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Three Macs and a Cable - Mac Networking

I apologize that this is inherently a somewhat complex question, so please bear with me. I'll try to describe it as quickly and simply as I can. Including a employer-owned PowerBook, I have three Macs that I hook up to the internet via Time-Warner cable (RoadRunner). Generally speaking, they each have a separate connection to an Ethernet hub/router, and the cable modem is another of the connection to that router, as is my printer. I need the network just to communcate between the Macs and with the printer, and since the cable modem hooks up through Ethernet, that's how it ...

  1. #1

    Default Three Macs and a Cable

    I apologize that this is inherently a somewhat complex question, so please
    bear with me. I'll try to describe it as quickly and simply as I can.

    Including a employer-owned PowerBook, I have three Macs that I hook up to
    the internet via Time-Warner cable (RoadRunner). Generally speaking, they
    each have a separate connection to an Ethernet hub/router, and the cable
    modem is another of the connection to that router, as is my printer. I
    need the network just to communcate between the Macs and with the printer,
    and since the cable modem hooks up through Ethernet, that's how it has to
    hook in. The Macs see the cable modem through DHCP.

    I have noticed that switching between computers is a bit of a pain when it
    comes to talking to the cable modem. It sure would be nice if any of the
    computers on the network could access the internet through the cable modem
    at any time, but it doesn't work that way. At most only one computer can
    have a successful internet connection at a time, and often having two or
    more computers on at the same time causes all of them to lose the internet
    connection.

    What I can do - although it's a bit of a pain - is to transition between
    two Macs by:

    * Making sure that all Macs are asleep or off,
    * Cycling power on the cable modem, then
    * Unsleeping the Mac that I want to work on the internet with.

    Even that doesn't work reliably though. The cases in which it doesn't work
    seem to be related to how much or how little time elapses between when I
    cycle power on the modem and when I unsleep the new Mac.

    I'm guessing that what's going on is that the cable modem performs an
    IP-layer bridge between Ethernet and whatever protocol is going on over the
    cable. Since TCP rides atop IP, and is a connection-oriented protocol, I
    can only have one Mac connected at a time. That is, I have to break the
    TCP connection to get the protocol to reset itself. The timing problems
    then relate to time-out periods in TCP protocol.

    Two of the three Macs are running MacOS 9, and the other usually runs OS
    X. The cable modem, owned by Time-Warner, is apparently made by 3Com
    called "Home Connect." One of my friends hooks up two or three PCs through
    a wireless Ethernet connection to a different type of cable modem and has
    no problems.

    Waddaya folks think? Is there some better way to make the connection to
    the modem through the network, preferably one such that all three Macs can
    be powered up at the same time and can the internet freely? Or perhaps
    some more realistic way to reset the protocol other than cycling power on
    the cable modem?

    Thanks for the ideas!


    Gary Guest

  2. #2

    Default Re: Three Macs and a Cable

    In article <rr.com>,
    Gary Morrison <rr.com> wrote:
     

    Yes. Replace the hub with a 4-port DSL/Cable router. You'll get the
    added benefit of a firewall in the router.

    --
    You are what you eat, therefore, I'm a vegetable! Cows and chickens
    and Pop Tarts are too.
    Howard Guest

  3. #3

    Default Re: Three Macs and a Cable

    Gary Morrison <rr.com> wrote: 

    The easiest way is a router (hardware or software)

    hth

    Anton
    Anton Guest

  4. #4

    Default Re: Three Macs and a Cable

    In article <rr.com>, rr.com wrote:
     

    If your "Ethernet hub/router" is really a router, you have it connected to
    the cable modem incorrectly. There should be a distinct "WAN" or "uplink"
    connection, separate from the bank of "hub" connections.

    If it isn't really a router, your solution is to get something that *is*
    really a router. The *router* will provide DHCP services to the Macs.
    The cable modem will see only the router connected to it.
    Alan Guest

  5. #5

    Default Re: Three Macs and a Cable

    On 2003-10-14, Gary Morrison <rr.com> wrote: 

    Is the modem on the uplink side of the router? If it isn't, that's
    where you want it. If it is, you've either misconfigured the router
    or it's not the right sort to be using in this context in the first
    place.


