Inter-Switch Link Preserves Packet Order During TOR Migration
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Solution Overview
Problem
In cloud computing environments, Load-Based Teaming (LBT) policies cause out-of-order packet delivery during active link migration between Top-of-Rack (TOR) switches, leading to decreased computing performance and network congestion due to the need for reassembly of packets at the destination host.
Innovation Solution
Establishing an inter-switch link between TOR switches to ensure that post-migration packets follow the same network path as pre-migration packets, maintaining correct ordering and reducing the need for reassembly at the destination host.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Load-Based Teaming (LBT) policies are used for load balancing across physical network interface cards, then network load distribution is improved, but packet delivery order deteriorates during active link migration
Solution Approach 1:
The patent introduces a distributed virtual switch as an intermediary component between the physical network interface cards and virtual machine network interface cards. This intermediary tracks active link migrations and intercepts packets to reorder them before delivery, thus resolving the contradiction between load balancing and packet order maintenance. The distributed virtual switch acts as a mediator that manages the complexity of packet routing across multiple fabric networks while preserving delivery semantics.
2Adaptability or versatility
If active link migration between TOR switches is implemented, then network flexibility and load balancing are improved, but computing performance deteriorates due to packet reassembly requirements
Solution Approach 1:
The patent implements preliminary action by pre-tracking active link migrations and pre-intercepting packets before they reach the destination host. The distributed virtual switch proactively monitors link migration events and prepares packet reordering mechanisms in advance, eliminating the need for post-delivery reassembly operations at the destination host. This preliminary intervention maintains network flexibility while preventing computing performance degradation.
3Adaptability or versatility
If packets are transmitted across multiple fabric networks during active link migration, then network path options are improved, but network congestion worsens due to re-transmitted packets
Solution Approach 1:
The patent implements feedback mechanisms where the distributed virtual switch continuously monitors packet delivery status and link migration events. When out-of-order packets are detected or link migrations occur, the system provides feedback to adjust packet routing decisions in real-time. This feedback loop ensures packets are delivered through optimal paths without generating unnecessary re-transmissions, thus maintaining network path options while controlling traffic volume.
Data Source
AI summary
An example to preserve packet order in a multi-fabric network includes: a migration detector to, after a first host sends a first packet of a first packet flow via a first active link between a first host and a first top-of-rack (TOR) switch, detect a migration of the first active link to a second active link between the first host and a second TOR switch, the first packet destined to a second host connected to the second TOR switch; and a migration notifier to, in response to the migration, send a migration notification message to cause configuration of the second TOR switch to send a second packet of the first packet flow to the first TOR switch via an inter-switch link between the first and second TOR switches, the second packet destined to the second host.