Bandwidth Sizing/Capacity Planning

Hosting
1

I am sure this thread will be helpful to many newbies and even those not yet running extremely popular sites (if people repond):

Anyone have any tools/calculators (online or otherwise) or even fairly accurate guidelines for sizing one’s predicted bandwidth consumption for a month? Also, based on these figures how to extrapolate what size connection type one would need if they hosted themselves (i.e. to see if a T1, fract. T1, business-class broadband would suffice or whether one would have to host in a data center with better connectivity)?

Say for 5,000 pageviews/day. 30k average page size
Say for 25,000 pageviews/day. 30k average page size
Say for 125,000 pageviews/day. 30k average page size
Say for 250,000 pageviews/day. 30k average page size

I can ballpark figures for bandwidth consumption per month for just the pageviews but what sort of percentage of bandwidth calculations do you have to attribute to protocol/handshaking overhead and other services such as DNS (E-mail will be fairly minimal for me). Is there a rule-of-thumb for this?

Also, based on one’s need for monthly bandwidth, say 5G, 25G, and 250G, how can one relate that to conncection type size and determine when one needs to host at a data center that has the bigger pipes (T3, OC12, etc). Have not done much in regards to network capacity planning (enough to be able to have guessing be fairly accurate - i.e. not enough scenarios to feel comfortable with my current guesstimating).

  • Can people post their avg pageviews per day/month (state which), rough average page size (including graphics but considering caching), and the bandwidth they typically consume in a month. People posting info on this paragraph should state they are a “webmaster/site owner”.

  • Others with network capacity planning expertise: can you relate some of these scenarios to the various network connection types available and what they could handle (or provide links to such material)? Something like “a full T1 (1.54Kbps) can successfully handle XXXXXX pageviews/month for an average page size of YYYYY with extraneous services (DNS, etc.) figured in”. People attempting to post info on this paragraph should state what they base their knowledge off of (i.e. experience, job duties, I.T. education/certs, or ???) to give merit to their claim.

When I mention bandwidth consumption, I am not talking about point-in-time speeds of the connection type (such as 1.54Kbps), but more along the lines of monthly usage as hosting providers use in their hosting packages.

The only thing I have found thus far is:

“The usable bandwidth of a T1 circuit is 1.536 Mbps. There are 8 bits of
overhead. Your TCP/IP overhead would be added to that I believe. The number
I have seen tossed around for a "monthly" transfer on a T1 (and I only
assume it is correct because no one ever challenges it) is 350GB a month.”

Bursting could be an issue for these smaller ‘pipes’.

TIA!

2

To work out data transfer requirements for a website is really quite easy.

There are
1024 B to a KB,
1024 KB to a MB,
1024 MB to a GB

So a page of 30KB (total page content) which receives 5,000 page views per day would use (30/1024) * 5000 * 30 MB of data transfer per month.

Some common pipes used by data centers are (in Mbps - mega bits per second):
GE - 1,000 mpbs
OC12 - 622 mbps
OC3 - 155 mbps
FE - 100 mbps
DS3 - 45 mbps

The issue with most major colocation data centers (which is what most hosting companies use) is not the speed of their pipes out, but rather the speed of the network within the data center - most noticably the speed that the individual server is connected to the switch at. As you can see from the table below a server with modest requirements may only require a connection at 128 Kbps. However, a standard shared hosting server these days should be connected at somewhere between 1 and 10 Mbps. In the table below I have assumed that we want our network connection to burst to three times the average data transfer rate. This is probably a bit low - a factor of 5 might be more desirable.


Page 	Views	MB		Av 	B 	Pipe
Size	Per	Per		Kb/s	Factor	Speed
KB	Day	Month				Kb/s
30	5000	4,395 		14 	3	 41.67
30	25000	21,973		69 	3	 208.33
30	125000	109,863		347 	3	 1,041.67
30	250000	219,727		694 	3	 2,083.33
3

Good reply. I think the thing I was not coordinating in my thought process was to figure out an average bits per second WITH a reasonable burst multiplier figured in. I was leaving out the burst multiplier and that was what was making me mistrust my figures a bit. I think I overthought this a little! :slight_smile: Also, thanks for working it from the ground up for all to benefit. I should have done the same for all of that but the burst multiplier figured into the average (since I was missing that component). :tup: