question about ISPs

Discussion in 'OT Technology' started by babygodzilla, Nov 3, 2004.

  1. babygodzilla

    babygodzilla I love rice

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    how does an ISP work? im wondering specifically about hardware. how does an ISP split bandwith between thousands of customers? they use switches, routers, or what? im sure they dont use my home Linksys router. what about wireless internet service?
     
  2. sleepy71

    sleepy71 Guest

    It's different for different ISP's, depending on their type of service (cable, DSL, dial-up). At the root of it all, you'll see a lot of the same gear at all places (routers, switches, fiber). I'm not sure about wireless (i.e. Clearwire).
     
  3. babygodzilla

    babygodzilla I love rice

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    can you give me specific details about those "same gear at all places"? like what kind of router they use? how much bandwith, how many users can that router accomodate? etc
     
  4. P07r0457

    P07r0457 New Member

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    bandwidth depends on the speeds they offer, and the # of users they offer it too.

    For example, a T1 can support 30 dialup users w/o overselling. It wouldn't be uncommon for a T1 to support several hundred dialup users -- because they're not all online at the same time. An ISP makes money by "overselling" their service, knowing that the worst-case scenario (everyone trying to max it out at the same time) is a statistical anomoly.

    However, a T1 would be unable to support even just 1 cable user's downstream needs. (although it could handle about 3 upstream users). A DS3, on the other hand, could easily handle 15-20 cable users w/o being oversold. It wouldn't be uncommon to support over 100 customers on that -- and I do mean *over*.

    As far as equipment, it varies greatly. Factors include the bandwidth needed (equipment for a T1 is quite different than for a fibre loop, or even a DS3) In generic terms, a "router" is required -- which one depends on what you have comming in.

    For dialup you then must have some modem racks and an authentication server. For all intents and purposes, a dialup connection is "uncapped". Meaning that they do little to nothing to limit your speeds. Speeds will be limited to the negotiated speed between your modem and the modem rack. So the rack may have a 100Mbps ethernet feed, and you can pull as much as you can get through your 53Kbps pipe.

    DSL requires a DSLAM which takes care of modem handshaking and usually authentication, as well. A DSLAM takes care of bandwidth management through the use of "caps". 768kbps down and 128kbps up is common. 1.5Mbps/256Kbps is also common. The DSLAM has several ports (16, for example) and each port can be turned on or off, and service settings can be set. The DSLAM will have an upstream feed -- some taking ethernet to a router, others taking a DS3 or similar connection directly. Each port of the DSLAM is connected to the local loop servicing a DSL user. The DSLAM receives data upstream in a very quick manner, but then throttles it at the port to the user's set speeds. Uncapping DSL requires access to the DSLAM, and the use of equipment supporting the desired speeds.

    Cable is probably the most complex of the networks. In it's simplest form, Cable requires a modem, a coax cable, and a CMTS. The CMTS takes care of negotiating with the cable modem. Bandwidth throttling is actually performed by the Cable Modem, and not by the CMTS. This is why you may have heard about "uncapping" cable modems. Unlike with DSL, "uncapping" does not require administrative access to any equipment located at the CO/POP. Even when a user has not paid their bill, the CMTS will likely negotiate with the modem. However, it will be sent a "disabled" config by the TFTP server. Part of the negotiation process is for the modem to grab it's SLA from a designated TFTP server. This config has various configuration variables, such as upstream and downstream caps -- both soft and hard. The network to the cable modem is extremely fast -- usually 38.4 or 45Mbps. It is then the job of the cable modem to throttle speeds to acheive an "average" matching the SLA.

    On a cost scale, Dialup is the cheapest. It requires only a modem and a computer with an internet connection. DSL is next, requiring a DSLAM, and access to local loops and an internet connection. Cable is the most expensive initial investment -- but probably has the highest reach, expansion, and profit potential.

    Are you looking at starting your own ISP?

    I do not recommend starting dialup -- it's a hastle and can be costly. Instead, find a "brand your own" dialup service. They charge you a low fee, such as $5 per line, and then you sell it under your own name to customers and make whatever you want -- so sell for $10 and get $5 each account. You then run the customer service, and the other party handles the physical sides of it. This is nice because many services offer nationwide access numbers -- a crucial feature if you want to compete, imo.

