Control Message Relay for Switch CAM Capacity Management
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Solution Overview
Problem
In centralized-control-type networks, switches with limited Content Addressable Memory (CAM) capacity face challenges in setting and managing control information, leading to errors and increased burden on control apparatuses, especially when using resource-balancing brokers like FlowVisor.
Innovation Solution
A control message relay apparatus and method that stores and converts control information between a control apparatus and switches, using a control information storage unit and conversion unit to manage setting status and reflect control policies, facilitating the setting of control information without unifying CAM capacities across switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If switches use CAM to hold control information for high-speed packet processing, then packet processing speed is improved, but CAM capacity is limited and expensive
Solution Approach 1:
The patent introduces a control message relay apparatus as an intermediary between the control apparatus and switches. This relay apparatus stores control information and converts control messages, allowing switches to process packets at high speed using their limited CAM while the relay apparatus handles the burden of managing control information across multiple switches with different CAM capacities.
2Reliability
If control apparatus sets control information directly in switches, then control information is accurately set, but burden on control apparatus increases when CAM is full and error handling is required
Solution Approach 1:
The control message relay apparatus serves as a mediator that receives control messages from the control apparatus, determines whether control information can be set in the target switch, and manages error conditions. This intermediary approach maintains reliable control information setting while reducing the burden on the control apparatus by handling CAM capacity checks and error management centrally.
Solution Approach 2:
The relay apparatus implements feedback by determining whether control information setting is possible before attempting to set it, and by managing error conditions that arise when CAM is full. This feedback mechanism prevents control apparatus from attempting to set uncontrollable configurations, reducing unnecessary burden and errors.
3Adaptability or versatility
If FlowVisor is used for resource balancing among multiple control apparatuses and switches, then resource allocation is optimized, but CAM capacity limitation is further exacerbated
Solution Approach 1:
When FlowVisor is present in the system, the control message relay apparatus continues to function as an intermediary between FlowVisor and the switches. This layered intermediary approach allows FlowVisor to perform resource balancing and allocation across multiple control apparatuses while the relay apparatus handles the specific task of managing CAM capacity limitations at the switch level.
Data Source
AI summary
A control message relay apparatus is arranged between a switch that processes a packet(s) based on externally set control information and a control apparatus that sets the control information in the switch. The control message relay apparatus comprises a control information storage unit that stores control information received from the control apparatus and information indicative of a setting status of the control information in the switch; and a control information conversion unit that reflects a control content(s) received from the control apparatus in control information held in the switch based on a predetermined control policy(ies).