Glossary

CDN (China Content Delivery Network)

Definition

A CDN only speeds up a China visitor when a cached copy sits on an edge server inside the mainland. For mainland China users, "close" means inside the country. An offshore CDN with no mainland edge still serves China visitors from datacenters abroad. A mainland CDN means edge caching on China networks to cut cross-border latency — the edge has to be inside the country for a CDN to touch the cross-border hop.

What the China CDN is

The technology whose edge must sit inside the country. A CDN that cuts China load times has its edge inside the mainland. An offshore edge — however large — does not touch the cross-border hop. Caching assets on offshore CDN nodes does not fix the cross-border transit delay.
Distinct from carrier transit. A carrier transit path is not a content delivery network. CN2 and CMI are the pipes, not the cache. Transit labels do not substitute for a mainland edge.
Filing-gated per acceleration domain. Mainland or global acceleration requires a valid ICP filing first. Outside-mainland-only acceleration — serving only Hong Kong, Macau, or Taiwan — requires a PSB filing instead. Unfiled domains get blocked: if a domain resolves to mainland servers without a filing held at that provider, the provider's monitoring system identifies and blocks access.
A licensed-operator market. The mainland edge is operated only by holders of MIIT-issued CDN licenses. The CDN license is the operator's permit to run the edge; the ICP filing is the site's permit to be hosted. They are different instruments held by different parties.

What the China CDN is not

Not an offshore service that "covers China." A global CDN with no mainland edge does not touch the cross-border hop. Caching assets on offshore nodes leaves the fundamental transit delay unchanged.
Not a fix for filtered endpoints. The Great Firewall (GFW) — the colloquial term for China's filtering of many global internet services — blocks specific services entirely: requests to filtered services are not answered.
Not freely operable by any vendor. The mainland edge is a licensed-operator market. Only MIIT-licensed operators can serve the mainland. No global CDN can serve the mainland without a licensed local partner.
Not the same as carrier transit. CN2 and CMI are carrier transit paths — the pipes that carry traffic. A CDN is the cache layer that sits at the edge. Transit labels do not substitute for a mainland edge.

Why the China CDN matters for foreign companies

Offshore CDNs, compression, and VPNs do not fix the cross-border hop. The durable fix is mainland hosting plus a China-terminating CDN. Not sure which side of the border your current edge sits on? Run the four mainland measurements. The CDN is the hinge between the performance diagnosis and the compliance paperwork. The provider choice within that fix: Alibaba Cloud or Tencent Cloud: the provider decision.

The filing, not the configuration, sets go-live. CDN configuration does not make a domain live for mainland serving — the ICP filing does. Unfiled domains get blocked at the provider level; plan the filing before CDN enablement. The full access-requirements chain is the China CDN article's job, not this page's.

Common misconceptions

"Our global CDN already covers China." Caching offshore does not touch the cross-border hop. A mainland edge is required to cut the transit delay.

"CDN configuration sets go-live." The filing, not the configuration, sets a domain live for mainland serving. Unfiled domains get blocked at the provider level.

"Transit labels like CN2 or CMI substitute for a mainland edge." They are the pipes, not the cache. A carrier transit path is not a content delivery network.

Frequently asked questions

What does a China CDN actually do?

A CDN only speeds up a China visitor when a cached copy sits on an edge server inside the mainland. A mainland CDN means edge caching on China networks to cut cross-border latency — the edge has to be inside the country for a CDN to touch the cross-border hop. An offshore edge — however large — does not touch that hop.

Why doesn’t an offshore CDN fix China load times?

An offshore CDN with no mainland edge serves China visitors from datacenters abroad — caching assets on offshore nodes does not fix the cross-border transit delay. Offshore CDNs, compression, and VPNs do not fix the cross-border hop. The durable fix is mainland hosting plus a China-terminating CDN.

What is the difference between a CDN and carrier transit like CN2 or CMI?

CN2 and CMI are carrier transit paths — the pipes that carry traffic. A CDN is the cache layer that sits at the edge. A carrier transit path is not a content delivery network. Transit labels do not substitute for a mainland edge.

What filing does a China CDN acceleration domain require?

Mainland or global acceleration requires a valid ICP filing first. Outside-mainland-only acceleration — serving only Hong Kong, Macau, or Taiwan — requires a PSB filing instead. Unfiled domains get blocked: if a domain resolves to mainland servers without a filing held at that provider, the provider’s monitoring system identifies and blocks access.

What are the common misconceptions about China CDNs?

Three misconceptions recur. Caching offshore does not touch the cross-border hop — a mainland edge is required to cut the transit delay. The filing, not CDN configuration, sets a domain live for mainland serving. Transit labels like CN2 or CMI are the pipes, not the cache.

Related terms

CDN License (增值电信业务经营许可证—CDN) — the MIIT-issued permit that authorizes an operator to run CDN services in mainland China.
Great Firewall (GFW) — the colloquial term for China’s filtering of many global internet services.
CN2 / CMI Transit — names for carrier networks and transit paths within China’s telecommunications infrastructure.
Bei’an (备案) — ICP Filing — the mandatory registration for most websites hosted on mainland servers.