Load Balancing Digest

In my recent review of KEMP’s new LoadMaster software, which includes Web Application Firewall capabilities, Ofer Shezaf (from breach.com) had this to say in the comments section:
Systems supporting only snort rules and lacking a positive security model are not usually not considered a web application firewall, but rather an intrusion prevention system.
Which is an interesting [...]

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 [...]

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.

There was a post today on the lb-l mailing list asking about alternatives to Cisco’s CSS. This is part of a trend I’ve noticed lately, where people who have an existing Cisco CSS installation are looking to replace that gear with new gear.
Cisco CSS users specifically have an interesting choice when it comes 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 [...]

One issue that trips up people when diagnosing load balancer problems is they see a connection has been made to a virtual service, so it looks like they’re getting through to the real server.
That’s not always the case. Depending on how your load balancer is configured, it could simply mean you’ve made a connection [...]

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 [...]

You’re an application developer. You work in a world of untyped variables, debugging, and hitting reload over, and over, and over, and over again, all in the name of churning out a good web app. You can spot a SQL syntax error from the corner of your eye, and you’re the go-to guy (or gal) [...]

I got this email today from Don Keller in New Orleans regarding PHP interacting with a load balancer:
I read somewhere that the load balancer you run must support sessions, otherwise you must use cookies.”
This is a common type of question that people who are on the application development side of the [...]

I get a lot of questions on what’s the best load balancer to choose. There are currently over 20 vendors too choose from, so buyers can experience a little bit of over-choice shutdown.
So, here’s a few tips to help whittle down the vendors.
The first thing to consider is what type of company you [...]