East-west traffic dominates modern data centers, and the latency and throughput of mutual access between servers are directly determined by the network topology. The three-tier architecture seems mature and stable, but it is easy to hit bottlenecks after virtualization and distributed storage scale. This article summarizes the differences between the two architectures and the switching judgment method.

What are the inherent bottlenecks of the three-tier architecture?

Traffic in a three-layer structure often passes through three hops: access, aggregation, and core, with delays gradually superimposed. The aggregation layer is a natural convergence point. Once the active and backup links are imbalanced, the overall excess convergence ratio will increase significantly. At the same time, in order to avoid loops, traditional anti-loop protocols will block redundant links and reduce bandwidth utilization. Horizontal expansion often means replacing the entire machine rather than smoothly adding boxes.

The non-blocking advantage of Spine-Leaf

• Each Leaf is interconnected with all Spine, with two fixed hops at any two points, and the latency is low and predictable.
• Combined with equal-cost multipath ECMP, the upstream bandwidth is utilized in parallel, and the convergence ratio can be lowered
• Just add Leaf to new cabinets, and horizontal expansion is smooth, suitable for virtualization, distributed storage and AI clusters

Upgrade timing and link matching

When the scale is small and the north-south direction is dominant, the initial investment of three layers is more economical; when the number of server cabinets increases significantly and the east-west traffic accounts for more than half, upgrade to two layers. When upgrading, Leaf upstream can be used first.100G DAC high speed cableCovers short distances and is configured on the server sidePCI-EX16 100G dual optical port fiber optic network card (Intel Intel E810 chip), and then gradually introduce higher rates.

There is no absolute answer to the topology. The key depends on the traffic model and expansion rhythm. EB-LINK has modules and network cards from 10G to 100G in stock. You can call 0755-83179002 to get a transition plan that matches existing equipment.