docs(notes): update 2025-03-20 traceroute output documentation

Author: lzwjava

notes/2025-03-20-traceroute-output-en.md

@@ -399,4 +399,145 @@ Each line represents a hop with three RTT (round-trip time) measurements in mill
 - **No Major Bottlenecks**: Unlike the international traces, latency stays low throughout, with no sharp jumps.
 - **ISP Behavior**: Consistent with prior traces—early ICMP filtering but reliable transit.
 
-If you want to explore further (e.g., test packet loss or use TCP mode), let me know!
+If you want to explore further (e.g., test packet loss or use TCP mode), let me know!
+
+---
+
+Let’s analyze the traceroute output to `n3twz3.mry.best` (resolving to `114.41.26.172`) step-by-step, examining the network path, latency, and key details.
+
+---
+
+### Traceroute Output Overview
+```
+traceroute to n3twz3.mry.best (114.41.26.172), 64 hops max, 40 byte packets
+```
+- **Destination**: `n3twz3.mry.best` (IP: `114.41.26.172`), hosted by Chunghwa Telecom (Hinet) in Taiwan.
+- **Max Hops**: 64 (maximum routers checked).
+- **Packet Size**: 40 bytes (standard for traceroute).
+
+Each line shows a hop with three RTT (round-trip time) measurements in milliseconds (ms). Asterisks (`*`) indicate no response from a hop for a given packet.
+
+---
+
+### Step-by-Step Analysis of the Hops
+
+#### Hop 1: `192.168.1.1`  
+- **IP**: `192.168.1.1`  
+- **RTT**: 3.957 ms, 9.621 ms, 24.882 ms  
+- **Explanation**: Your local router (e.g., home gateway). The private IP and variable latency (3-24 ms) are typical, with the spike possibly due to local traffic or processing.
+
+#### Hop 2: `172.16.0.1`  
+- **IP**: `172.16.0.1`  
+- **RTT**: 9.683 ms, 8.315 ms, 5.744 ms  
+- **Explanation**: Your ISP’s local gateway (private IP). Latency settles around 5-9 ms, normal for this step.
+
+#### Hop 3: `183.233.55.53`  
+- **IP**: `183.233.55.53`  
+- **RTT**: 7.914 ms, *, *  
+- **Explanation**: A public IP in your ISP’s network (likely China Telecom). Only one response suggests ICMP filtering or packet loss.
+
+#### Hop 4: `221.179.3.239`  
+- **IP**: `221.179.3.239`  
+- **RTT**: 18.088 ms, *, *  
+- **Explanation**: Another China Telecom router. Latency rises to 18 ms, with partial responses indicating filtering.
+
+#### Hop 5: `221.183.39.145`  
+- **IP**: `221.183.39.145`  
+- **RTT**: 18.512 ms, 22.371 ms, 20.114 ms  
+- **Explanation**: Stable hop in the ISP’s backbone. Latency is consistent at ~18-22 ms.
+
+#### Hop 6: `* * *`  
+- **Explanation**: No responses—likely an ISP router blocking ICMP. The trace continues, so connectivity isn’t affected.
+
+#### Hop 7: Multiple IPs  
+- **IPs**: `221.183.92.18`, `221.183.92.22`  
+- **RTT**: 15.532 ms, 17.851 ms, 11.492 ms  
+- **Explanation**: Load balancing within China Telecom’s network. Latency drops slightly to 11-17 ms.
+
+#### Hop 8: `221.183.55.81`  
+- **IP**: `221.183.55.81`  
+- **RTT**: 14.950 ms, 17.174 ms, *  
+- **Explanation**: Another backbone router. Latency remains low (~14-17 ms), with one packet dropped or filtered.
+
+#### Hop 9: Multiple IPs  
+- **IPs**: `223.120.2.77`, `223.120.2.85`, `223.120.2.101`  
+- **RTT**: 36.937 ms, 22.612 ms, 38.800 ms  
+- **Explanation**: Load balancing at a transit point (China Telecom’s regional backbone). Latency increases to 22-38 ms, suggesting a shift toward an external network.
+
+#### Hop 10: `223.120.3.90`  
+- **IP**: `223.120.3.90`  
+- **RTT**: 22.939 ms, 21.889 ms, *  
