How to determine DS3/T3 bandwidth needs? And a DNS question.

My boss is wanting to see how much it would cost to host our server
ourselves vs. using Rackspace. So I'm trying to price DS3/T3 options,
and I'm running into a problem. One that's probably rediculously stupid
and simple to experienced network gurus. =)

All I know from Rackspace is that we currently use on average 110GB of
traffic a month, and on some days as much as 10GB (both up and down.)
I'm looking at DS3/T3 providors, and they measure bandwidth usage in
what looks like -at-the-moment measurements. Like 9Mbps.

How can I determine what my DS3 needs are based on what our currently
monthly average is?

(Ready to be flamed with "that's so obvious you ignoramus!" *grin*)

The other question I have is the need to have a seperate DNS server.
Our server hosts many Web sites. Obviously, Rackspace handles the DNS.
Now, we wouldn't want to have our Apache server to ALSO run the Bind,
do we? Or can we? When I did tech support for an ISP once, I know we
had a seperate server that only ran Bind while a seperate server ran
Apache.
So, if we decided to host our server ourself, we'd need a box for both
the Web and DNS? Or not?

Thanks for any feedback!!
Liam

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...

> All I know from Rackspace is that we currently use on average 110GB of
> traffic a month, and on some days as much as 10GB (both up and down.)
> I'm looking at DS3/T3 providors, and they measure bandwidth usage in
> what looks like -at-the-moment measurements. Like 9Mbps.
>
> How can I determine what my DS3 needs are based on what our currently
> monthly average is?

You can't, you can only really guess. Different providers have different
ways of computing the usage on which they bill you. You have to model your
traffic and see what number you get out for the particular billing scheme
they use.

For example, suppose a provider has a billing scheme like "$X for every
Mbps, measured as 95% usage in highest direction". One way to guess what
you'd get by this measure is to write a program to convert your server logs
into bytes transferred for every five minute interval. Sort the intervals by
number of bytes. Divide the number of entries by 20, and take the entry at
that position. So if you had 100 entries, you'd take the fifth highest
entry.

Say that was 117 megabytes. 117 megabytes in 5 minutes is about (times
8, divide by 5, divide by 60) 3.2Mbps. Add a bit for overhead.

> The other question I have is the need to have a seperate DNS server.
> Our server hosts many Web sites. Obviously, Rackspace handles the DNS.
> Now, we wouldn't want to have our Apache server to ALSO run the Bind,
> do we? Or can we? When I did tech support for an ISP once, I know we
> had a seperate server that only ran Bind while a seperate server ran
> Apache.
> So, if we decided to host our server ourself, we'd need a box for both
> the Web and DNS? Or not?

I can't think of any reason you'd need a separate box just for DNS. But
you would probably want to find a few people willing to run secondary DNS
for you. Probably whoever you get a DS3/T3 from would offer you this.

I caution you that you should factor reliability, service, and
connectivity into your equation. Presumably a colocation provider will have
much better connectivity than a single DS3 to a single provider. You should
also take into account the improved ability to handle burst load and easier
growth. (You have to decide how important these factors are in your
application, of course.)

DS

David Schwartz wrote:
> <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) oups.com...
>
[..]
> > How can I determine what my DS3 needs are based on what our currently
> > monthly average is?
[..]
> For example, suppose a provider has a billing scheme like "$X for every
> Mbps, measured as 95% usage in highest direction". One way to guess what
> you'd get by this measure is to write a program to convert your server logs
> into bytes transferred for every five minute interval. Sort the intervals by
> number of bytes. Divide the number of entries by 20, and take the entry at
> that position. So if you had 100 entries, you'd take the fifth highest
> entry.

Huh. So, let's say, before I investigate 5 minutes of traffic and go
with the numbers I have at the moment, our average day is 5GB of
traffic, for the day.
5000MB * 8 = 40000.
40000 / 86400 (seconds in a day) = 0.46Mbps ?

So, I only need to look at 1Mbps services? That's like a full T1 isn't
it?
I can't imagine that's all we'd need. I mean, here at the office we
have a 512Kbps connection and 1 FTP transfer can bring the Internet
access to a halt for everyone else.
I can't imagine what 2 or 3 FTP's and a SCP transfer and dozens of HTTP
gets at any given moment would do!

> [..]
> I caution you that you should factor reliability, service, and
> connectivity into your equation. Presumably a colocation provider will have
> much better connectivity than a single DS3 to a single provider. You should
> also take into account the improved ability to handle burst load and easier
> growth. (You have to decide how important these factors are in your
> application, of course.)

You're absolutely right!
And that's certainly something we'll be considering quite
significantly.
Thanks for the reply!!
Liam

(E-Mail Removed) wrote:

> How can I determine what my DS3 needs are based on what our currently
> monthly average is?

You need more than your average. You also need to know your peak load. If
all your traffic comes in huge peaks, you'll need more bandwidth than if
it's more or less constant.

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) ups.com...

>> For example, suppose a provider has a billing scheme like "$X for
>> every
>> Mbps, measured as 95% usage in highest direction". One way to guess what
>> you'd get by this measure is to write a program to convert your server
>> logs
>> into bytes transferred for every five minute interval. Sort the intervals
>> by
>> number of bytes. Divide the number of entries by 20, and take the entry
>> at
>> that position. So if you had 100 entries, you'd take the fifth highest
>> entry.

> Huh. So, let's say, before I investigate 5 minutes of traffic and go
> with the numbers I have at the moment, our average day is 5GB of
> traffic, for the day.
> 5000MB * 8 = 40000.
> 40000 / 86400 (seconds in a day) = 0.46Mbps ?

No, that's useless. Use your server logs.

> So, I only need to look at 1Mbps services? That's like a full T1 isn't
> it?
> I can't imagine that's all we'd need. I mean, here at the office we
> have a 512Kbps connection and 1 FTP transfer can bring the Internet
> access to a halt for everyone else.
> I can't imagine what 2 or 3 FTP's and a SCP transfer and dozens of HTTP
> gets at any given moment would do!

No, no no. You have to design for *peak* usage. Average usage is a myth.

DS