Basic structural overview -- what is what -- modem, router

Hi there,
please help me into this world and confirm or correct my statements as soon as you find an mistake:

  1. OpenWRT supports devices including and excluding a DSL-modem.
  2. If you want to use a device without a modem (e.g. Raspberry), you need a modem device as well, ending up with two devices.
  3. In this case, OpenWRT acts as a router only.
  4. You need a modem that fits to your DSL, to be more precise: a modem that converts your V/A-DSL version 1/2/2+ to ethernet.
    4a) The router interacts just as a bridge between two ethernet ports.
    4b) A Raspi as a router would then just "translate" (interact) beteween two networks (ethernet ports).
    4c) To use a modem and a raspi (with only one ethernet-port), you need an ethernet device (attached on Raspi via usb) in addition.
  5. This "modem device" can be a router with a modem, but that would acutally be too much. A modem alone is just fine.
    5a) A modem alone usually needs less power than a router including a modem.
    5b) It you have a slow DSL (e.g. 16 kbps), almost any cheap ebay modem will do.
    5c) Go to wikipedia/DSL and find yout which DSL you have and then lookup a matching modem.
  6. This OpenWRT-device is to pick depends on your needs.
  7. With a Raspi, you can have a graphical interface on your OpenWRT. You can connect with VNC from your windows/mac PCs to it (to manage nightly downloads via DL-manager/firefox/jDown2 e.g.)
  8. Nr. 7 is half-way easy to set up (and no topic for here).
  9. To replace a regular router (e.g. Fritzbox), you need WLAN AP and an ethernet switch/ethernet hub as well.
  10. Conlusion:
    10a) Replacing your regular router with a Raspi, you end up with three devices (plus a usb/ethernet-device).
    10b) Telefony (in terms of DECT) does not work at all with Openwrt, unless your "modem" offers this feature.

Maybe one point answers another point as well, but I just tried to precise to make it easy to find mistakes.

Thank you very much! :slight_smile:

Maybe but I've never heard of anyone doing that. Mostly the GUI people use is LuCI, which is a web based app running on the router

  1. openwrt supports modems based on some chipsets
  2. depends on your internet connection, dosn't it ? not all require modems, but yes
  3. possibly, depends on how you chose to configure the modem

4a. the router, acts as a router, what's your definition of bridge ?
4b. yes, it'd route ...
4c. not really, it's configurable in other ways too, but an additional port makes life easier

5a. probably, but not necessarily
5b. if it supports the DSL standard your ISP is providing, and you don't care if openwrt can be installed
5c. find out which modems your ISP is/have been offering, and buy a used one, or one that's been used with your ISP

  1. no, on ISPs requirements (assuming you're still talking about the modem)
  2. There's a web interface, and you can hook up a monitor to if for the CLI, is using a RPi
  3. get a combined modem router, don't install openwrt on the RPi, or run some other Linux dist on the RPI, they're all cable of acting as routers.
  4. Depends on if you need wireless or not, routers can be made APs too, and are cheaper
    switch isn't really needed but it depends on how many wired ports you need.
  5. depends on what kind of telephony we're talking about, analog perhaps not, voIP is supported via asterisk.
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1-- most DSL modem chipsets are not supported. Unless your device is in the table of the supported "router with ADSL modem", the modem is not supported.

7-- OpenWrt does not provide a GUI, so if you connect the HDMI port you will only see text console. Afaik VNC is also not provided by OpenWrt since there is no GUI, you can do remote text console with SSH.
Most applications provided by OpenWrt either have a web interface (like a consumer router), console-only interface or remote-control interface (where you need an app on your PC or smartphone to control the application on the OpenWrt device)

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You may also find it useful to review the terminology here New Users: Basic Terminology Router, Access Point, Switch, gateway etc