How to calculate MRTG bandwidth?

Thanks.

take the number shown, and devide by 8 for bytes/second, or the number as shown for bits/second.

Hmm Ic...

And so I calculated my month bandwidth...and it's only 274GB while I have 2TB of my server's bandwidth allowance...and its the end of month already.... LoL:smash:

Multiply the monthly average in KB/s by 0.33 and this will output the data transferred in Gigabytes, not %100 perfect calculation but averagely.

You're not going to want to use an average of the numbers that are displayed by MRTG, natively. Alternately, you'll want to obtain the 95.pl script from http://www.seanadams.com/95 and use the .95 figure for calculation.

You dont use 95th percentile to get average. If your provider charges you that way you are getting a bad deal. If you are getting billed on actual you deserve to have that based on actual not some calculation of 95th.

95th does not give you actual. It gives an estimate that is very much in the providers favor. Some providers try to justify this by saying it is the way they pay for bandwidth. The bottom line is it is not ACTUAL. It is what you would have used if you would have maintained your top 5% of usage for the entire month.

The answer to the original post is you calculate MRTG off data that your router or switch reports. These are actual numbers. So when you look at 5 minute average on a program like RTG, Cacti, etc the program takes the amount of traffic in that 5 minute period and tells you what the average is.

This is why I get so frustrated with people "calculating" actual from other figures like 95th. Actual is what is reported. Why manipulate it? The answer is that it inflates usage. Inflated usage means you pay for more than you actually used.

Remember when looking at MRTG that it is an average of 5 minutes on a daily graph. If you have a 10Mbps connection and see your usage at 8Mbps there is a good chance you are maxing out your connection. If you what real time stats off the router you will see it maxing out. Not always, but it happens.

You dont use 95th percentile to get average. If your provider charges you that way you are getting a bad deal.

It rather depends on what your traffic patterns are. If you have a choice between capped CDR (i.e. you pay for 10mbps capped), or 100mbps burstable with 10mbps @ 95th then most people who have bursty traffic will choose the latter. It is not automatically a bad deal, especially for people who may transfer tens of terabytes per month, so paying per-mbps bandwidth is much cheaper than per-gb of data transfer.

It is what you would have used if you would have maintained your top 5% of usage for the entire month.

No, that's not what 95th percentile is at all. It just means you get the 5% (36 hours worth) of your highest bandwidth usage free of charge, enabling you to burst instead of having a capped rate.

Some providers try to justify this by saying it is the way they pay for bandwidth.

Well, it usually *is* how they pay for their bandwidth ;)

Just FYI, I'm not trying to justify this over any other billing method. We provide all three common methods (per-gb data transfer, per-mbps capped and per-mbps 95%tile) to our customers and explain the differences so they can make an informed decision about which method will give them the best deal for their particular traffic pattern.

I was trying to simplify with the 5%. A lot of people really dont understand what 95th is and I really dont know how to make it simple.

My only disagreement is using 95th to come up with actual. That is not a precise measurement. The routers put out actual, so why not use that?

I also offer all three measurements. Usually one is better than the other for a customer. For instance, gamers usually want "actual." I am just totally against those that use 95th to calculate actual. When you call it "actual" you should use actual.

Oh yes - it would be totally unfair to calculate the 95%tile usage and say that the value you get is the "actual" usage...