nanog mailing list archives
Re: Teaching/developing troubleshooting skills
From: "Edward B. Dreger" <eddy+public+spam () noc everquick net>
Date: Sat, 26 Jun 2004 09:29:59 +0000 (GMT)
DG> Date: Fri, 25 Jun 2004 20:04:38 -0700 DG> From: Darrell Greenwood [ editted for brevity ] DG> The 5 day course can be boiled down really to one concept DG> that can be taught in 5 minutes... "binary search". Every half-decent programmer knows O(log(N)) is one's friend unless the scalar coefficient is large. A good way to demonstrate its efficiency is: * Have someone pick an integer between 1 and n, inclusive * Make guesses, going "higher" or "lower" according to the number-holder's feedback. The uninformed are surprised that one can always guess the number from 1 to 1000 in ten iterations or less. DG> The reason I am writing this note is as I went through a DG> career of troubleshooting I was surprised at the number of DG> colleagues who had no concept of "half-splitting" and used DG> "linear" or "random" techniques to determine test DG> points/tests with a corresponding dramatic reduction in DG> effectiveness. Good point. [ below text in response to nobody in particular ] It's also important that one avoid: * The faulty assumption there is but one problem * Incorrectly-formed causal relationships (NANOG-L has some examples of these) * Making too many changes in one iteration * Attempting to tackle a system with more unknowns than are absolutely necessary. A certain amount of troubleshooting can be taught, but IMHO it requires a self-driven person with intuitive reasoning. Finally: Apprenticeship. Have the novices follow along when experts work actual cases. A certain amount of troubleshooting is developing the intuition to make informed guesses -- e.g., "some idiot broke pmtud" -- and develop good leads without having to search methodically through the entire problem space. Eddy -- EverQuick Internet - http://www.everquick.net/ A division of Brotsman & Dreger, Inc. - http://www.brotsman.com/ Bandwidth, consulting, e-commerce, hosting, and network building Phone: +1 785 865 5885 Lawrence and [inter]national Phone: +1 316 794 8922 Wichita _________________________________________________________________ DO NOT send mail to the following addresses: davidc () brics com -*- jfconmaapaq () intc net -*- sam () everquick net Sending mail to spambait addresses is a great way to get blocked.
Current thread:
- Teaching/developing troubleshooting skills Pete Kruckenberg (Jun 24)
- Re: Teaching/developing troubleshooting skills Jon R. Kibler (Jun 24)
- Re: Teaching/developing troubleshooting skills Bruce Pinsky (Jun 24)
- Re: Teaching/developing troubleshooting skills Darrell Greenwood (Jun 25)
- Re: Teaching/developing troubleshooting skills Edward B. Dreger (Jun 26)
- <Possible follow-ups>
- RE: Teaching/developing troubleshooting skills Larry Pingree (Jun 24)
- Re: Teaching/developing troubleshooting skills John Neiberger (Jun 25)
- Re: Teaching/developing troubleshooting skills John Neiberger (Jun 28)
- Re: Teaching/developing troubleshooting skills Michael . Dillon (Jun 28)
- Re: Teaching/developing troubleshooting skills Bruce Pinsky (Jun 29)
- Re: Teaching/developing troubleshooting skills Eric Brunner-Williams (Jun 28)
- Re: Teaching/developing troubleshooting skills Michael . Dillon (Jun 28)