+- **Explanation**: Another transit hop. Latency stabilizes at ~22 ms, with one non-response.
+
+#### Hop 11: `223.119.21.178`  
+- **IP**: `223.119.21.178`  
+- **RTT**: 59.429 ms, 61.462 ms, 56.422 ms  
+- **Explanation**: Latency jumps to ~56-61 ms, indicating an international handoff (likely China Telecom’s exit to Taiwan).
+
+#### Hop 12: Multiple IPs  
+- **IPs**: `220.128.7.34`, `220.128.7.170`, `220.128.7.166`  
+- **Names**: `220-128-7-34.pcpd-4102.hinet.net`, etc.  
+- **RTT**: 56.696 ms, 66.389 ms, 54.760 ms  
+- **Explanation**: Entry into Chunghwa Telecom (Hinet) in Taiwan. The `.hinet.net` domain confirms this. Latency remains ~55-66 ms, consistent with a regional hop.
+
+#### Hop 13: `* * *`  
+- **Explanation**: Silent hop—likely a Hinet router blocking ICMP responses.
+
+#### Hop 14: Multiple IPs  
+- **IPs**: `220.128.13.49`, `220.128.13.17`  
+- **Names**: `220-128-13-49.chch-3032.hinet.net`, etc.  
+- **RTT**: *, 44.834 ms, 46.486 ms  
+- **Explanation**: Deeper in Hinet’s network. Latency drops slightly to 44-46 ms, indicating a stable segment.
+
+#### Hop 15: Multiple IPs  
+- **IPs**: `220.128.20.77`, `220.128.20.81`, `220.128.20.65`  
+- **Names**: `220-128-20-77.chch-3331.hinet.net`, etc.  
+- **RTT**: 69.628 ms, 46.463 ms, 53.779 ms  
+- **Explanation**: Load balancing in Hinet’s infrastructure. Latency fluctuates (46-69 ms), possibly due to internal routing or congestion.
+
+#### Hops 16-17: `* * *`  
+- **Explanation**: Silent hops—more Hinet routers filtering ICMP. The trace continues.
+
+#### Hop 18: `114.41.26.172`  
+- **IP**: `114.41.26.172`  
+- **Name**: `114-41-26-172.dynamic-ip.hinet.net`  
+- **RTT**: 58.726 ms, 72.539 ms, 56.788 ms  
+- **Explanation**: The destination! A dynamic IP on Hinet’s network in Taiwan. Latency stabilizes at 56-72 ms, typical for a regional connection.
+
+---
+
+### Key Observations
+1. **Path Summary**:
+   - Starts at your local router (Hop 1).
+   - Moves through your ISP’s network (Hops 2-10, likely China Telecom).
+   - Hands off to Chunghwa Telecom (Hop 12) and ends in Taiwan (Hop 18).
+
+2. **Latency Trends**:
+   - Low locally (3-22 ms in Hops 1-10).
+   - Jumps at Hop 11 (56-61 ms) due to the international shift to Taiwan.
+   - Stabilizes at 56-72 ms at the destination.
+
+3. **Asterisks (`*`)**:
+   - Frequent non-responses (Hops 3, 4, 6, 8, 10, 13, 16-17) indicate ICMP filtering by both ISPs, but connectivity remains intact.
+
+4. **Geographical Insight**:
+   - You’re likely in East Asia (China, based on `221.x.x.x` IPs).
+   - The destination is in Taiwan (Hinet’s `114.41.x.x` range and 56-72 ms latency suggest proximity).
+
+---
+
+### Comparison to Previous Traces
+- **Hong Kong (47.240.83.15)**: 35-40 ms (Alibaba Cloud).
+- **Taiwan (114.41.26.172)**: 56-72 ms (Hinet).
+- **Singapore (5.223.56.128)**: 110-130 ms (Hetzner).
+- **Helsinki (157.180.40.2)**: 250-260 ms (Hetzner).
+- **Insight**: Latency increases with distance—Hong Kong is closest, followed by Taiwan, then Singapore, and Helsinki is farthest.
+
+---
+
+### What This Tells You
+- **Network Health**: The trace completes with moderate latency (56-72 ms), indicating a reliable regional connection to Taiwan.
+- **Bottleneck**: The jump at Hop 11 (56-61 ms) marks the international link (e.g., China to Taiwan via undersea cable).
+- **ISP Behavior**: Consistent with prior traces—China Telecom filters ICMP early, then hands off smoothly.
+
+If you’d like to investigate further (e.g., packet loss or alternate protocols), let me know!