Tech Notes Archive

  • Best of Both Worlds: Selective Source-NAT

    Best of Both Worlds: Selective Source-NAT

    Posted on March 11, 2009 | 1 Comment
    One of the most common issues that comes up is something often referred to as the “same subnet” problem.  In certain configurations, you cannot connect to a VIP (Virtual IP address, or Virtual Server) if the client you’re connecting from is on the same subnet...

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  • Quick and Dirty Performance Testing With Apache Bench

    Quick and Dirty Performance Testing With Apache Bench

    Posted on February 5, 2009 | No Comments
    If you need a quick and dirty way to throw some load onto a load balancer/ADC or web server, Apache comes with a great tool called Apache Bench.  Since it’s an HTTP client, it will of course work with any server, not just Apache-based servers....

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  • Mega Proxy Not So Mega, Akshually

    Mega Proxy Not So Mega, Akshually

    Posted on September 15, 2008 | 7 Comments
    Apologies for the LOLcatspeak.  I’m incapable of helping myself. The driving force behind Layer 7 persistence (keeping an individual user tied to a specific server in a server group based on HTTP headers instead of IP address) was the dreaded AOL Megaproxy issue.  AOL had...

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  • Linux.com Article: Load Testing

    Linux.com Article: Load Testing

    Posted on August 13, 2008 | No Comments
    I was doing my obessive-compulsive reloading of Digg’s main page, and came accross this article on load testing with open source tools.  Good read.

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  • Part-Time Regex’r? Regex Coach

    Part-Time Regex’r? Regex Coach

    Posted on April 21, 2008 | 2 Comments
    I deal with regex enough to need to know a beginning to intermediate level of knowledge, but I don’t use it enough to be able to form regex statements without thinking. Or in load balancing terms, it’s not burned into my brain ASIC. Every time...

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  • 4 Things You Can Do To Improve Your Load Balancing Infrastructure for 2008

    4 Things You Can Do To Improve Your Load Balancing Infrastructure for 2008

    Posted on January 21, 2008 | No Comments
    It’s a new year, and time for resolutions and all that. In that spirit, I’ve put together a list of 4 things you can do to improve your load balancing infrastructure. Some are quick, some are more involved, but they’ll all pay huge dividends.  ...

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  • The Importance of Diagnostic Tools

    The Importance of Diagnostic Tools

    Posted on August 8, 2007 | No Comments
    Diagnostic tools are critically important.  It’s something that often gets forgotten in product development, but it can make or break a product, especially in a product’s formative years (or during big code updates) while the kinks are being worked out. The swiss army knife of...

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  • Same Sunbet Problem

    Same Sunbet Problem

    Posted on May 8, 2007 | 2 Comments
    One of the most common problems that afflict load balancing situations is the “same subnet” problem. This is when a client tries to browse a Virtual Service/VIP from the same subnet as the real servers. Lately, I’ve seen this come up on the mailing list....

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  • Daylight Savings Time fix for older F5 BIG-IPs

    Daylight Savings Time fix for older F5 BIG-IPs

    Posted on March 7, 2007 | No Comments
    On March 1st, a user asked the asked a question about what they might do to fix the DST problem (Daylight Savings Time), since it’s changing this year, for older F5 BIG-IP systems that were out of contract and ineligible for code fixes. Steve Lothspeich...

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