A Repeatable Network Troubleshooting Method That Saves Time
A practical workflow for isolating network faults without bouncing randomly between devices, tools and theories.
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Network Engineering Guides
Practical references for troubleshooting, routing, switching, fiber, IP addressing and NOC operations. The focus is on what to check, what the evidence means, and how to verify the fix.
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Featured troubleshooting guides
Three practical references for common faults that benefit from a structured approach.
Low Receive Power on Fiber: A Practical Isolation Guide
Troubleshoot weak optical receive levels by working from measured loss instead of swapping parts at random.
BGP Session Down: A Practical Troubleshooting Sequence
A structured checklist for BGP neighbors that are Idle, Active or repeatedly resetting.
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IPv4 Subnetting Without the Guesswork
A practical guide to network addresses, masks, usable ranges, broadcast addresses and choosing the right IPv4 subnet size.
CIDR and Route Summarization in Real Networks
How CIDR blocks, longest-prefix match and route summaries work together, with practical checks for overlap and unintended reachability.
Planning IPv4 Address Space with VLSM
A practical way to allocate differently sized subnets, reduce waste and leave room for growth without painting the network into a corner.
IPv6 Addressing: A Practical Operations Guide
How to read, compress, expand and plan IPv6 prefixes without getting lost in 128-bit notation.
OSPF Cost: What the Number Really Changes
A field-focused explanation of OSPF interface cost, reference bandwidth and safe path-engineering practices.
Reading BGP AS Paths During Troubleshooting
How to read AS_PATH, understand prepending and avoid assuming that the shortest path is always the selected route.
How to Build and Read an Optical Power Budget
A practical guide to transmitter power, receiver sensitivity, fiber attenuation, connector loss, splice loss and engineering margin.
dBm, dB and mW: The Difference That Matters
A clear explanation of absolute optical/RF power versus gain or loss, with quick reference examples for network engineers.
SLA Availability and Downtime: Read the Fine Print
How availability percentages translate into minutes, what usually counts as downtime, and how to avoid misleading SLA reports.
MTTR and Incident Metrics That Actually Help a NOC
How to use mean, median, volume and outliers together instead of reducing operational performance to one number.
A Repeatable Network Troubleshooting Method That Saves Time
A practical workflow for isolating network faults without bouncing randomly between devices, tools and theories.
Interface Down? Work the Problem in the Right Order
A layer-by-layer checklist for troubleshooting physical and logical interfaces that will not come up.
How to Track Down Intermittent Packet Loss
Turn brief packet-loss complaints into measurable evidence and a smaller fault domain.
High Latency Troubleshooting: Find Where the Delay Starts
Separate propagation delay, congestion, routing changes and endpoint delay without guessing.
CRC Errors and Interface Counters: What to Check First
Interpret rising CRC and physical-layer counters without replacing hardware blindly.
MTU Problems: Troubleshooting Fragmentation and Black-Hole Paths
Recognize MTU mismatches, oversized frames and path-MTU discovery failures.
DNS Troubleshooting Tips for When “The Network Is Down”
Separate DNS failures from connectivity, application and routing problems quickly.
BGP Session Down: A Practical Troubleshooting Sequence
A structured checklist for BGP neighbors that are Idle, Active or repeatedly resetting.
Route Flapping: Find the Source Before It Spreads
Isolate unstable routes, interfaces and routing adjacencies before repeated changes impact the network.
OSPF Neighbor Stuck? Use the State to Narrow the Cause
Troubleshoot OSPF neighbors stuck in Down, Init, ExStart, Exchange or another incomplete state.
Asymmetric Routing: When One Direction Tells a Different Story
Recognize return-path differences and determine when asymmetry is harmless or the source of an outage.
VLAN Trunk Troubleshooting Without Guessing
A focused checklist for missing VLANs, native VLAN mismatches, tagging problems and trunk path failures.
LACP and Port-Channel Troubleshooting Tips
Diagnose missing bundle members, suspended links, hashing surprises and inconsistent port-channel state.
DHCP Troubleshooting: Follow the Address Request
A practical workflow for clients that cannot obtain an address or receive the wrong DHCP information.
Low Receive Power on Fiber: A Practical Isolation Guide
Troubleshoot weak optical receive levels by working from measured loss instead of swapping parts at random.
Dirty Fiber Connectors: Small Contamination, Big Problems
Recognize connector contamination and avoid repeated optical faults during troubleshooting.
Optical Transceiver Troubleshooting: Before You Replace the SFP
Check optics, compatibility, power and fiber before declaring a transceiver failed.
Packet Capture Tips: Capture Less, Learn More
Plan a packet capture so you get useful evidence without drowning in unrelated traffic.
Broadcast Storms and Layer 2 Loops: Fast Containment and Safe Recovery
Recognize a Layer 2 loop, contain the blast radius, and restore service without creating a second outage.
Something Broke After Maintenance: Compare Before and After
Separate expected convergence from a real post-maintenance fault by using the change boundary and saved pre-checks.
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