If your users are in mainland China, the network route between your server and China matters more than almost anything else. International links into China are notoriously congested at peak times, and a normal server in the US or even Hong Kong can show high latency and heavy packet loss in the evening. CN2 and especially CN2 GIA are China Telecom’s premium networks that avoid much of this congestion. Here’s what the terms mean.
China Telecom’s networks in brief
China Telecom operates two main backbones:
| Network | AS | Description |
|---|---|---|
| ChinaNet (163 backbone) | AS4134 | The main, large-capacity network. International links are heavily shared and often congested at peak hours |
| CN2 (ChinaNet Next Carrying Network) | AS4809 | A newer, premium backbone with more capacity per user, better QoS and lower loss |
CN2 comes in two flavours for international traffic:
- CN2 GT (Global Transit): traffic uses CN2 internationally, but within China it may still run partly over the 163 backbone. It’s better than plain 163, but can still congest at peak times.
- CN2 GIA (Global Internet Access): traffic stays on CN2 end to end, inside China and internationally. It’s the most consistent latency and lowest packet loss of China Telecom’s international products, and the most expensive.
The other big Chinese carriers have premium international products too: China Unicom (AS9929/AS10099, “CU premium”) and China Mobile (CMIN2/CMI).
Why it matters
From mainland China to a typical server abroad:
| Route | Typical behaviour (to the US West Coast) |
|---|---|
| Standard 163 | 150–200 ms off-peak, often 250 ms+ with 5–20% loss at evening peak |
| CN2 GT | Better, but can degrade at peak |
| CN2 GIA | ~130–170 ms, low loss, stable across the day |
For Hong Kong and Japan, the distances are shorter, so latency is much lower (often 30–60 ms to Hong Kong from South China), but route quality still decides stability.
Packet loss hurts more than latency. A few percent loss cripples TCP throughput, and makes sites feel broken. See packet loss troubleshooting and latency vs bandwidth.
Return path vs outbound path
Routes are often asymmetric:
- Outbound (server → China) is what matters most for websites and downloads, since that’s where the data flows.
- Inbound (China → server) carries requests and uploads.
Providers sometimes describe “CN2 GIA return” or “three-network optimised” routes. Ask which direction is optimised, and for which carriers (Telecom, Unicom, Mobile).
Check the route yourself
From a machine in mainland China (or using route-testing services and probes there), trace the path to the server:
mtr -rwzc 100 203.0.113.10Look at the hops inside China:
- addresses in 59.43.x.x are characteristic of CN2 routers;
- 202.97.x.x belongs to the 163 backbone;
- the AS numbers in mtr’s output (
-z): AS4809 = CN2, AS4134 = 163.
From the server to China (the return path), trace to a China Telecom IP from the server itself. Test at evening peak hours in China (roughly 20:00–23:00 Beijing time), when the differences are largest. See ping, traceroute and mtr.
Choosing a server location for Chinese users
| Location | Latency to South China | Notes |
|---|---|---|
| Hong Kong | Lowest (~20–50 ms) | Closest. Route quality varies by provider |
| Japan (Tokyo) | Low (~50–90 ms) | Good alternative, good connectivity to Asia |
| USA West Coast | Higher (~130–170 ms on good routes) | Fine with CN2 GIA. Typically larger bandwidth for the price |
Also consider ICP filing requirements if you’d like to host inside mainland China. Servers abroad avoid that, but depend on cross-border routes.
VPS.DO’s options for China-focused traffic: Hong Kong VPS on CN2 + BGP, and Japan VPS (Tokyo) with international and CN2 GIA routing. You can test both from your location before ordering with the published test IPs. See Hong Kong VPS, Japan VPS and China network latency.
Other ways to improve China access
- Serve static assets via a CDN with good China coverage (international CDNs vary a lot there).
- Reduce round trips: HTTP/2 or HTTP/3, TLS 1.3, fewer third-party requests (some, such as Google Fonts and reCAPTCHA, are blocked in China). See HTTP/1.1 vs 2 vs 3 and local fonts.
- Enable TCP BBR, which handles lossy paths better. See TCP BBR.
Quick reference
| Term | Meaning |
|---|---|
| 163 / ChinaNet (AS4134) | China Telecom’s main backbone, often congested internationally |
| CN2 (AS4809) | Premium backbone |
| CN2 GT | CN2 internationally, mixed inside China |
| CN2 GIA | CN2 end to end, the most stable |
| 59.43.x.x hops | CN2 routers |
| 202.97.x.x hops | 163 backbone |
Related: choosing a VPS location and BGP basics.