Intelligent Buffering for Packet Reordering in Network Devices
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Solution Overview
Problem
In computer networks, packet reordering occurs when internal forwarding paths in network devices change, causing packets to be transmitted on a new path before those on the initial path are fully transmitted, leading to reordering issues at the destination.
Innovation Solution
Implementing intelligent buffering in network devices to delay packet transmission on a new path by a buffering time period equal to the time it takes for packets to travel from the source to the initial destination, ensuring that all packets are reordered behind those already in flight on the initial path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If internal forwarding paths are dynamically changed to improve load balancing and reduce latency, then network efficiency is improved, but packet reordering occurs at the destination
Solution Approach 1:
The patent applies preliminary action by calculating and storing the transmission time of packets on the initial path before the path change occurs. When packets are forwarded on the new path, the system uses these pre-calculated time values to determine appropriate buffering durations, ensuring that packets arrive at the destination in the correct order despite the path change.
Solution Approach 2:
The patent introduces an intermediary buffering mechanism at the egress packet processor. This buffer acts as a mediator between the new fast path and the destination, temporarily holding packets forwarded on the new path until packets from the initial path have been transmitted, thereby preventing reordering without affecting the benefits of the path change.
2Reliability
If packets are buffered on the new path to maintain packet order, then packet reordering is resolved, but transmission delay increases
Solution Approach 1:
The system performs preliminary calculation of transmission times for packets on the initial path before the path change. This allows the egress packet processor to determine the exact buffering duration needed for packets on the new path, buffering them only long enough to maintain order without unnecessary delays.
Solution Approach 2:
The patent dynamically adjusts the buffering time parameter based on the calculated transmission time of packets on the initial path. By changing the buffering duration parameter to match the actual transmission time, the system minimizes delay while ensuring packets are delivered in the correct order.
Data Source
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AI summary
The techniques describe packet reordering for packets flowing on a new path in response to a change in internal forwarding paths in a network device. For example, a network device may dynamically change the selection of an internal forwarding path to achieve fabric path optimization ("OFP") or to ensure optimized load balancing. Packets forwarded on the new path are buffered such that the transmission of packets forwarded on the new path are delayed for a buffering time period of at least the time in which a packet is being sent from the source packet processor to the initial destination packet processor.