Wednesday, January 23, 2008

How To Calculate Data Transfer And Bandwidth Requirements

Calculating your data transfer needs, the associated bandwidth and its effects it will have on hosting your web site can be anything from easy; but it is one of those calculations that you'll need to do at some point if you want to make sure that you won't be stung with unexpected costs.

There are various problems associated with calculating your data transfer and bandwidth requirements. How do you account for cached pages and images? What size unit does the host use for their calculations, and how can your bandwidth limit affect the quality of your hosting?

Be Careful

Not all data transfer limits are created equally; units of measurements can vary between hosts and if they don't make it clear be sure to ask them how many bytes per kilobyte they used when drawing up their comparison tables.

Caching and it's Effects on Data Transfer

Many ISPs use proxy servers to help speed up Internet access for their customers. The idea is that these servers keep a copy of your page on the proxy server (for a certain amount of time), and update their copy as you change your page. The effect of this is that while your page may have only be downloaded from your server once, it may have been seen by a number of people.

If you have static pages that rarely change, then caching can go some way to reducing your hosting bill. Clever use of meta tags can tell the browser not to bother reloading the page from the server if it is available on the users computer or a proxy server. Since these revisited pages do not have to be reloaded from your server, a single page request in your logs could equate to several-hundred page views for that page (particularly if you were paid a visit from a large proxy server used by some of the bigger ISPs).

Dynamic pages are not so suited to caching, but if the dynamic elements of pages are not visitor or time sensitive, then caching can be used to some degree to keep that data transfer bill down; for example, a page using the date may only need to be built by the server once each day. In the case of building dynamic pages, caching can also be used to reduce the server load by storing results of database queries in the server cache.

Bandwidth and the Quality of Hosting

When looking for a suitable host, be sure to check out the amount of bandwidth that will be available to your site. Even a site that does not require a great deal of data transfer per month could run slow if you are hosting on a shared server; particularly if you are on the same server as a more popular or bandwidth intensive site.

The more sites hosted on a server, the more likely they are to compete with each other for available resources; including bandwidth. This is why you may notice a slow down in server response times during busy periods, or a sudden peak in traffic at a busier site on a server you are sharing.

Redundancy Matters

How much bandwidth is left unused at any time to allow for sudden peaks in traffic is known as redundant bandwidth. The more redundant bandwidth a particular server has, the better it is likely to cope with sudden peaks in traffic; which can make all the difference between a pitiful and a successful site advertising campaign.

If your site is consistently slow and busy (particularly at set times during the day), then it could certainly benefit from having more bandwidth. The chances are your host does not have enough redundant bandwidth to deal with normal demand; they may need to upgrade their bandwidth capacity or simply review their bandwidth management strategy.

Ideally any host you are considering should have connections to the backbone with at least two service providers and at least 25% redundancy in all its connections. The higher the number of connections, service providers and percentage of redundancy, the better it will cope when things get busy or are unavailable.

Bursting the Bandwidth Barrier

By looking for a plan that allows for burstable bandwidth, you will be going some way to prevent slowdown experienced by your visitors during peak traffic periods. All burstable bandwidth means is that you can use more bandwidth than your hosting plan would normally allow, should you need to; which is extremely handy should the flow of traffic coming and going from your server suddenly peak. Note that the additional bandwidth available to you will depend on the level of the redundant bandwidth in the backbone connections your site has access to.

Hosts that offer burstable bandwidth with your package will let you make use of some (or all) of the redundant bandwidth to help your site cope with the traffic. It would be worth pointing out that it should only be used as a short term solution; since if you are consistently utilizing more bandwidth than your hosting package allows, you really ought to upgrade.

Serving Large Files and Multimedia

If you hadn't guessed already, bandwidth availability can go a long way to determining both the quantity and quality of site downloads; whether they be large archives or multimedia presentations. As access to the server becomes more difficult, the number of packets lost increases. For small files, such as web pages and images, this isn't such a problem; packet loss is (statistically) less likely to occur on small files. On the other hand, larger files are more likely to loose data during transfer since there are more opportunities for packets to become lost. These lost packets can adversely affect the quality of the download. Files can become corrupted; streaming media gets jitterier the more data is lost.

If you intend to host downloads or multimedia files on your site, it is worth shopping around for a host with plenty of bandwidth, data transfer and a good level of redundancy in its connections to the backbone. Having a server that can support resume if serving large files is useful for saving unnecessary data transfer.

Your bandwidth and data transfer costs will make up the bulk of your hosting bill. While burstable bandwidth may be a luxury you could afford to do without, it is always a good idea to get as much bandwidth and redundancy as your budget will allow.

Bandwidth Resources

To help navigate through the decision process and emerge on the other side with the best solution for your business .... utilize the free services from Business Bandwidth

If your application is more residential in nature use this tool to help find the right bandwidth solution .... Residential Bandwidth

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3 Comments:

Anonymous Andrew said...

hi,
I would like to know more about calculating bandwidth demand/requirement.

Are the models that I can based on?

My current problem is to calculate the minimum trunk bandwidth requirement to meet the demands of a group of LAN users. I've been searching high/low but I'm stuck...

Hope that you can help me please. Cheers!

pj_lee25@yahoo.com.sg

4:28 AM  
Anonymous 2O said...

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6:56 AM  
Anonymous 2O said...

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7:02 AM  

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