets to ensure timely processing of control plane packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upstream interface processes all incoming packets without discrimination, then no packets are lost, but the interface becomes oversubscribed and latency becomes unacceptable
Solution Approach 1:
The patent applies local quality by assigning different service levels to different packets based on their priority classification. High-priority packets receive guaranteed bandwidth and preferential treatment in the upstream interface, while low-priority packets are subject to discarding when bandwidth is insufficient. This differential treatment resolves the contradiction by ensuring critical packets are delivered reliably without being delayed by non-critical traffic.
Solution Approach 2:
The patent changes the parameter of packet handling from uniform processing to priority-based processing. By introducing QoS parameters and classification mechanisms, the system transforms how packets are treated in the upstream interface, allowing selective prioritization that maintains reliability for important packets while managing overall latency through controlled discarding of lower-priority traffic.
2Loss of time
If the upstream interface guarantees bandwidth for high-priority traffic, then latency for critical packets is reduced, but low-priority traffic may be excessively discarded
Solution Approach 1:
The patent implements partial action by providing guaranteed bandwidth only to high-priority traffic rather than attempting to serve all traffic equally. The upstream interface applies excessive action to high-priority packets by reserving sufficient bandwidth to ensure their timely delivery, accepting that this may result in some low-priority packet discarding. This resolves the contradiction by focusing resources where they are most needed.
Solution Approach 2:
The patent applies local quality by creating different service zones within the upstream interface - a guaranteed bandwidth zone for high-priority traffic and a best-effort zone for low-priority traffic. This localized differentiation allows the system to optimize latency for critical packets without completely starving lower-priority traffic, resolving the contradiction between latency reduction and packet volume delivery.
3Device complexity
If conventional packet processing is used without QoS classification, then device complexity is low, but performance under oversubscription conditions deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the packet processing function into distinct stages: classification stage (identifying packet priority), marking stage (applying QoS labels), and upstream forwarding stage (priority-based scheduling). This segmentation allows the device to maintain relatively simple individual components while achieving high overall performance through coordinated operation, resolving the contradiction between simplicity and productivity.
Solution Approach 2:
The patent implements preliminary action by performing packet classification and QoS marking before packets reach the upstream interface. This advance preparation allows the upstream interface to operate with simple priority-based rules rather than complex real-time decision-making, maintaining device simplicity while achieving high performance through pre-computed priority assignments.
Data Source
AI summary
A switch device can be configured to operate in a manner that was not originally intended. For example, a switch device can be a Broadcom XGS type of device that is configured with a packet-processing unit to perform line speed lookups in accordance with a default configuration. The default configuration can include classifying and forwarding received packets to an upstream interface based on VLAN information. The default configuration can be overwritten such that the switch device operates in a different manner than originally intended. For example, the switch device can be reconfigured to include mapping rules that specify different QoS data to be assigned to different type of received packets. Subsequent to utilizing the maps to identify QoS information for received packets, the reconfigured switch device uses the QoS information to forward the packets to queues in an upstream interface.