What Does a Switch Do? From MAC Address Learning to VLAN Forwarding
Follow source-MAC learning, destination lookup and VLAN forwarding. Distinguish unknown-unicast flooding, routing and loop protection when accepting an industrial switch.
Core, Aggregation and Access Switches: How to Plan Network Layer Roles and Capacity
Plan access, aggregation and core by traffic destinations, policy and failure domains. Check shared uplinks, merged-layer responsibilities and real redundancy dependencies.
OTDR Fiber Faults: Return Light, Events and Dead Zones
Read OTDR return light, trace events and dead zones. Use suitable launch/receive fibers and complementary loss tests before declaring a repaired fiber link acceptable.
How Ethernet Port Transformers Pass Signals Across Electrical Isolation
See how Ethernet transformers carry changing signals without direct winding contact. Distinguish isolation, differential rejection and equipment-level interference limits.
Industrial Network Pauses: How TCP Confirms Data and Why It Retransmits
Diagnose industrial TCP pauses using byte sequences, acknowledgments and recovery evidence. Separate transport receipt, application response and actual equipment completion.
Small Packets Work, Large Packets Fail: MTU, Jumbo Frames and Path Limits in Industrial Ethernet
Distinguish IP MTU, TCP MSS and Ethernet frame limits. Diagnose path-size failures and tunnel overhead with controlled length tests rather than assuming a speed problem.
Link UP but Stale Data: How Industrial Heartbeats, Timeouts and Watchdogs Detect False Online Status
Separate physical LINK, TCP reachability and fresh application data. Bind heartbeats to the monitored task and verify timeout, stale-value handling and staged recovery.
Industrial Ethernet Flow Control: How Pause Frames Ease Bursts and May Delay Control Traffic
Follow an 802.3x pause request from receiver to sender. Check supported directions, timing units, queue pressure and control-service delay before enabling flow control.
Industrial ARP: Address Resolution, Caches and Duplicate IPs
Trace ARP requests and replies within a VLAN. Separate endpoint IP-to-MAC caches from switch forwarding tables and preserve evidence when diagnosing duplicate addresses.
Industrial Ethernet CRC and FCS: Detecting and Locating Bad Frames
Separate CRC calculation, frame FCS and congestion drops. Use receive-counter changes and capture limits to investigate corrupt frames without guessing a failed device.
