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Is it possible to have 2 modems on UPC connection

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  • 23-09-2008 1:40pm
    #1
    franman
    Registered Users Posts: 260 ✭✭


    Sick of trying to get any sort of decent speed over wireless so I was just wondering is it possible to connect 2 modems on a UPC connection? if I get a cablem modem off ebay could I have one modem upstairs and the other downstairs?


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    #2
    watty
    Registered Users Posts: 32,417 ✭✭✭✭watty


    Only UPC can provision the modem. Anything else (assuming you got it to work, which is doubtful) is theft of service.

    Run a cat5 cable to your second location or pay for a second UPC account (they will supply a modem). Much cheaper to run a Cat5e cable than buy a modem, which needs coax anyway.


    You can probably run about 200 modems off your UPC coax, but UPC needs to enable them via suitable paid for accounts.


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    #3
    Tazzle
    Hosted Moderators Posts: 2,559 ✭✭✭Tazzle


    You can hook a switch up to the cable modem if that's any help.


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    #4
    watty
    Registered Users Posts: 32,417 ✭✭✭✭watty


    No you can't. You need an ethernet Router as the modem only gives out one IP address.
    Argos calls them "cable routers". They are "just" routers with no built in ADSL modem (if it has a DSL phone line modem built in there is no ethernet WAN port and thus useless for Cable or Other Broadband not via phone line).


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    #5
    MunsterCycling
    Registered Users Posts: 4,864 ✭✭✭MunsterCycling


    Never knew you had a stutter there watty... :D

    watty wrote: »
    No you can't. You need an ethernet Router as the modem only gives out one IP address.
    Argos calls them "cable routers". They are "just" routers with no built in ADSL modem (if it has a DSL phone line modem built in there is no ethernet WAN port and thus useless for Cable or Other Broadband not via phone line).


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    #6
    Tazzle
    Hosted Moderators Posts: 2,559 ✭✭✭Tazzle


    watty wrote: »
    No you can't. You need an ethernet Router as the modem only gives out one IP address.
    Argos calls them "cable routers". They are "just" routers with no built in ADSL modem (if it has a DSL phone line modem built in there is no ethernet WAN port and thus useless for Cable or Other Broadband not via phone line).

    Yes, you can. I have a switch set up. Get your facts right buddy!


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    #7
    Cabaal
    Moderators, Technology & Internet Moderators, Regional South East Moderators Posts: 28,490 Mod ✭✭✭✭Cabaal


    cable modem only gives out one IP though, so using a ruter you connect it to the WAN port and then the router shares it out and gives its own IP's to all devices connectwed, a switch can't dop this so your stuck with that one IP your cable modem gives out.

    Perhaps your "switch" has its own DHCP server and is actually working like a router?


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    #8
    MunsterCycling
    Registered Users Posts: 4,864 ✭✭✭MunsterCycling


    Or he's running his own DHCP on another box... but if he was then he'd of known the answer to the switch - UPC connection question.

    MC


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    #9
    bk
    Moderators, Motoring & Transport Moderators, Technology & Internet Moderators Posts: 22,718 Mod ✭✭✭✭bk


    franman wrote: »
    Sick of trying to get any sort of decent speed over wireless so I was just wondering is it possible to connect 2 modems on a UPC connection? if I get a cablem modem off ebay could I have one modem upstairs and the other downstairs?

    Your best bet would be to run a cat5e cable from a broadband router connected to the cable modem.

    If you can't do this then an alternative would be a pair of Ethernet over power boxes which allow you to run your broaband connection from your electricity plugs.


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    #10
    paulm17781
    Closed Accounts Posts: 4,858 ✭✭✭paulm17781


    Some of the newer UPC modems (claim to) have a DHCP server. I've never been able to get it to work so I assumed it was disabled. A switch definitely won't work with some of them but perhaps Tazzle has a newer modem / switch with DHCP.


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    #11
    Kensington
    Closed Accounts Posts: 3,683 ✭✭✭Kensington


    UPC cable modem will give out a maximum of 3 public IP addresses - so you using a simple switch (not a router) you can connect up to 3 PCs.


