Recently, I posed a question on the mailing list: What do you call these devices that balance load and possibly do all this other stuff?
The reaction to such a seemingly innocuous subject was actually the most impassioned discussion the mailing list has seen in nearly 7 years of operation. Many of the vendors weighed in, and their position is fairly unified: They call these devices “application delivery devices/platforms/etc.”
There wasn’t much from the user side in this discussion, but I’ve talked with many, many users and load balancing administrators. In my day to day environment, I work with the premium products exclusively. On the side, in writing, and answering emails from various users, I primarily deal with the value market. In either case, the consumers, users, and the periphery (those that don’t deal with load balancers directly, but their operations are affected/serviced by load balancers), almost exclusively call these devices simply “load balancers”.
The vendors argument is understandable: These devices (especially from the higher-tier vendors like F5 and Citrix), do quite a bit more than just load balancing (although they still do load balancing). TCP multiplexing, application security, compression, caching/web acceleration, SSL termination, and they’ll babysit your kids.
But here’s my argument: While these devices do a lot more than what were first called “load balancers” from the late 90′s, but they’re still load balancers. They serve the same basic function (albeit with a lot more functionality) and sit in the same place in the network. The term load balancing is ambiguous, but so is application delivery. The difference is, most people know what load balancers are, and not many know what type of device the term application delivery entails.
Also, I don’t know of anyone who’s ever been confused by the term “load balancer”, thinking it meant a simple, Layer 4-only box. From feature-rich F5 to a Linux Virtual Server box, they’re both called “load balancers” by those that deal with the technology. If anyone has a need for any more specificity, they use the vendor’s name.
There really aren’t any Layer-4 only devices anymore. Even in the value market, where vendors are more likely to refer to themselves as load balancers, the devices perform Layer 7 URL parsing/switching, cookie persistence, and more.
So I understand the desire to differentiate, but the proposed terms are only slightly less ambiguous as the load balancer term, and are far less well known. So myself and others in the industry continue to call these devices “load balancers”.
