Before purchasing a VPS, it's recommended to test the IP address, a point that beginners might overlook. The popularity of IIJ lines in Japan has been steadily rising in recent years, becoming a popular choice after SoftBank due to their balanced performance across three major networks (China Telecom, China Unicom, and China Unicom) and stable backbone network quality. However, the quality of IIJ VPSs on the market varies greatly; even those labeled "IIJ line" can offer vastly different experiences. This article shares a complete testing methodology to help you understand the true performance of an IIJ VPS before placing an order.
What exactly is an IIJ line? Why is it worth testing?
IIJ, short for Internet Initiative Japan, is a long-established ISP and backbone network service provider in Japan. Its IP-Transit service offers thousands of routes and prefixes, peering with multiple mainstream NSPs and CSPs, boasting redundant links and high SLA commitments.
The core characteristic of IIJ lines is "balanced performance across three networks, without specialization." Compared to SoftBank lines, which focus more on optimizing for users returning to China for China Telecom and China Unicom, IIJ lines prioritize backbone network quality and global egress stability. Real-world testing data shows that the average latency of the IIJ line under China Unicom's network is approximately 103ms, with a packet loss rate of 1.2%. Network quality for China Telecom users is roughly the same as for Unicom. Performance for China Mobile users depends on regional network conditions.
Who is the IIJ line suitable for? If your business needs to connect not only to mainland China but also to other parts of Asia or globally, IIJ is a more balanced and reliable choice. It is particularly suitable for scenarios with high stability requirements, such as cross-border SaaS, global API services, cross-regional data synchronization, and global CDN origin nodes. Conversely, if your core users are all located in mainland China and you are extremely sensitive to latency, SoftBank may be a better solution.
Before Testing: Obtain the Correct Test IP
Reputable VPS providers usually publish test IPs and data center information on their official websites, allowing users to test before purchasing.
Taking Jtti as an example, its Japan IIJ line VPS provides explicit test IPs:
- Japan Cloud Server: 103.110.221.254
- Japan Light Cloud Server: 142.248.139.254
Once you have the test IPs, you can begin systematic testing. Note: Before testing, be sure to close private virtual networks, proxies, or traffic shaping software, as these tools may alter routing paths, leading to distorted test results.
First Challenge: Ping Latency Test – Quickly Determine "Speed"
Ping is the most basic and intuitive testing method. Open a command line locally (CMD for Windows, Terminal for Mac/Linux) and execute:
ping testIP -n 50 (Windows)
ping -c 50 testIP (Mac/Linux)-c or -n 50 means sending 50 data packets. Focus on three key metrics: average latency (lower is better), maximum latency (reflecting fluctuations), and packet loss rate (be wary if it exceeds 1%).
The following are reference latency values for the IIJ line:
- Shanghai Telecom → Tokyo IIJ: Approx. 32ms
- Shanghai Unicom → Tokyo IIJ: Approx. 28ms
- Shanghai Mobile → Tokyo IIJ: Approx. 26ms
- Beijing Telecom → Tokyo IIJ: Approx. 58ms
- Guangzhou Telecom → Tokyo IIJ: Approx. 44ms
If the latency measured in your local environment significantly exceeds the above range, it indicates a possible detour or poor line quality.
Second Challenge: Traceroute/MTR Route Tracing – Understanding “How It Goes”
Low latency does not necessarily mean a good line – the key is to understand “how it goes.” Traceroute can trace every routing node a data packet passes through from your computer to the server, helping you determine if there are any detours.
Windows systems use `tracert -d test IP`, Mac/Linux systems use `traceroute -n test IP`.
However, Traceroute only performs a single tracing, making it susceptible to transient fluctuations. MTR (My TraceRoute) is highly recommended – it combines the functions of Ping and Traceroute, continuously probing each node along the route and providing statistical information.
After installing MTR, execute:
mtr -rw test IPWhen observing the output, pay close attention to: whether there is a 59.43 node (a characteristic of CN2 lines, generally not present on IIJ lines), whether there are obvious detour nodes (e.g., passing through the US and then back to Japan), and whether the packet loss rate for each hop is abnormal.