    It is possible to start a DSL service, but probably not a good idea to control the show. To do it all, you'd have to lease space in the telco's CO. Then you must worry about local loops, a DSLAM, upstream connection, etc, etc. Most telco's now do a similar "brand your own" service where you pay the telco a fee per-line. That is a reason so many "no-name" services have come online for DSL recently.

    Running your own cable system is almost entirely out of the question -- unless you know a small town without cable that you want to start your own full-serve cable provider. However, many cable companies will also support a "brand your own" service. Earthlink, for example, does not own any cable companies that I know of, yet through arangements with local providers, are able to provide "branded" services.

    I did not discuss wireless because they are largely non-standard. Although possible to setup a large WiFi network, most wireless providers do not use this... Each system is largely proprietary.
     
  5. babygodzilla

    babygodzilla I love rice

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    wow thanks so much! that was a very thorough explanation. yes my friends and i were talking about starting an ISP in a city where DSL/Cable runs at the speed of Dialup, its ridiculous. the thing is we were really looking into wireless internet (WiMax? 802.16?). Since the infrastructure of the city is horrible, fiber optics barely exist and to lay down new lines will not be cost-effective at all in terms of time and money (but i guess time == money :p ). i've been reading about wireless internet over a city, i think they're doing it in Philadelphia or something like that. i've also heard stories of remote villages where phone lines barely exist, if at all, but having wireless internet. i've setup simple wireless home networks, and while the process and equipment needed for an ISP is obviously a lot more complex, i thought that the underlying principles of a wireless network is basically the same.

    what do you think is the capital needed to start an ISP?
     
  6. P07r0457

    P07r0457 New Member

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    depends on too many factors for me to give you an estimate. Wireless has a very high initial investment. It will likely require specialized equipment at the client-side, as well.

    First thing is first -- what interest level does your customer base have? And at what price are they willing to pay?
     
  7. sleepy71

    sleepy71 Guest

    Look at www.clearwire.com. They recently opened here in Jacksonville. Seems like its a good alternative to "traditional" Hi-speed Internet.
     
  8. babygodzilla

    babygodzilla I love rice

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    hmmm we havent really thought that far yet. still thinkin on how to actually BE an ISP. but i can say im 90% sure that potential customers will be highly interested in wireless, FAST and RELIABLE broadband internet, and at a reasonable price. cuz im not joking broadband in this city runs at dialup speed. its probably fast in business areas, but in residentials, which makes up for more than half of total internet subscribers, it sux complete ass. like i said, hardly any fiber optics, if any at all, and the infrastructure is too tangled up and messy to be cost-effective in installing new fibers.
    this is an asian city where people are big on playing Counter Strike in internet cafes (paying hourly for LAN access). imagine if i could blanket the whole city in one wireless network! those gamers wouldnt be stuck in one cafe and in one LAN for hours. they'll be connected to the whole city (and the world) from anywhere they want and it'll be one huge playing field. and there are LOTS of gamers there, in the hundreds of thousands. just that part of the pie would be a nice customer base.

    you mentioned some specialized equipment at the client-side. wouldn't those just be wireless network cards?
     
  9. P07r0457

    P07r0457 New Member

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    no. A WiFi card gets about 100ft range when you account for walls and what not. So unless you wanna have a WiFi access point every 2-3 houses then it's not gonna work. You can use high-gain equipment at the access point side, but without an antenna capable of sending back, it's useless.

    Also, remember that data security is a big concern for a large public wifi network. And wep is NOT sufficient.
     
  10. babygodzilla

    babygodzilla I love rice

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    i was thinking more of WiMax than WiFi. how bout those?
     
  11. IAMwhitey

    IAMwhitey New Member

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    what city are you in? chances are that you might have fiber near you, but its not lit yet.
     
  12. babygodzilla

    babygodzilla I love rice

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    im not really IN it rite now but i grew up in jakarta, indonesia

    as far as ive heard from people that subscribe to DSL/Cable over there, they've all been complaining about how utterly slow the "broadband" is, and they all live in different parts of the city, which leads me to think of the scarcity of fiber. there are slums all around the city and the government is way corupt. i doubt they'd be cooperative of installing new fiber.
     

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