100Mbps uplink for web hosting. How much traffic can I push?

A few years ago a fully-dedicated 100Mbps up-link for a dedicated server was a dream for many folks. Not anymore! The bandwidth pricing went down drastically, the internet connectivity speed has increased a lot.

Nowadays even a budget dedicated server has 100 Mbps up-link and the question is how much bandwidth you can push?

Let’s look at the typical scenario: a web server hosting a large web site or blog. Since we are interested in maximum bandwidth your server can push using 100Mbps up-link, we will skip the server CPU/RAM/IO load issues that usually is a quite big problem with many concurrent web visitors and popular sites.

100Mbps up link 100% used 24/7 can generate around 30TB bandwidth up and 30TB down from the server. This is of course the ideal condition and can’t be meet in real hosting environments (package loss, latency issues etc).

Web server most common patterns:

  • The most of the traffic is served “from” the server to web visitors, unless you run a very specific web site service (e.g. clients uploading large image or CAD files) or your site is receiving flood / attack.
  • There are specific peak times (increased web visitors) depending on your site content, targeted visitors, when new content is published etc..

From my own experience peak-time traffic can be very huge and sometimes, hard to predict. You never know when your amazing blog post or tech article will land on Digg or Yahoo! frontpage.

Let’s do a simple math and see some traffic levels for your web site. Assuming your web site front page with all the images are around 150KB in size.

KB – kilobytes
Kb – kilobits
MB – megabytes
Mb – megabits

10 concurrent web visitors accesing front page:

10 x 150KB = ~1500KB = ~1.5MB
100Mbps = 12.5MBps

Theoretically with 100Mbps link you can serve  around 80 web visitors (12.5MBps / 0.150MB = ~83 visitors/second). This is of course in ideal conditions.  Keep in mind that TCP/IP packages have own headers that generate little more traffic. Web server IO/RAM/CPU does affect server performance as well as OS, NIC etc.

While saturating 100Mbps up-link is no problem for today’s server, from my experience, I would say you will be OK serving 50 concurrent clients in parallel on 100Mbps up-link assuming page html with images are 150KB in size. This is a perfect scenario with static content serving. I hope this little post did provide some advice for you. Cheers!

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