how many people can share a T-1?

[wedi42]

i'm thinking of starting a wireless ISP
i need to know how many people can can share a t-1 line and still get good bandwidth?
i'd like to give everyone approx 1 megabit speeds
is there a rule of thumb used to determine the number of people that can use this without a big slowdown?
(something like the 10:1 user to modem ratio in dial-up ISPs)
would it matter if i connected with comparable speed DSL?

 

[nightowl]

Well a T-1 is only 1.544Mbps. So if you want to offer 1Mbps, you are not going to get too far. Also, DSL is going to max out at around 1.5Mbps.

 

[spidey07]

I've run thousands of people on a T1.

Depends on what folks are doing to gauge the bandwidth required. Asking to give 1 Megabit is really pushing it, maybe 10 people max. Just one persone could easily blow your service level of 1 megabit.

 

[wedi42]

there must be a rule of thumb out there.
it doesn't really matter if its a T1 or a T3 or whatever
i just want do know how much bandwidth i need to give X number of residential users 1Mbps service
if i had 100 customers, they'll only be online 10% of the time or so MAX and even then they won't be using all the available bandwidth all the time

 

[spidey07]

I guess you could say the rule of thumb is "it depends"

Most circuit sizing is done by estimate with ample room to grow based on engineering rules. One rule could be "If any trunk averages 60% utilization for more than 15 minutes then upgrade capacity accordingly". A T1 could service hundreds of simple web/email users. Or it could service one or two teenie boppers who like to dowload news and FTP all day, every day. Sorry I can't be of much more help.

 

[ScottMac]

Well, I don't know if it'll help or not...but consider this:

Last time I checked (a year or so ago) the ENTIRE sub-continent of India (1 Billion + people, several hundered million or so with potential access) was getting Internet access through a TOTAL of SIX T1s, with the main portal being satellite-based (through VNSL -VSNL?-) which was fed by GlobalNet...something like that.

The bandwidth was so expensive (and slow), that it was easier for compaines to burn a CD, ZIP disk, or floppy and fly to someplace (like Malaysia or Austrailia) and upload the files from there.

You can put as many folks on as you want, if you're going to offer some sort of Service Level Agreement, stay to the conservative side. If it's gonna be cheap access, then load it up and offer a "You get What You Pay For" statement.

Sprint is providing pretty decent service via Wireless in the Chicago Metro area, decent price point, reasonably quick, available to folks that otherwise wouldn't have the infrastructure....latency is a bit high, I've heard, but the foks that have it are so happy to go fast, they don't care.


FWIW

Scott

 

[IaPuP]

Giving out ISP service with a "guaranteed" 1MBps service is going to be VERY EXPENSIVE: Read: about $500/ month per user.

Since you're probably using 802.11b for a transmission point, keep in mind that you only get an effective throughput of about 3.5 MBps and an indoor range of about 100 feet. I don't know who you plan to serve with this, but unless it's your immediate neighbors, or you plan to put a booster antenna on top of the building and only offer service line-of-sight, then you're not going to have much luck.

As for getting a T1. I till cost you... I would estimate roughly $2500 per month is pretty cheap for an SLA on a T1.

You could look into getting an HDSL/RADSL connection that COULD give you about 7MBps of bandwidth and that would only cost you around $900 / month but you would have to be within a stones-throw of your nearest DSLAM or it's not an option.


So you might be able to get 30 connections on an array of 5 or 6 Access Points. Assuming buying the points and wiring them, setting up at least two servers and a good router will cost about $10,000 and that you could provide pretty good service with a $900 line. That means you would have to charge $70 per connection per month in order to break even in the first 8 months.

If you want to try to coax people off their DSL lines by only charging $55 per month, your break-even point falls about 13 months into it and we're still completely neglecting mantinence costs and network upgrades. This is also assuming that you're willing to work for FREE!


So lets say you want $1000 per month for your time (about $5 per hour) Even if you charge $80 per connection, that pushes your break-even point out to about 24 months, at which point- people will start to be mighty unhappy with their 3.5MBps wireless speed. Of course, then you're looking at another 10,000 upgrade.


