How Alibaba Cloud’s VPC, SLB, and NAT Powered the 2017 Double‑11 Shopping Frenzy

Introduction

In 2017 the Double‑11 shopping festival set new records with a total transaction volume of 168.2 billion yuan, a peak of 325 k transactions per second and 256 k payments per second. Alibaba Cloud’s network products were crucial to handling this massive traffic.

VPC – A Secure Network Container

Virtual Private Cloud (VPC) provides an isolated, secure network environment for each tenant, similar to a private network container on the cloud. Users can place resources such as SLB, RDS, and ECS inside the VPC, choose IP ranges, create subnets, configure gateways, and connect to on‑premise data centers.

During Double‑11 the public cloud platform used VPCs to isolate tenants, preventing communication between different VPCs.

Load Balancer SLB – Traffic Surge Scheduler

Server Load Balancer (SLB) distributes traffic among multiple ECS instances, acting as the entry point for critical business systems. In the Double‑11 peak, SLB received user requests and intelligently routed them to backend ECS servers, ensuring a smooth user experience.

Key performance metrics include peak traffic per second, new connections per second (CPS), maximum concurrent connections (MaxConn), queries per second (QPS), and the number of backend ECS instances.

Example instance data: peak traffic 10 GB/s, CPS 100 k, MaxConn 3 million, backend ECS over 1 000.

NAT Gateway – Enabling Successful Payments

NAT Gateway provides SNAT and DNAT functions. In Double‑11 it mainly offered SNAT so that VPC ECS instances could access the Internet, for example to call Alipay’s payment API.

The payment peak reached 256 k transactions per second, requiring the NAT Gateway to support massive bandwidth, high concurrent connections (up to 3 million), and strong disaster recovery.

High‑Speed Channel – Global Hybrid Cloud Network

Hybrid cloud connects public cloud and on‑premise data centers via dedicated lines, forming a unified network. This architecture protects existing IDC investments while leveraging cloud elasticity, essential for the Double‑11 promotion.

The high‑speed channel provides two main functions: dedicated lines linking IDC to VPC, and VPC inter‑connection across regions.

Infrastructure – Ubiquitous Network Technology

Beyond the network products themselves, the underlying network supports all other systems, such as databases that processed 42 million queries per second during Double‑11, video live streaming, and virtual switches for ECS networking.

In summary, the network was the invisible foundation that delivered a seamless shopping experience during the world’s largest online shopping event.