IPv6 Migration Architecture and Implementation for Xianyu Mobile App

IPv6, the next‑generation IP protocol, was standardized in 1995 (RFC1883) to solve IPv4 address exhaustion and improve forwarding efficiency and security. After years of slow adoption, large‑scale deployment began only recently, especially in China where, since May 2018, the three major carriers upgraded their mobile networks to IPv6.

Xianyu, Alibaba’s largest second‑hand trading community, initiated an IPv6 migration to comply with national policy and prepare for future technology shifts.

IPv6 Application Architecture

The app’s network flow is:

DNS resolves domain names.

Static resources (images, JS) are fetched from CDN.

Business APIs are called via HTTPS to an LVS load balancer, then to an aserver (similar to Nginx), and finally to backend services through the mtop RPC layer.

IPv6 Solution

Based on Alibaba’s group‑wide IPv6 architecture, the migration uses NAT at the LVS layer to translate IPv6 to IPv4, while embedding the client’s IPv6 address in an HTTP header for downstream services. This minimizes backend changes; future full‑stack dual‑stack support is planned.

Renovation Principles

Testable, gray‑releaseable, monitorable, and rollback‑able.

Support IPv4/IPv6 dual‑stack to avoid user impact.

Gradual rollout: small modules → full business, branch services → core services.

Android first, then iOS.

Prioritize mobile traffic; PC traffic is low.

Migration Steps

Identify modification points in app and backend.

Upgrade app SDK and backend to IPv6‑compatible versions.

Internal gray testing of IPv6‑enabled app.

Public gray release and gradual traffic scaling via amdc for service and CDN domains.

Specific Changes

Upgrade network SDK to IPv6‑compatible version.

Front‑end IP handling logic to accept IPv6 format.

Backend services and databases to store IPv6 addresses.

LBS services to use IPv6 address libraries.

User profiling, search, and recommendation modules to support IPv6.

Testing Methods

Ensure local device is on a dual‑stack network (e.g., Wi‑Fi).

Use dedicated IPv6 testing tools (e.g., www.dotouch.net.cn).

Web‑based IPv6 access tests.

Log inspection for IP information.

Release Strategy & Monitoring

Gray release includes separate app rollout, front‑end/backend deployment, and domain scaling. Monitoring covers IPv6 CDN quality, traffic share, request latency, error rates, and IPv6 DAU/MAU metrics.

Since the IPv6 rollout at the end of last year, Xianyu’s IPv6 daily active users have reached ~55%, with stable operation and plans to expand IPv6 capability across more domains.