Flow Redirection Using State Information for Hash Rebalancing
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Solution Overview
Problem
Transparent network traffic redirection protocols like WCCP face challenges in troubleshooting and resource utilization due to the rebalancing of hash buckets when new Traffic Processing Entities (TPEs) are added, leading to unclear traffic processing paths and increased failure surfaces, as well as bandwidth and processing capacity wastage.
Innovation Solution
A system with a redirection module and flow monitoring and state information module that determines whether state information exists for a packet before routing it, allowing for the redirection of packets to the correct processing device, even during the insertion or failure of TPEs, by maintaining state information for active flows and updating it when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hash buckets are rebalanced when new TPEs are inserted, then load distribution across TPEs is improved, but flow consistency is degraded causing packets to be sent to wrong TPEs
Solution Approach 1:
The patent segments the flow state management by introducing per-flow state tables that track which TPE is handling each flow. This segmentation allows the system to maintain flow-specific routing information independently from the overall hash bucket assignment, enabling hash rebalancing without disrupting existing flows.
Solution Approach 2:
The patent introduces flow state information as an intermediary layer between the hash bucket assignment and actual packet routing. This intermediary stores the mapping between flows and their assigned TPEs, allowing the system to override default hash-based routing decisions and ensure packets are sent to the correct TPE even when hash buckets are rebalanced.
2Reliability
If flow protection is implemented, then packet delivery reliability is improved, but troubleshooting complexity increases due to unclear traffic paths
Solution Approach 1:
The patent makes the invisible flow state visible by maintaining and potentially logging flow-to-TPE mapping information. This visibility allows operators to trace which TPE is handling which flow, making troubleshooting straightforward while maintaining the reliability benefits of flow protection.
3Productivity
If packets are rerouted to TPEs with no flow knowledge, then load balancing is improved, but bandwidth and processing capacity are wasted
Solution Approach 1:
The patent performs preliminary action by pre-establishing flow state information that identifies the correct TPE for each flow before packet routing decisions are made. This preliminary knowledge prevents unnecessary rerouting and the associated waste of bandwidth and processing capacity while still allowing load balancing for new flows.
Data Source
AI summary
In an example embodiment, there is disclosed an apparatus comprising a first interface configured to receive a packet from a client, a second interface configured to transmit the packet to a server, a third interface configured to communicate with at least one processing device, redirection module in communication with the first interface, the second interface and the third interface, and flow monitoring and state information module in communication with the first interface, the second interface, the third interface and the redirection module. Responsive to receipt of the packet on the first interface, the redirection module is operable to communicate with the flow monitoring and state information module whether state information exists for the packet, the state information comprising an address for a processing device. The redirection module is operable to route the packet to the processing device responsive to determining state information exists for the packet.