Load Balancing Digest

The ability for a load balancer to peer into (and potentially manipulate) the HTTP headers of incoming connections was once an advanced feature, but now is fairly commonplace.  Most often it’s used in cookie -based persistence, but it’s also used in web switching, true-source IP resolution, and other tasks.
But the ability to look at the [...]

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 the nasty little tendancy of routing all web traffic through a [...]

I realized that this was a dupe, but I think the topic is a little more effective.  Plus, I haven’t written anything in a while.  Every craftsman has their tools, and I’ve got three in particular that I use:

Telnet (Layer 4 TCP testing utility, Layer 7 interface)
OpenSSL (When Layer 4 is wrapped with encryption)
HTTP Analyzers [...]

EtherChannel is a strange creature.  It’s generally known as a way to load balance Ethernet traffic over multiple links.  Need more than 1 Gigabit of throughput, but don’t have 10 Gigabit interfaces yet?  Then bond two Gigabit links together in an EtherChannel link, and you’ve got 2 Gigabits.  That’s the idea, at least.  However, it’s [...]

It’s been about 6 months since the last load balancing/application delivery survey, so I think it’s high time we did another one.
So here’s your chance to contribute to the questions:  What do you want to know?  Put your suggestions in the comments section below, or email them to tony at lbdigest dawt com.

I dare say there are very few web servers left on the Internet. I think you’d have to spend a considerable amount of time trying to actually find one.
Now, given that you’re reading this on a web server, and there are obviously millions of websites, you may be asking yourself what the heck is [...]

There are a couple of terms in the realm of server load balancing (application delivery controllers) that can be somewhat confusing, because either there are multiple names for the same concept, or the same name means multiple concepts. I’m going to go over a few, to see if it helps clear things up a bit:
SNAT [...]

My recent Quick Look videos were inspired in large part by the highly hilarious “You Suck At Photoshop” series, which features 10 tutorials by the long-suffering Donnie Hoyle, Photoshop extrodinarre. But as I set about figuring out the logistics, one of the issues I had to consider was the bandwidth that would be used. [...]

Eight years ago I wrote an article called “It’s Always The Load Balancer“, and eight years later, that’s still the case. But despite being the undeserved scape-goat of an infrastructure’s (and society’s) ills, there are a few things that actually are the load balancers fault (and those who charged with their administration). And [...]

A great little tool for Windows systems is the command “netstat -e“. I shall explain.
A bane of of the network is the insidious duplex mismatch issue. This is when, through either autonegotion or auto-detection, one end of two cabled devices think the link is full duplex, and the other end thinks it is [...]