Realities of bandwidth billing

reactive-uk · 25th July 2008

I'm trying to compare like for like some quotes/ websites for colo and/or dedi servers, and trying to get it as like for like as possible. My questions are really regardign the bandwidth at this stage....

One thing that sticks out, especially on the colo side, is providors give an amount of 'guaranteed' (CDR) bandwidth - maybe 5-10Mbit per rack, then allow bursting, typically to 100M.

In reality then....

1) Does everyone charge the extra bandwidth consumed at 95%tile, or do many (as someone suggested to me) just forget about the extra 'as long as you dont take the mickey'. Conversely is charging all customers their 95% peak (and assuming these peaks dont occur together) actaully a good profit source for the hosts?

Is there such as thing as an average bandwidth curve (for an 'average' web server) that says 95% is x% of typical peak?

2) On dedi servers where they offer 999999Mbytes per month trafic on a 100Mbit port, I'm assuming that the actual max speed achieved depends to a great extent to how much they have oversold and what their upstream looks like ie I might get 50kbit dial up at the extreme!!

3) So to guarantee 100Mbit across my x (maybe 5) servers, I would need to buy that total requirement as a CDR and let my servers fight it out amongst themselves (or otherwise manage it?)

As ever thanks in advance!

JamesSykes · 25th July 2008

1. My experience is that most providers aren't mega strict on bandwidth. In that there is usually a small amount of leeway involved. One of my providers let me go over 2-3 months in a row because for the last 8 months it's been quite a bit under the CDR. But it really depends, some providers will bill you automatically and so there is no getting away from overages.

There is of course an average but that average probably wont be of much use to you or I or anyone else because every server is different. You can only look at your customer base and then plan from there.

2. Yes absolutely. For example if they are offering 10,000GB/month in bandwidth and you were to use ALL of that bandwidth you would be averaging something like 31 Mbits. It's obvious that there is some contention going on somewhere, it just depends on how their network is setup as to whether it will affect. Some providers will stick a 100mbit drop into a 24port switch and let them fight it out. Decent providers will run gig connections and make sure they have plenty of upstream bandwidth that their customers wont experience slow downs and just count on the fact that 90% of their customers won't do more than 5% of their allowance. (made up figures you get the idea)

3) To guarantee 100mbit you can just take a 100mbit drop and a low CDR. It all depends on what your usage is likely to be. You should keep your CDR as low as possible because otherwise it's just wasted bandwidth/money. It's probably better to be over a few mbit than under because that's money down the drain during those months.

JamieBeeston · 25th July 2008

You wont guarantee 100mbit just by getting your provider to give you a 100mbit port.. just as you wont guarantee 1000mbit by getting them to give you a gbit port.. if they dont have it to give you in the first place, you'll never get it... but I'll agree you're more likely to get 100mbit from a dedicated 100mbit port than not.

othellotech · 25th July 2008

Quote:

Originally Posted by reactive-uk

1) Does everyone charge the extra bandwidth consumed at 95%tile, or do many (as someone suggested to me) just forget about the extra 'as long as you dont take the mickey'.

Depends on the supplier and the level of automation - we do bill for overages, but we also work with clienst to ensure theire CDR's are appropriate, and regularly supress invoices for small amounts.

Quote:

Originally Posted by reactive-uk

Conversely is charging all customers their 95% peak (and assuming these peaks dont occur together) actaully a good profit source for the hosts?

Generally its how the upstreams do their billing, so thats whyit's billed onwars like that - it rarely works out an "earner" as 95%ile removes the peaks, which when combined often are enoughfor our 95%iles to be higher ...

we find for example that 7.45am Monday morning is our peak traffic point, which also coincides with most clienst peaks, but because there aren't 36 of them/month, it doesnt hit the clients bills, yet due to the "spread" of them across the client range, does mean we previoulsy had to have much higher CDR to cope (policy is NO overselling, so our CRD's exceed those of combined customer CDRs)

Quote:

Originally Posted by reactive-uk

2) On dedi servers where they offer 999999Mbytes per month trafic on a 100Mbit port, I'm assuming that the actual max speed achieved depends to a great extent to how much they have oversold and what their upstream looks like ie I might get 50kbit dial up at the extreme!!

No bandwidth bills ever farcehosts rate limit you to between 32Kb/s and 2Mb/s depending on eth price you pay, and it regularly scales down to getting sub 15kbs although you'll get a 100Mb/s NIC connection ...

Overselling and overcontention is rife with some suppliers.

Quote:

Originally Posted by reactive-uk

3) So to guarantee 100Mbit across my x (maybe 5) servers, I would need to buy that total requirement as a CDR and let my servers fight it out amongst themselves (or otherwise manage it?)

yes, how you do it depends on your traffic profiles and your switches, is all the 100Mb/s actually internet traffic or is some internal. woudl caching engines help etc ...

dazmanultra · 25th July 2008

Based on our experience, the usage on our average shared hosting servers tends to be somewhere around 200GB of data transfer to be equivalent to 1mbit 95th percentile.

markcastle · 25th July 2008

Like Rob we regularly don't bill for small overages, but we definitely do for anything over a certain threshold. Incredibly we didn't used to bother to bill for bandwidth overages, but we had clients that were really taking the pish - big time. Those were the ones that were up in arms when we started billing overages.
Re: 95th Percentile... we mostly bill using 95th but some clients need to be billed in GBytes, we actually have one contract where the client is allowed to change from GB to 95th once if they need to.
Most clients have no clue what 95th Percentile means so we describe it as you can burst to 100Mbps (or GigE) for 5% of the month and not be charged for it.. they seem to like that.

[inx]Olly · 25th July 2008

We have very few (few dozen) dedicated clients left now, since concentrating soley on gaming, but we do take the same approach. Overages are only shoved on for p1zz takers.

With regards to the port, it depends on the provider! If the provider attracts high bandwidth clients and you are sharing a 100mbit port, you are buggered.

You'd be surprised how many still sell 100mbit not just on a 100mbit switch, but on a 100mbit network. Nightmare!

If you are colocating / dedi-ing with a web host like Daz says above, you'll get real under contention.

We currently have gbit to all our individual racks and generally do about 30mbit to each on our main racks. Some will do a fraction of that. With some colo / dedi hosts you are looking at 10x that and during peak time you might see a slow down.

Best thing to do is ask your potential provider a few questions before hand.