     

    It's a bridge, but none of this is relevant to your question.

    The router should get its address through the modem, via dhcp (router
    as dhcp client); the rest of the devices in your lan should get their
    addresses from the router (router as dhcp server); and the router
    should provide NAT for the lan devices that need to connect to the
    internet. If your router can't do this, get a more modern one that
    can - they're very cheap these days. At the same time you can get
    one with a switch instead of a hub.

    The only complicating factor is if your cable system will only give
    an address to registered device. If so you either need to tell them
    about the router (ie give them its uplink ethernet address) or you
    need the router to masquerade as one of the devices that's already
    registered. All modern router/switches I've ever seen can handle
    masquerading. If yours can't, that's another reason to replace it.







    Hugh Guest

  6. #6

    Default Re: Three Macs and a Cable

    Gary Morrison <rr.com> wrote:

     

    Sounds to me like you need a router.
    +++++++++++++++++++++++++
    H.B. Elkins -- Beattyville, KY
    http://www.millenniumhwy.net hbelkins(at)mis.net

    "There's no doubt he's the best race driver in the world."
    --Dale Jarrett, on the late Dale Earnhardt

    Go Big Blue (Kentucky Wildcats)! Go #15 (Michael Waltrip, NAPA Chevy)!

    Vote Ernie Fletcher for Governor of Kentucky! http://www.fletcher2003.com

    To reply, just remove the restrictorplates...
    ++++++++++++++++++++++++++
    H.B. Guest

  7. #7

    Default Re: Three Macs and a Cable

    In article <rr.com>,
    Gary Morrison <rr.com> wrote:
     

    I think you're not understanding how the router works.

    First, each Mac should plug into one of the LOCAL ports on the router.
    The Cable modem should plug into the WAN (wide-area network) port of the
    router. That's how the router knows which signal to route to the local
    ports.

    DHCP is nothing more than a way of assigning an IP address to each Mac.
    Once all the Macs are turned on and have obtained their IP address from
    the DHCP server, it would then make no difference if the DHCP server
    disappeared. It has no function other than to assign an IP address.
    It's not involved in any subsequent network activity.

    I didn't read the rest of your sitution. But if what I wrote doesn't
    make sense to you, then your router's set up wrong.
    fishfry Guest

  8. #8

    Default Re: Three Macs and a Cable

    In article <rr.com>,
    Gary Morrison <rr.com> wrote:
     
    [snip]

    You didn't say what brand or model of hub/router you have. Are you sure
    it's a router? Judging by your problems, I suspect it's just a hub;
    either that, or your cable modem is plugged into the wrong port.

    If all of your hub's ethernet sockets just have numbers or "uplink" next
    to them, then it's just a hub, not a router. I suggesr you go out and
    buy something that actually says "router", "gateway", or "firewall" on
    the box.

    If there's one ethernet port that's labelled differently (usually it's
    "WAN"), then it's probably a router, and that's the socket your cable
    modem should be plugged into.
    Wayne Guest

  9. #9

    Default Re: Three Macs and a Cable

    > Is the modem on the uplink side of the router? If it isn't, that's 

    Tell me what you mean by the uplink side? The Ethernet hub has eight ports
    that, best I'm aware are equivalent in nature. Truthfully, I'm not sure whether
    its truly a router or just a hub. It's a NetGear DS108. I'll have to look it
    up.
     

    OK, so then I believe what you're suggesting that my Ethernet router itself,
    rather than any of the computers, would be what connects via DHCP to
    Time-Warner. The router would then have a different IP address for each of the
    computers and would bridge IP-layer between them.
     

    I can't recall either way, but I'm sure I can check.

    Thanks for the ideas!


