Network Latency And Bandwidth Issues That Need To Be Paid Attention To When Renting A Server In South Korea And The United States

1. evaluation goals and indicators

before preparing to rent, clarify the usage scenario (web hosting, api, crawler, cdn back-to-origin, etc.); determine the key indicators: round-trip delay (rtt) target (for example, south korea - seoul to beijing, china ≤ 30ms, los angeles, usa to china ≤ 120ms), necessary peak bandwidth and number of concurrent connections; calculate bandwidth: bandwidth (mbps) ≈ concurrent connections × average throughput per connection (kbps)/1000, and then reserve 30% margin.

2. test line and node selection

practical steps: 1) ask the provider for the ip list and asn of the target computer room; 2) use ping -c 20 ip on the local or cloud host to measure the average rtt and record the jitter; 3) use traceroute/tracepath to check the hop count and packet loss points, and identify intermediate link bottlenecks; 4) repeat the test (peak/off-peak) in multiple time periods; compare data from different computer rooms to select sites.

3. notes on bandwidth specifications and billing

read the contract: confirm whether it is dedicated bandwidth or shared bandwidth; pay attention to the billing method (by 95th percentile, by peak value or fixed); if short-term bursts are required, choose a solution that can provide burst bandwidth or charge by traffic; require bandwidth guarantees and flow control strategy instructions to avoid being limited by traffic risk control.

4. use iperf/iperf3 for throughput testing

operation steps: 1) install iperf3 on the target server and start: iperf3 -s -p 5201; 2) execute iperf3 -c target ip -p 5201 -t 60 -p concurrency number on the local machine, record bandwidth, packet loss and retransmission; 3) test tcp and udp (plus -b parameter) respectively, adjust concurrent connections to observe the actual throughput; 4) save the log for communication with the provider.

5. optimize network configuration (system level)

specific operations: 1) adjust kernel tcp parameters (for example, set net.ipv4.tcp_window_scaling=1 and increase tcp_rmem/tcp_wmem in /etc/sysctl.conf); 2) check mtu to avoid fragmentation (ping -m do -s); 3) enable multi-queue and rss (network card support); 4) adjust file descriptors and epoll parameters for high-concurrency scenarios.

6. routing, bgp, and cdn cooperation strategies

recommended steps: 1) ask the supplier whether it supports bgp multi-line or backup lines; 2) consider cdn back-to-origin and nearby access when publishing services to reduce transoceanic traffic; 3) negotiate with the supplier to optimize direct links or submarine cable paths; 4) if it is a station group, disperse the computer rooms to reduce the impact of single-point delays.

7. monitoring and alarm deployment

practical operations: 1) deploy continuous monitoring (such as prometheus+grafana or zabbix) and collect ping, traceroute, and iperf scheduled task results; 2) set threshold alarms (rtt sudden increase, packet loss >1%, bandwidth utilization >80%); 3) save logs and generate reports regularly for optimization or appeal to operators.

8. question: how to quickly determine whether the problem is from the local computer room or the computer room to the target network?

answer: first perform ping/traceroute from the local computer room to the computer room, and then repeat the test on the same ip from a third-party detection node (such as alibaba cloud, aws/google's lightweight host); if the local to computer room delay is high but the third-party node is normal, the problem lies with the local isp; if multiple nodes are abnormal, it is a problem with the computer room or its upstream link, and the traceroute results can be sent to the computer room for operation and maintenance analysis.

9. question: which one is more suitable for the station group business, bandwidth 95th percentile or pay-per-traffic?

answer: for station group services, if traffic is stable and concurrency continues to be high, 95th percentile or fixed bandwidth is more cost-effective; if traffic fluctuates greatly and bursts occasionally, solutions that charge by traffic or support burst bandwidth are more flexible. before choosing, estimate costs based on historical traffic and allow for peak values.

10. question: after renting, it is found that packet loss is high and delay fluctuations are large. what should be the first step?

answer: the first step is to save evidence: continue ping/traceroute/iperf logs, mark the time window and take screenshots, and submit them to the supplier support in a timely manner; at the same time, temporarily switch to the backup line or cdn back-to-origin mode to reduce the impact; communicate with the supplier to request troubleshooting or replacement of the computer room/line.