Setting up a wired sub-LAN

By wolfram
Feb 22, 2010
  1. Hi everyone,

    Today I was asked to setup a small network for a classroom. I need to network 4 computers and share a single printer. They also need Internet access (this is where it gets tricky for me).

    I was thinking a simple switch would do the job (sharing the printer and networking the machines), but what about the Internet? A single UTP cable coming from another classroom brings the Internet here (this cable is connected to a 48-port switch, which is connected to a 2 wire modem/router provided by the ISP).

    So do you think I could just use that cable, connect it to the switch and configure it to share the Internet? I hope I explained this good enough :eek:

    Thanks =)
  2. jobeard

    jobeard TS Ambassador Posts: 9,149   +597

    let's try to get a map of what you have:
    isp --- modem/router---48port.switch-->classrooms
    and one of the 48 comes to you, right?

    you have ONE port on the switch, but need four systems to share it. That will require your
    modem/router to support more that 48 connections, ie the DHCP service it provides needs more that 48 addresses.

    The for-sure solution is to take
    this will isolate your classroom from the other 47 connections but still allow Internet connectivity.

    Attach your printer to ONE of your four systems and use Print/File Sharing for your class use. (the other classrooms will not see you at all.)
  3. wolfram

    wolfram TechSpot Paladin Topic Starter Posts: 1,967   +9

    Hey thanks for your response!

    The map you made is correct. Yes a wire coming from the 48 provides internet to the teacher's PC. That's where I want to place the switch/router, so the other machines can have Internet and normal networking. (turns out I'll probably need to connect 5 PC's)

    The modem/router is a 2wire 1070. Do you think that would have enough addresses? I'd think it would support at least 100, but I really don't know.

    Thanks for helping me to clear this mess out :) (I'm a newbie at networking lol)

    I made a quick drawing in word to explain what we have:
  4. jobeard

    jobeard TS Ambassador Posts: 9,149   +597

    Using the 8-port switch would allow
    all the students in your class to see every other system
    and all the systems in the school to see/access your classroom​

    The 48port switch in your drawing (normally) does not support DHCP service;
    it (DHCP) would have to come from the modem in front of it

    Place a NEW 4-port router ($49) of any make (suggest NOT wirless) between the 48port switch and your 8port ENH908;
    it will support the DHCP for your classroom only, have 3 user ports and the 4th to attach the ENH908
    AND isolate your class from all other classes and vise-a-versa

    You can cable the classroom systems anyway you like.

    Tip: if the ip address coming into your room is 10.x.y.*, then set your new router to
    have a router IP address of 10.x.y+10.1

    When you're ready for the install, we can complete the config ...

  5. wolfram

    wolfram TechSpot Paladin Topic Starter Posts: 1,967   +9

    Hi again,

    I'm aware the 48 port switch (which is in another classroom) does not support DHCP. I believe the 2wire 1070 modem/router provides DHCP support (I had one in the past and it did provide DHCP), that's why I was thinking it could simply assign an IP to these new machines.

    I'm trying to keep all this as cheap as possible, so do I really need a router? This would be so easy to setup if they had dedicated Internet service in their own classroom.........

    Thanks! =)
  6. jobeard

    jobeard TS Ambassador Posts: 9,149   +597

    you would need a router to isolate your class from the school per se and if that's not required,
    then the modem should be able to provide four more addresses :) just add the switch.
  7. wolfram

    wolfram TechSpot Paladin Topic Starter Posts: 1,967   +9

    Hey man thanks a lot for your help, I'm posting this from the new network =)

    Thank you a lot!
  8. jobeard

    jobeard TS Ambassador Posts: 9,149   +597

    Bravo -- well done :)
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