An Operator’s Perspective On Why Alibaba Cloud Japan Doesn’t Use CN2 And An Assessment Of Its Impact On Access Speed

1.

Operator’s Perspective: The reason why Alibaba Cloud Japan doesn’t use CN2

Whether Alibaba Cloud’s Japanese nodes use CN2 is first affected by BGP policies and cooperative peering relationships.
Operators will decide whether to open CN2 access based on cost, routing stability, and traffic engineering.
CN2 is China Telecom’s dedicated network for high-quality transmission, but not all cloud provider nodes are directly connected or have this feature enabled.
Alibaba Cloud in Japan may rely more on multi-operator interconnection, direct overseas backbones, or third-party transmission to prioritize stability and resilience.
From the operator’s perspective, whether to use CN2 also depends on the type of traffic (gaming/streaming/enterprise applications) and the contract.

2.

Routing and Latency: Key points for technical evaluation

To determine whether to use CN2, one needs to consider the BGP routing path and the length of the AS path; operators can use routing monitoring platforms to check this.
CN2 usually provides fewer hop counts and better congestion control, thereby reducing latency and jitter.
But if Alibaba Cloud chooses a multi-path solution that connects directly to Japan, in some cases, delays from paths other than CN2 can also compete.
International export bandwidth utilization, undersea cable congestion, and the impact of local exchange points (IX) on performance also need to be considered.
Considering both latency and packet loss, operators prioritize stability and throughput over the lowest single-point RTT.

3.

Actual measurement data demonstration: CN2 and Alibaba Cloud Japan (example measurement)

The following are example measurements (samples) from the operator’s laboratory comparing two routes from Beijing, China, to Japan.
The table shows the average RTT, packet loss rate, and stable bandwidth, with data representing example results from a 5-minute stability test.

Path Type	Average RTT (ms)	Packet Loss Rate (%)	Stable Bandwidth (Mbps)
China Telecom CN2 (example)	62	0.2	95
Alibaba Cloud Japan Default Cross-Border	85	0.8	82

The above data are example measurements; actual conditions vary due to fluctuations in rooms, time periods, and submarine cable status.

4.

Real cases: Comparison of Experience After Migrating Games to CN2

A domestic game company migrated its Tokyo data center from a third-party provider to Alibaba Cloud Japan, and the operator conducted an A/B comparison.
Before migration, direct connection via CN2 was used, with the peak RTT remaining stable at 60–70 ms during peak usage times, and frame loss below 0.5%.
After migrating to Alibaba Cloud Japan, the RTT increased to 80–120 ms at certain times. Network jitter and short-term packet loss increased, affecting the player experience.
The operator ultimately recommended a hybrid approach: Critical paths use CN2 as a backup, while non-critical traffic uses Alibaba Cloud’s default exit to control costs.
This case shows that different BGP policies have a direct impact on the business experience, and trade-offs need to be made based on the type of service.

5.

Examples of server and network configurations: How to optimize cross-border access

Example of instance configuration: ECS type: ecs.c6.large (2 vCPUs/4GB), public network bandwidth: 100 Mbps, region: ap-northeast-1 (Tokyo, Japan).
Kernel and network optimization suggestions (example sysctl): net.ipv4.tcp_congestion_control=bbr ； tcp_tw_reuse=1 ； net.core.rmem_max=16777216.
BGP/Multi-line Recommendations: Procurement support for direct CN2 connection or establishment of dedicated lines with domestic operators, using Anycast or layer-4 load balancing to manage traffic routing.
CDN and Acceleration: By placing static resources on domestic nodes and enabling cross-border origin-pull optimization, reducing the number of cross-border requests can significantly lower perceived latency.
DDoS protection: Enable Anti-DDoS/cleaning at the edge (provided by Alibaba Cloud or operator cleaning centers) to prevent the link from being exhausted at critical moments.

6.

Summary of Operator Recommendations and Implementation Strategies

Determining whether CN2 is necessary should be decided based on three aspects: business SLAs, cost, and operability.
For latency-sensitive applications (games, voice), prioritize CN2 or dedicated lines to reduce latency and jitter.
For static content or bandwidth-intensive services, proper use of CDN, compression, and concurrency control can compensate for some of the advantages of CN2.
Monitoring should be in place during deployment: RTT, packet loss, bandwidth usage, and BGP path change logs to quickly trigger rollback or traffic switching.
Finally, it is recommended to communicate with service providers and cloud vendors to clarify Peering and SLAs, and implement a comprehensive solution that combines multiple connections, CDN, and DDoS protection.