Running an iPerf3 Server: Daemon Mode, Ports, and Logging
Foreground vs daemon mode, the one-test-at-a-time busy error, multi-port servers, systemd units, and the firewall rules an iPerf3 test server actually needs.
Latest posts — page 26
iPerf2 vs iPerf3: Differences That Actually Matter
Two tools, not two versions: they do not interoperate, flags collide, and each wins different jobs. Real output from iperf 2.2.1 and 3.18 shows exactly where they differ.
iPerf3 Parallel Streams and TCP Window Size (-P and -w)
Why fast links benchmark slow: bandwidth-delay product, a real 78% throughput collapse from a 64K window at 104 ms RTT, and how parallel streams buy it back.
iPerf3 UDP Testing: Bandwidth, Jitter, and Packet Loss
UDP mode measures what TCP hides: loss, jitter, and reordering. Real lab captures show a clean test, a 29% loss over-drive, and how to find the loss knee on any path.
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How to Use iPerf3: Commands and Examples From a Real Lab
Learn iPerf3 from install to JSON automation, with every output block captured live from a routed Cisco lab - including how to actually read Retr, Cwnd, and sender vs receiver lines.
Network Engineer Interview Questions & Career Guide (2026)
The technical and behavioral questions network engineer interviews actually ask, with strong answers, 2026 salary bands, career paths after CCNA, and resume keywords that pass the ATS.
Ping Sweep: Finding Live Hosts With Bash and Nmap
Find every live host on a subnet with a bash one-liner, and when to reach for nmap -sn instead. Why a down result never means the address is free.
Linux Ping Options Every Network Engineer Should Know
The iputils ping flags engineers actually use: -c/-i/-q for jitter, -s/-M for MTU, -D for timestamps, and the -I flag that fixes confusing IPv6 failures.
Testing MTU With Ping and the DF Bit
Find the path MTU with nothing but ping, from Linux and IOS XE, against a real 1400-byte link. The 28-byte math and the PMTUD black holes that hang TCP.
Cisco Extended Ping and Response Characters Explained
Source interfaces, the DF bit, repeat counts, and the response characters (! . U M) that tell you exactly what failed. Extended ping on Cisco IOS XE, captured live.
Ping Timeout vs Destination Unreachable: Decoding Every Failure
Silent 100% loss and Destination Unreachable are different failures pointing at different problems. Every ping failure message decoded with live lab captures.
How Ping Works: The ICMP Echo Exchange Explained
What actually happens between typing ping and the reply line, decoded field by field on a live 3-hop Cisco lab: ICMP echo, TTL, RTT, and jitter.