Taking a typical IIJ line as an example, the outbound routes for the three networks each have characteristics:
- China Telecom users: Via the 163 backbone network, aggregated through the IIJ backbone network, and then access Japan.
- China Unicom users: Directly connected via the AS4837 international backbone network, connecting to the IIJ link.
- China Mobile users: Directly connected via the CMI backbone network, accessing through the IIJ international interconnection node.
If a large number of non-Asian nodes appear in the route (e.g., detouring through the US), it indicates questionable line quality.
The third challenge: Bandwidth and speed testing – verifying "how fast it can run"
After passing latency and routing tests, the next step is to verify the actual bandwidth.
Speedtest test: Install the Speedtest CLI on the server to test upload and download speeds to domestic nodes. Note: Tests should be conducted during both daytime and peak evening hours (8:00 PM - 11:00 PM) to compare the differences between the two time periods. A larger difference indicates a higher degree of bandwidth sharing and more severe congestion during peak hours.
iperf3 test: A more professional bandwidth testing tool. Run `iperf3-s` on the server and `iperf3-c serverIP` locally to measure the true upper limit of TCP throughput.
Taking Jtti Japan Light Cloud as an example, it provides 200Mbps optimized dedicated bandwidth and 1TB monthly traffic. In actual testing, the bandwidth consistently reached the advertised value, which is considered "sufficient" compared to similar products.
The fourth hurdle: Packet Loss Rate and Peak Performance – Determining Usability
Many VPSs perform perfectly during the day, but their true capabilities are revealed at night. Peak hours (8:00 PM - 11:00 PM) are the true litmus test for IIJ lines.
One of the advantages of IIJ lines is their ample bandwidth reserves, resulting in less network congestion during peak hours. Real-world testing shows that IIJ lines can keep packet loss rates low during peak hours.
It is recommended to continuously monitor with MTR for at least 30 minutes during peak hours to see if the endpoint packet loss rate consistently exceeds 1%. If the peak packet loss rate exceeds 2%-3%, this VPS is essentially unusable during peak business periods.
Additional Item: IP Purity Check
If you plan to use this VPS for cross-border e-commerce, managing social media accounts, or unlocking streaming media, IP purity is crucial.
You can check the following:
- Visit `ipinfo.io` to check the IP address's location and ISP information to confirm if it's a native Japanese IP.
- Test the unlocking status of services like Netflix, Disney+.
Jtti's Japan IIJ VPS uses native Japanese IPs, enabling the unlocking of mainstream services.
Jtti Japan IIJ VPS: A product worth your time to test.
Jtti (JT TELECOM INTERNATIONAL PTE.LTD) is a global network infrastructure service provider headquartered in Singapore. Its Japan IIJ line VPS is deployed in a Tokyo data center.
In terms of core configuration, Jtti Japan Light Cloud provides 1 core, 1GB memory, 50GB SSD, 200Mbps optimized dedicated bandwidth, and 1TB monthly traffic, supporting lifetime recurring discounts—the renewal price is the same as the initial purchase price, without the "low price in the first year, double the price in the second year" tactic.
Regarding network, all three major internet providers connect directly to Japan from their domestic network ports, without using third-party relays. The high quality of the IIJ backbone itself ensures the stability of global exports. If you're looking for a Japanese VPS with balanced bandwidth across all three major networks, ample bandwidth, and no price increases upon renewal, Jtti's IIJ lines are worth serious consideration.
In conclusion: Spend 30 minutes testing to save 300 days of hassle.
Before buying a VPS, spend 30 minutes conducting a complete test—ping for latency, using Traceroute/MTR to check routing, using Speedtest/iperf3 to verify bandwidth, and testing packet loss during peak hours—these four steps can help filter out 90% of unreliable providers.
Remember this: testing IPs isn't just a formality; it's your legitimate right as a user. Reputable service providers not only publicly provide test IPs but also encourage you to test them. If a provider is unwilling to provide test IPs, or if the provided IPs show numerous problems—pass immediately, without hesitation.
