Category: Observability
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Performance Diagnostics Part 4 -HTTPS Performance
Unlike HTTPS, analysing HTTP traffic with tools like Wireshark is pretty easy because everything is in clear text. Wireshark will even give you the request performance (49ms highlighted below). I can also see that the request was sent in packet 4 (after the three way handshake), and the response came in packet 6. The delta…
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Top 5 Wireshark Tips for Network Analysis
I’ve been using Wireshark since it was named Ethereal back in the very early 2000s, and I still use it daily for research. Wireshark recently turned 25 with creator Gerald Combs announcing it on the Wireshark blog and celebrating it at Sharkfest ‘23 Asia and US. To celebrate I’m going to offer my top 5 Wireshark tips for 2023! Tip 1 — Use Profiles…
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Performance Diagnostics Part 2 — Revenge of the OSI Model
Continuing on from the previous article where I discussed an amalgamation of performance diagnostics with fat client applications. I thought it was a good time to go back to computer science 101 where we were introduced to the OSI model and the TCP/IP model. Both are models that some architectures and platforms more or less…
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Performance Diagnostics Part 1
Over the last 20 years I’ve been sent in by customers to investigate some of the most intriguing application performance problems that have had customers investing in infrastructure, time in war rooms, connectivity to try and resolve a problem that is eluding the technical team, or the technical team is unable to quantify what will…
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Initial Congestion Windows in Linux
As part of my research I’ve spent a lot of time looking the performance of TCP variants and options. One of the most common questions I get asked is about the congestion window and how it reacts to change in the environment. The congestion window (CWND) is used to control how many segments (layer 4…