Actual Measurement Of Cn2 From Japan To The United States Compares The Transmission Performance Differences Of Multiple Nodes

based on actual measurement data, this article conducts a comparative analysis of key indicators such as delay, jitter, packet loss, and throughput of multiple cn2 lines from japan to the united states on different nodes. it points out the reasons for the obvious differences and gives executable testing and optimization suggestions to help engineers and operation and maintenance quickly judge link quality and select appropriate nodes.

by conducting ping and tcpreplay stress tests on five commonly used overseas nodes at the same time, it was found that the rtt of the cn2 link from japan to the united states fluctuated between 90ms and 170ms, with an average difference of about 60~80ms. for games and real-time voice, this gap obviously affects the experience; for file transfer or web page loading, peak bandwidth is more critical due to the impact of tcp slow start and bandwidth capping. during the test, jitter and the median of 50 samples were collected at the same time to eliminate misjudgments caused by instantaneous jitter.

within the same time window, some nodes experienced a packet loss rate of 0.5% to 1.2% under high-concurrency simulation, while the best-performing node had a packet loss rate of less than 0.1%. in terms of jitter, the jitter of the optimal node is maintained at 2~4ms within 1 second, while the jitter of the unideal node can reach 15~28ms. common factors that cause differences include congestion points on physical routes, interconnection strategies between operators, and protection switching frequencies of intermediate optical cables, which will be reflected in icmp and udp measurements.

a fair comparison requires unified testing tools and configurations: it is recommended to use iperf3 for throughput, mtr or traceroute to analyze paths, ping to measure delay statistics, and use tcpreplay to simulate real traffic. each node conducts at least three sets of tests in different time periods (peak, off-peak, and night), with each set lasting 5 to 10 minutes to reduce transient errors. at the same time, record the bgp path, as number, link mtu and whether it has been through cdn or traffic cleaning, so as to eliminate interference from factors other than the network itself during comparison.

transmission differences are often concentrated in three types of locations: first, physical congestion at the outbound switching node and the landing point of the submarine optical cable; second, strategic packet loss or speed limit at the inter-operator backbone interconnection (ix); third, the last hop from the destination us entry point to the final computer room. through traceroute, you can quickly locate the delay jump point; combined with traffic mirroring and operator feedback, you can confirm whether it is a link quality problem or a limitation caused by traffic engineering policies.

although they are all marked as cn2 , the specific routing, bandwidth guarantee and interconnection partners (peering) of different operators or different access points of the same operator are not consistent. cn2 only indicates that it uses a newer backbone and priority routing strategy, but it does not guarantee consistent end-to-end performance. equipment load, link synchronization, submarine cable maintenance windows, and intermediate as caching strategies will all lead to performance differences under the same nominal rating.

prioritize nodes with direct connections or high-quality interconnection in the target area. when testing, focus on 99th percentile delay and packet loss, not just the average value. if you encounter high packet loss, you can negotiate with the upstream operator to adjust the traffic engineering or change the exit point. for critical services, you can deploy multi-active lines and perform bgp policies or application layer switching to achieve nearby optimization. in addition, enabling tcp congestion control optimization, adjusting mtu, and performing traffic offloading can also improve transmission stability to a certain extent.