How many 384kbps users can I serve on a T1 1.5mbps dsl line?

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Request for Question Clarification by alienintelligence-ga on 13 Oct 2002 01:57 PDT

Hi afreestyle,

Is this a hypothetical question or an actual
one?

The reason I ask is, most DSL providers will
have in their contract that you cannot "resell"
or otherwise redistribute your connection to
others.

You also just state DSL... would that be ADSL,
HDSL or SDSL? Big difference there.

I'm gonna say 3... if you are guaranteeing
384k continuous.


-AI

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Clarification of Question by afreestyle-ga on 13 Oct 2002 13:10 PDT

It is ADSL. The DSL provider allows servers and wireless 802.11b
sharing as long as you don't use up to much bandwidth. I was thinking
about sharing a T1 line with my neighbors.

I have a cable modem that I use regularly that doesn't allow servers.
So I was going to get the T1 line for my server and share some
802.11b.

I read an article some where that not to many people actually use more
than 384kbps. So I was trying to get an idea of how many neighbors I
could share with.

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Request for Question Clarification by alienintelligence-ga on 19 Oct 2002 04:56 PDT

Hi afreestyle...

Just to clarify, you are tossing
around the terms T1 and DSL quite
interchangably here. You are aware
there is a difference, right? Are
you referring to the DSL as being
"T1 Speed"?

You stated that it's ADSL. That means
asynchronous or more bandwidth down
than up. Typically the ADSL lines are
capped at 128k-384k on the upload. 
Are you taking the users' requirements
for uploads into consideration also?

I still say 3 users (not including your
usage).

-AI

That depends on what kind of traffic your users are using.

If they are all doing streaming video, it's going to be a low number
of users.

If they are all only doing text browsing and email, then you could
probably have hundreds.

But, for a practical amount, just figure how many based on each
getting about 64k, or about 6 users. Keeping in mind that more than
likely they all aren't
going to be hogging bandwidth at the same time.

Also, it would be wise to invest in some sort of firewall with traffic
shaping capabilities. My network is connected via 1.5Mb DSL. I have a
linux based firewall that does NAT routing for the lan and also
traffic shaping. It is setup in such a way that no one application can
hog all of the bandwidth available.

yeah most open source OSes have software traffic shapers. There're
also hardware shapers built in to some NAT/Firewall hardware.

Well if it is just the math of the thing then 384k is good for 4
connections. Normally at an ISP they have assumptions about how many
of their clients will be connected at once so they oversell. For
instance for dial-up service an ISP might only scale so that 1 in 10
customers might be connected at any given time. This kind of math
works on a large scale well, but terribly on a small scale. You can
probably only safely sell to 5 people unless you don't promise 384k to
them. If you say "usually" 384 kbps then you could probably go to 6
people. Keep in mind if all 6 people are on then each gets about 256
Kbps. Still a nice speed, but not the 384 they might have been
expecting.