Now, I understand why it's hard to run a wireless ISP- wires are cheap. Air, aparently, is not.

Eric

 

[IaPuP]

Just a few more comments.

I'm really not trying to be harsh- I'm just giving you a dose of reality.


Your asking for a rule of thumb. I can tell you this much:
When talking about small numbers of samples, statistics go to hell. Statistical averages only work for large sample sizes. If you asked how many users could average 1MBps on a connection like an OC-3 (155Mbps) then we could give you a reasonable answer. I think 10:1 or 8:1 might be a reasonable guess, so you could serve 1240-1550 users or so. On a T1 or a T3, we're talking in terms of one or two, not dozens.

To answer your question, How many users can I accomidate at 1MBps on a T1 line? The answer is ONE. If you can't make him sign a contract that he won't be downloading all day long and will leave when you tell him to, then you can't offer 2Mbps on a 1.55Mbps line. Even if you can make him leave at certain times of day, you can only offer reliable bandwidth to TWO people. Perhaps one in the morning and one in the afternoon? =-)

If you're thinking of setting up a wide-scale wireless network which can do hundreds of users, your concerns are probably more with wiring the wireless equipment into remote locations (since 2.4GHz technology can only go through 2 walls or so before it simply doesn't work too well).

If you just want to serve your apartment building, you could probably do that, but don't expect it to be a cheaper option than DSL, especially if you try to guarantee 1Mbps. I imagine (looking at my example above) that you would want to charge about $90 - $100 per connection per month to make it worth your while. Will people pay that?



Eric

 

[wedi42]

my only compition is satelite or dialup (33.6 not even 56k)
so i only have to be better then 500Kbps for $90/mo
i was hoping to offer 1Mbps(+lower latency) for $80-90/mo
i have an opprotunity to serve a unique neighborhood with 200 homes of very rich people all with a view of a single watertower
i think 50-75 homes would sign up
i wouldn't guarantee 1Mbps, just say 'download speeds up to 1Mbps'
i was hoping to figure out what sort of connnection to get so i can do more planning

 

[blstriker]

50-70 homes should be no problem. The main problem will be the antenae placement and power. Antenae are very expensive and you have to choose what type, omni, sector, yagi, parabolic, etc. Good luck!

 

[wedi42]

thanks for the opinions people

does anyone here run a wireless ISP, i'd love to chat with them?

or does anyone know of a better forum to ask this question?

thanks

 

[Jwyatt]

I was listening to a computer talk show this morning. They had the local president of our Road Runner high speed stuff.

He said they generally monitor the networks and have a plan called 70-30. Where if 70% of the people use up to 30% of the capacity its time to upgrade that service area.

Not sure if this helps you any though. Good luck

 

[rawko]

Let's say you have 50 customers at 90 a month, for a total of $4500. You could get a t1 or 2(don't forget equipment costs. thats why i figure 1 or 2), but not much else before you start to loose money. Let's also say that 10% of the people will be on at a time and actually browsing or downloading so that's 5 people. If you had 2 t1's they would be pretty happy or even 1, they might be happy if they are coming from a modem. On your side of things, you could get away with a relatively cheap (sub $1000) server, and 2500 series cisco router for less than a grand as well or just let your isp supply it. Just don't gaurantee anything unless your customers want to pay more.

 

[Nutz]

This is just a hypothetical but its interesting to say the least.

Income:
75 users at $90/month =$6750

Expenses:
T1 $1000/month plus $2000 setup fee
Router ~$1000
Server ~$1000

Wireless hardware per home (one time purchase) $250 @75 homes=$18750. This averages to $1562.50/month if payed over one year.

Acess Point on water tower ~$650
Installation fee $2000 and then another $250/month for the mounting lease
CPE (wireless transceiver) ~$250

So just to crunch the numbers here you go:

Startup Cost: $6650

Monthly costs: $1250 +554.17+250=2054.16 This doesn't include electricity, racks, cabling, etc.

So $6750-2054.16=4696 Not too shabby, but there are alot of costs not included in this little guesstimate.

 

[rawko]

you can probably pass along the customer hardware cost on to the customer