#SDN #webperf It means you can't use "network" protocols to make intelligent decisions about applications any more.
Back in 2000 (or 2001, I forget exactly), I got to test a variety of bandwidth management appliances. Oh, they were the bomb back then - able to identify (and classify) applications by nothing more than an IP address and a TCP port. Once identified you could set quotas on bandwidth consumption and burst capabilities. It was quite the technology, back then.
But that was before applications all starting using HTTP as if it were TCP. Between the rapid ascent of the Internet as place to do business and the webification (remember when that was a thing?) of applications there are very few applications that don't rely on HTTP as their primary "transport" protocol.
What that means is that there are a whole lot of very different applications that use port 80 (or 443). You can't, by port, determine anything about that application except that, well, it's probably HTTP and definitely TCP. Is it video? It is text? Is it interactive? Dynamic? Static? An API?
Having just the IP and Port is like having a street and house number but not knowing who lives there or what's inside. You end up sending mail to "our friends at" or "current resident" because you have no clue as to who actually lives there. Your marketing and offers are general, they aren't tailored or specific, and you've no clue if you're even reaching the right demographic. Oh, your coupons are delivered, but if I don't shop at your store anyway, you just wasted several cents on me that you could have saved had you known better. And several cents times thousands (or tens of thousands) of coupon flyers is a lot of waste.
Sometimes you hit the right house and your message is well received and appreciated, it has a positive result. But it's hit and miss. More often than not, you wasted time, effort and money because you were blind.
That's how it is in the network, where reliance on TCP and port number wind up rarely hitting a home run in terms of positive impacts, and the rest of them time end up as wasted effort.
The implications go beyond classification.
It means that services like acceleration, optimization and security must be application-aware. They must be fluent in a given application's behavior and requirements in order to apply the right policy at the right time.
Which means anything operating at TCP or below isn't able to effectively do that. It means that without application layer (L4-7) services, you're pretty much out of luck in terms of how much you can leverage the network to impact the performance, availability and security of applications.
It means L4-7 is now critical, because it's only at those layers of the network stack that visibility into an application can be achieved and only at those layers can you execute the kinds of policies and functions needed today to make data centers more efficient and secure.
It means that without application-aware (and application-fluent) services your policies and processes in the network are executing either blindly or too broadly to have a real impact on the performance, reliability or security of a a specific application. It might be application-aware, but it's not application-fluent - or driven.