The Operation And Maintenance Manual Diagnoses, Locates And Quickly Repairs The Cn2 Japan Delay

Introduction: This article is an operation and maintenance manual, focusing on operation and maintenance methods and executable processes. It provides diagnosis, positioning and quick repair processes for the CN2 Japan delay problem. The method in this article focuses on repeatability and verifiability, which facilitates rapid troubleshooting and recovery in a production environment.

Problem overview and scope of application

This section explains the scope of the problem: focusing on high latency or latency fluctuations on China Telecom's CN2 line to Japanese destinations. It is suitable for applications whose business is affected by real-time nature, such as games, voice, transactions, etc., and needs to be checked in a multi-operator and multi-BGP path environment.

Preliminary detection and data collection (ping/traceroute/MTR)

The first step is to collect delay samples: perform ping, traceroute and MTR on the target IP at different time periods, and record the round-trip delay, RTT of each hop and packet loss rate. Make sure to detect from multiple exit points and different PoPs to rule out local anomalies.

Key indicators and business impact assessment

Define and quantify key metrics: average latency, 99th percentile latency, packet loss rate and jitter. Map these indicators to business SLAs to evaluate whether it is an emergency work order or allow processing according to the regular change window to facilitate priority and resource scheduling.

Location steps: routing path and BGP inspection

Check whether the routing path takes the CN2 preferred link, and check the BGP routing table, AS path and next hop. Pay attention to whether there are path tracebacks, abnormal AS jumps, or community mark failures; compare historical route change records to discover recent policy adjustments.

Location steps: Packet loss, congestion and link quality analysis

Based on MTR and traffic mirroring, analyze packet loss and delay spikes at each hop to determine whether the problem is physical links, forwarding devices, or operator-side congestion. Combine interface utilization, queue length and QoS policy for in-depth investigation.

Quick Fix Process: Temporary Measures

When obvious link or routing problems are located, temporary measures should be taken first: adjust BGP local priority, deploy bypass tunnels, temporarily divert traffic, or switch cross-operator exits to ensure that service delays return to an acceptable range, and record operations for rollback.

Key points for long-term optimization and communication with operators

For frequent or long-term problems, open a work order to communicate with the operator and provide complete detection logs, routing information and traffic samples. It is recommended to negotiate BGP policies, adjust link bandwidth, or troubleshoot CN2 core node performance issues to promote root cause repair.

Change verification and monitoring alarm optimization

Regression verification after any fix: repeat ping/traceroute/MTR and compare to baseline. Improve monitoring and alarm rules, add automated detection of end-to-end delays, hop packet loss, and BGP routing changes, and set reasonable thresholds and notification mechanisms.

Summary and suggestions

Summary: The operation and maintenance manual's diagnosis, positioning and quick repair process for CN2 Japan delays should cover data collection, routing and link positioning, temporary detours and long-term collaboration, and should be combined with automated monitoring to visualize the problem. It is recommended to establish normalized detection scripts and fault drills to ensure rapid location and recovery in high-latency events.