Load Balancing Digest

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. [...]

I think there are many people confused with the term “web switch”. I was definitely one of them, so I think it might help to explain what the term means.
Part of the confusion for the term “web switch” stems from the fact that many Layer 7/web switch devices also act as a Layer 2 [...]

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 [...]

Back when load balancers were the toast of the town, there were two competing methods for GSLB (Geographic Server Load Balancing). The first method was through use of DNS (and perhaps some IP or HTTP redirection), and the second was to use some type of routing protocol, such as BGP.
Today, pretty much everyone involved [...]

There was a recent post on the lb-l mailing list which discussed a problem relating to combining SSL and non-SSL virtualJerry o the free nextel free cingular ringtones download polyphonic ringtone. services pointing to the same web server(s).
The issue comes up when you have two virtual services, typically for the same website, one for [...]

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.
 

 
 
Number 1: Get Your Sniffing In Order
Take some time to [...]

You’re stumped. There’s a problem with your infrastructure, and you’re not positive what it is. You checked a few things out, but the symptoms befuddle you. You’re pretty sure it’s not the load balancer, but everyone is pointing at you, and you’ve got no proof.
What do you do?
I’ve been in that situation [...]

When I’m diagnosing load balancing issues, there are three really critical tools I use:

TCPDump
HTTP Header dump (such as Live HTTP Headers)
Telnet

Yup, telnet. I don’t know about anyone else, but I use telnet excessively. Basically, I use it to test TCP connectivity, and with a quick “GET /”, to test to see if the [...]