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    #12
    watty
    Registered Users Posts: 32,417 ✭✭✭✭watty


    All cable modems use DHCP to give out an address. How many addresses depends on the cable operator. UPC may not do the same thing in all areas. There is no good reason to give 3 addresses and a good reason to do only 1.

    It's bad practice to connect a switch, better to use a router and then you have a decent firewall and can have MS server/client filesharing safely on the LAN.

    They are very cheap.


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    #13
    paulm17781
    Closed Accounts Posts: 4,858 ✭✭✭paulm17781


    Kensington wrote: »
    UPC cable modem will give out a maximum of 3 public IP addresses - so you using a simple switch (not a router) you can connect up to 3 PCs.

    3 public IPs? Are you sure or do you mean private?

    As Watty said, a router is still best practice.


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    #14
    Cabaal
    Moderators, Technology & Internet Moderators, Regional South East Moderators Posts: 28,490 Mod ✭✭✭✭Cabaal


    paulm17781 wrote: »
    3 public IPs? Are you sure or do you mean private?

    As Watty said, a router is still best practice.

    Indeed a router is best practice and it gives the user more control
    - wifi
    - QOS etc


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    #15
    MrVestek
    Registered Users Posts: 9,216 ✭✭✭MrVestek


    paulm17781 wrote: »
    3 public IPs? Are you sure or do you mean private?

    As Watty said, a router is still best practice.

    He's probably doing what alot of people who don't know alot about networking do, set up three public IPs when he's only been assigned one address. Therefore he'd be using the other two public IPs illegally.

    Unless of course he's just getting confused and he's using a *wired* router.


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    #16
    Kensington
    Closed Accounts Posts: 3,683 ✭✭✭Kensington


    paulm17781 wrote: »
    3 public IPs? Are you sure or do you mean private?
    Nope, it's three public IPs (ie. three 79.xxx.xxx.xxx numbers). If it were a router assigning addresses, then you would end up with something like 192.xxx.xxx.xxx on each PC. Connect more than three PCs and it will either not be assigned an IP, or it will knock the PC with the oldest lease off and assign that lease to the new PC being connected.

    On a note of legality, I recall it being mentioned in NTLs old T&C that a maximum of three computers may be connected to their broadband service. Of course, using a router you could connect many more and as far as they'd be able to tell, only one PC (the router MAC address) would be connected to your broadband.
    Achilles wrote:
    He's probably doing what alot of people who don't know alot about networking do, set up three public IPs when he's only been assigned one address. Therefore he'd be using the other two public IPs illegally.
    You're not able to manually assign (any) IPs manually, gotta let the cable modem assign them via DHCP.


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    #17
    paulm17781
    Closed Accounts Posts: 4,858 ✭✭✭paulm17781


    Kensington wrote: »
    Nope, it's three public IPs (ie. three 79.xxx.xxx.xxx numbers). If it were a router assigning addresses, then you would end up with something like 192.xxx.xxx.xxx on each PC. Connect more than three PCs and it will either not be assigned an IP, or it will knock the PC with the oldest lease off and assign that lease to the new PC being connected.

    I do recall that in the old T&C but it definitely didn't work on the old '200' modem, you needed a router for that.

    I'm surprised the give out 3 public IP addresses, it's rare to see that these days.


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    #18
    Kensington
    Closed Accounts Posts: 3,683 ✭✭✭Kensington


    paulm17781 wrote: »
    I do recall that in the old T&C but it definitely didn't work on the old '200' modem, you needed a router for that.

    I'm surprised the give out 3 public IP addresses, it's rare to see that these days.
    It is a little odd as to why they still do it alright, but I can confirm that their current Scientific Atlanta EPC2203 modem (the one with the combined PacketCable VoIP phone ports) certainly allows up to 3 different MAC addresses be assigned a seperate, public IP.


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    #19
    Tazzle
    Hosted Moderators Posts: 2,559 ✭✭✭Tazzle


    I'm using a switch to connect a router to the cable modem, but also to give me the option of directly connecting pcs. It's a convoluted work around to the fact the router you get off Chorus/UPC is a load of crap and sometimes I need a direct connection to the web that doesn't get overloaded. So yes you can obtain one or more public IPs if you wish, at least with Scientific-Atlanta's EPC2203 cable modem you can.


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