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Advanced iRules: Scan

Scan is used to parse out strings. It takes a string and based on your format parameters, stores the matches in one or more variables. It also returns the number of conversions performed, so it can be used in a conditional as well. For all the... Read more
1 Review

Intermediate iRules: Evaluating Performance

Customers frequently ask, as poster CodeIT did: "I am wondering what the effect of writing more elaborate iRules will have on the F5’s memory and processor. Is there a way to predict the effect on the F5’s resources for a given rule and... Read more
0 Reviews

Intermediate iRules: Validating Your Logic

Sometimes an iRule will load and run without producing any errors, but does not achieve the desired results. In this article, I will outline the basic process of examining your iRule logic against live traffic by walking through a simple example:... Read more
0 Reviews

Intermediate iRules: Data-Groups

For this article in the Intermediate iRules series we’ll begin arming you with some knowledge on data-groups. As such, this article will endeavor to answer the following: What is a data-group? What is a class? What are the benefits of a... Read more
0 Reviews

Intermediate iRules: Handling Lists

We've talked about variables in the Getting Started with iRules series, but we're going to cover specifically the list object type of variable. Most of the TCL commands for use in manipulating lists are available in iRules: list - Create... Read more
0 Reviews

Intermediate iRules: Iteration

In this article, we're going to cover loop control structures and how to gain efficiency therein. One of the things that makes iRules so powerful is the fact that it is effectively a full scripting language at your fingertips with which you... Read more
0 Reviews

Intermediate iRules: catch

One of the often overlooked features of iRules is the ability to use dynamic variables in assignments. This can make for some interesting iRules, but it can also get you into trouble at runtime when your variables are not defined in the current... Read more
0 Reviews

Intermediate iRules: Handling Strings

To say we’re getting to the heart of the matter, dealing with string commands and parsing, re-arranging and modification, would almost be saying it too lightly…understating. String manipulation is a massive part of iRules, and is in fact a solid... Read more
0 Reviews

Getting Started with iRules: Delimiters

So far in this series we've covered introductions across the board for programming basics and concepts, F5 terminology and basic technology concepts, the core of what iRules are and why you'd use them, as well as cornerstone iRules... Read more
0 Reviews

Getting Started with iRules: Events & Priorities

As this series steams on we go deeper and deeper into what actually drives iRules as a technology. So far we have covered very basic concepts, from core programming ideas and F5 basic terminology through to what makes iRules unique and useful,... Read more
1 Review

Getting Started with iRules: Variables

If you've been following along in this series, it's time to add another building block to the framework of what iRules are and can do. If you're new, it would behoove you to start at the beginning and catch up. So far we've covered... Read more
Average Rating: 4.9
3 Reviews

Getting Started with iRules: Control Structures & Operators

So far in the first several installments of this series we’ve talked about some solid introduction topics, from programming basics to F5 terminology to covering an introduction of what iRules is as a technology, how it works, and how to make use... Read more
Average Rating: 4.9
3 Reviews

Getting Started with iRules: Directing Traffic

The intent of this getting started series was to be a journey through the basics of both iRules and programming concepts alike, bringing everyone up to speed on the necessary topics to tackle iRules in all their glory. Whether you’re a complete... Read more
Average Rating: 4.9
5 Reviews

Intermediate iRules: High Speed Logging - Spray Those Log Statements!

High Speed Logging has been around since version 10.1, and has been integral to many projects over the past few years. Prior to HSL's introduction, logging remotely was configured entirely in syslog or could be handled in iRules by specifying... Read more
2 Reviews

Advanced iRules: Getting Started with iRules Procedures

As Colin so eloquently puts it in the procs overview in the iRules wiki: "Ladies and gentlemen, procs are now supported in iRules!" Yes, the rumors are true. As of BIG-IP version 11.4, you can move all that repetitive code into... Read more
Average Rating: 4.9
9 Reviews

Intermediate iRules: Clarifying IP::tos command usage

The IP::tos command has been around since the v4 days, and there has been some confusion on IP tos versus DSCP. The command takes the supplied value (or returns  a value) and applies to the tos field overall, which is eight bits. So if yo... Read more
0 Reviews

Intermediate iRules: String Handling Exercise

I had the privilege of watching an exercise in string handling unfold on an internal list recently that should have its day in the community. The Problem URLs for this particular application arrive in this format:... Read more
1 Review