Convergence Node Packet Dropping for In-Order Delivery
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Solution Overview
Problem
In networks that guarantee In-Order Delivery (IOD), the addition of a new equal cost path can lead to out-of-order packet delivery during topology changes, resulting in packet drops and increased latency due to unnecessary retransmissions.
Innovation Solution
Identifying convergence node switches and dropping packets only up to the first convergence node instead of across the entire network, using a modified Dijkstra Shortest Path First algorithm to determine the set of convergence nodes and calculate the number of hops, thereby reducing the time period for packet dropping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a new equal cost path is added to the network, then network redundancy and load balancing are improved, but out-of-order packet delivery occurs during topology changes
Solution Approach 1:
The network path is segmented into multiple segments with convergence nodes identified at specific segmentation points. Packet dropping is applied selectively to segments leading to convergence nodes rather than the entire network path, maintaining IOD only where necessary while allowing flexibility elsewhere.
Solution Approach 2:
Different quality requirements are applied to different network segments. Strict in-order delivery is enforced only up to convergence nodes where path changes occur, while other segments can operate with more flexible packet handling, optimizing overall network performance.
2Reliability
If packets are dropped across the entire network during topology changes, then in-order delivery is maintained, but network resource usage and latency increase
Solution Approach 1:
The packet dropping mechanism is extracted from the entire network and concentrated only at specific convergence nodes. This removes unnecessary packet drops from segments where IOD is already maintained, reducing overall network resource consumption while preserving reliability where needed.
Solution Approach 2:
Instead of applying packet dropping excessively across the entire network, the solution applies partial action only to specific segments leading to convergence nodes. This minimizes the scope of packet dropping to the minimum necessary area, reducing waste of network resources.
3Reliability
If packets are dropped across the entire network, then out-of-order delivery is prevented, but latency increases due to unnecessary retransmissions
Solution Approach 1:
The packet dropping operation is extracted from the entire network path and applied only up to convergence nodes. This eliminates unnecessary packet drops in segments where packets would otherwise be delivered in order, reducing retransmissions and associated latency.
Solution Approach 2:
The solution applies partial packet dropping only where necessary (up to convergence nodes) rather than excessively across the entire network. This minimizes the time packets are held or retransmitted, reducing overall latency while maintaining IOD where required.
Data Source
AI summary
In one embodiment, the convergence node switches of a destination node switch in a network having multiple equal paths between a source switch and destination switch are identified. When a new equal cost path is added to the network, packets are flushed up to the convergence node switch closest to the source switch.