Solved

What exactly is meant by SSL Transactions Per Second ( TPS ) in an SSL offloading scenario?

Posted on 2008-06-24
4
9,407 Views
Last Modified: 2010-04-21
I'm evaluating content delivery / load balancing vendors and many measure their appliance's ability to perform by SSL Transactions Per Second or SSL TPS. TPS is higher when there is dedicated hardware to process SSL connections rather than just software (obviously). SSL certificates are installed or terminated on the device, the device negotiates with the client browser and typically the connection from the load balancer to the server is not encrypted.

I'm trying to determine our TPS needs based on our traffic and I don't have a clear way to translate, say requests/sec into SSL TPS. There doesn't seem to be a direct correlation.

Does TPS refer to ONLY the handshake? What happens if someone requests a secure web page with 50 references to images over HTTPS? Is that 1 plus 50 = 51 TPS?

Hutch
0
Comment
Question by:bigdork
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
4 Comments
 
LVL 33

Accepted Solution

by:
Dave Howe earned 250 total points
ID: 21864304
yes, that would be 51 transactions. you have to remember that the hard bit is the SSL handshake - you are using large-number math for the certificate validation step, plus for the PFS symmetric key negotiation. by contrast, the actual data traffic is trivial.

TPS is the number of ssl handshakes, regardless of bytes moved.
0
 

Author Comment

by:bigdork
ID: 21865275
Dave thanks for the reply. Just to muddy the question a bit - I was under the impression with TCP Multiplexing that those 51 requests/sec are reduced to a smaller number meaning I don't have as many TPS as I do GETS/Sec. The vendors usually have 2 stats they advertise "Reqs/Sec" and "TPS".

Perhaps to beat the horse here - so you are ultimately saying I should evaluate how many Requests/Sec I recieve over HTTPS and that should roughly be Transactions Per Second?

I appreciate it,

Hutch
0
 
LVL 33

Expert Comment

by:Dave Howe
ID: 21867028
With TCP Multiplexing then multiple SSL Transactions are initiated to the offloader/balancer, which then opens a single HTTP 1.1 connection to your backend server and serializes the requests from a single IP down that one channel. as this is usually truely http rather than https, this really only saves you one tcp setup/teardown - not to be sneezed at in today's high load environments, but still not a lot. the bulk of the savings are in offloading the crypto overhead onto the balancer. Of course, if the browser itself can handle TCP Multiplexing, then multiple requests may be bundled into a single ssl transaction before they reach the balancer.

in addition, many balancers (such as the F5 "big ip" device) are also caching servers - so for a number of seconds after an initial response for (for example) a gif, further requests for the same image would be satisfied from cache and not pushed forward to your backend content hosts
0
 

Author Closing Comment

by:bigdork
ID: 31470397
Thanks Dave - I appreciate your help on my question and also the follow up question on multiplexing as well.
0

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Every business owner understands the significance of online customer reviews and the impact it can have on sales and revenues. With technology advancing at such a rapid pace, getting online reviews has never been easier, especially when many regions…
Original post  on Monitis Blog. Web performance monitoring is broken into two camps: passive and active. Passive monitoring is defined as looking at real-world historical performance by monitoring actual log-ins, site hits, clicks, requests for …
Viewers will get an overview of the benefits and risks of using Bitcoin to accept payments. What Bitcoin is: Legality: Risks: Benefits: Which businesses are best suited?: Other things you should know: How to get started:
With Secure Portal Encryption, the recipient is sent a link to their email address directing them to the email laundry delivery page. From there, the recipient will be required to enter a user name and password to enter the page. Once the recipient …

752 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question