When shopping for an SSL acceleration device, whether it’s integrated into a load balancer or a stand-alone device, I’ve noticed people tend to vastly overestimate their needs when it comes to TPS (Transactions per Second).
Users might balk at 1,000 TPS. After all, 1,000 SSL TPS just doesn’t sound like a lot. So how much is it, really?
To answer this, just do a simple calculation: Take the average page size and calculate the maximum number of TPS possible through a given connection (T1, 10 Meg line, DS3). I think you’ll find that the numbers are a bit surprising.
Let’s take a page size of 20K. That’s 20,000 Bytes, or 160,000 bits. Add about 10% for SSL overhead, and that gets you 176,000 bits. Take the example of a T1 line, at 1.5 Megabits per second. Divide 1,500,000 bits by 176,000 bits, and you get about 8.5. So in a T1 line, the maximum number of 8.5 TPS in a T1 line without over-subscribing the line.
- T1: 8.5 TPS
- 10 Mbps: 56.8 TPS
- DS3 (45 Mbps): 255.7
- 100 Mbps/Fast Ethernet: 568.1
- OC3 (155 Mbps): 880.7
- Gigabit Ethernet (1,00Mbps): 5681.8
So, as you can see, to get to really insane levels of TPS you either have to have a huge pipe, or you have to have insanely small pages.
How about the Size of the request in your example ?
Nowadays, HTTP requests from browsers can contain a lot of headers, and the HTTP request can be 1k and more