Network Switch Port Bandwidth Oversubscription Management
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Solution Overview
Problem
Network switches face challenges in managing bandwidth oversubscription, where the aggregate bandwidth of front panel ports exceeds the total bandwidth available on the backplane, leading to changes in traffic profiles and potential priority loss during data switching.
Innovation Solution
Configuring dedicated and shared ports in linecards, with dedicated ports receiving guaranteed bandwidth and low latency, and shared ports utilizing remaining bandwidth, while implementing rate limiting and priority scheduling to ensure that dedicated traffic maintains low latency and priority, even under oversubscription conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the aggregate bandwidth of front panel ports exceeds the backplane bandwidth, then more ports can be supported, but traffic profile changes and priority loss occur
Solution Approach 1:
The patent segments ports into dedicated ports (for critical traffic) and shared ports (for non-critical traffic). This segmentation allows the system to support more total ports while ensuring that dedicated ports maintain their traffic priority and profile even when the aggregate bandwidth exceeds backplane capacity.
2Loss of time
If dedicated ports receive guaranteed bandwidth, then low latency is achieved for critical traffic, but overall bandwidth utilization decreases
Solution Approach 1:
The patent implements dynamic bandwidth allocation where dedicated ports receive guaranteed bandwidth for low latency performance, while shared ports can utilize remaining bandwidth dynamically. This allows the system to maintain low latency for critical traffic while maximizing overall bandwidth utilization through the shared pool.
3Reliability
If rate limiting is applied to manage oversubscription, then bandwidth control is improved, but traffic flow flexibility decreases
Solution Approach 1:
The patent applies rate limiting selectively only to shared ports rather than uniformly across all ports. This local application of bandwidth control maintains traffic flow flexibility for dedicated ports while providing necessary bandwidth management for shared ports, thus preserving overall traffic flow adaptability.
Data Source
AI summary
A number of ports are configured in a linecard in a network device as dedicated ports and a remaining number of ports as shared ports. A total bandwidth allocated to the dedicated ports is computed. It is determined that available bandwidth at a central crossbar is greater than the total bandwidth allocated to the dedicated ports. The total data sent the central crossbar is rate limited to less than the available bandwidth at the central crossbar. First data associated with the dedicated ports is scheduled to the central crossbar using a first priority. Second data associated with the shared ports is scheduled using a second priority. A shared port data is scheduled based on a ration of a bandwidth requirement for the shared port as a fraction of overall bandwidth requirement for the shared ports.