    Gary Guest

  10. #10

    Default Re: Three Macs and a Cable

    On Tue, 14 Oct 2003 17:10:23 GMT,
    Gary Morrison (rr.com) wrote:
     

    It's a dual-speed hub, not a router.
    <http://www.netgear.com/products/prod_details.asp?prodID=69>

    Beverly
    --
    Bev A. Kupf
    "The lyfe so short, the craft so long to lerne" -- Chaucer
    Sus - Division One Champions 2003!
    Bev Guest

  11. #11

    Default Re: Three Macs and a Cable

    > DHCP is nothing more than a way of assigning an IP address to each Mac.

    But can the DHCP assign more than one IP address per physical connection (over
    the cable I mean)?

    Your description of the router strikes me as a pretty strong sign that what I
    have is merely a hub rather than a true router.


    Gary Guest

  12. #12

    Default Re: Three Macs and a Cable

    > You didn't say what brand or model of hub/router you have. Are you sure 

    That would not surprise me; I don't know for sure either way, but it seems
    likely that it's just a hub.


    Gary Guest

  13. #13

    Default Re: Three Macs and a Cable

    Gary Morrison wrote:
     

    (Well, to be more precise, DHCP would assign the router an IP address for
    communicating IP with Time-Warner.)


    Gary Guest

  14. #14

    Default Re: Three Macs and a Cable

    > It's a dual-speed hub, not a router. 

    Yip, that explains a lot alright.

    Thanks for the thoughts!



    Gary Guest

  15. #15

    Default Re: Three Macs and a Cable

    Gary Morrison wrote: 
    >
    > Tell me what you mean by the uplink side? The Ethernet hub has eight
    > ports that, best I'm aware are equivalent in nature. Truthfully, I'm
    > not sure whether its truly a router or just a hub. It's a NetGear
    > DS108. I'll have to look it up.
    >[/ref]

    A quick look at NetGear's web site shows that the DS108 is an
    8 PORT 10/100 Mbps Dual Speed Hub

    So the long and short of it is that to do what you want, you need to get
    a DSL/Cable router + 4 port switch. Then plug the cable modem into the
    WAN (Wide
    Area Network) port and the computers into the 10/100 switch ports.

    They are available at lots of places. They usually cost $50 - $100.

    Good luck.
    - David
    David Guest

  16. #16

    Default Re: Three Macs and a Cable

    On 2003-10-14, Gary Morrison <rr.com> wrote: 
    >
    > Tell me what you mean by the uplink side? The Ethernet hub has eight ports
    > that, best I'm aware are equivalent in nature.[/ref]

    A router, well, routes, between two or more networks. If it routes
    between two networks, it needs two ethernet cards (or chipsets or
    whatever) with least one port per card. It can also include an
    internal switch or hub, which would allow several ports to share a
    single ethernet connection.

    The typical router-switch box that many of us are using has a single
    port for one network (to connect to the internet) and 4-6 ports in an
    internal switch for the other (the lan). The internet port is the
    uplink. This is what's connected to the modem. The computers in the
    lan would then connect to the built-in switch's ports.


     

    The DS108 is a hub. One of its ports can be used as an uplink, but by
    itself that won't be sufficient for your needs, since this box doesn't
    route.


    You need a router. You can buy one with a switch built in and connect
    it as described earlier. You wouldn't need your hub in this
    configuration, unless you have more computers to connect than your
    new router-switch supports.

    Or you can you buy a simple router with one downlink port. In this
    case, connect the router's uplink port to the cable modem, as above,
    and the router's one downlink port to the DS108's uplink port. The
    rest of the devices connect to the DS108's other ports, as you're
    doing now. In other words your hub takes the place of the built-in
    switch.


     

    Correct.

     

    Typically the router would provide addresses for the downlink hosts,
    via dhcp.

     

    It would route IP packets.



    Hugh Guest

  17. #17

    Default Re: Three Macs and a Cable

    On 2003-10-14, Gary Morrison <rr.com> wrote: 
    >
    > But can the DHCP assign more than one IP address per physical[/ref]
    connection (over the cable I mean)?


    You won't be doing that. As far as the cable connection is concerned,
    you're being assigned a single address, which will be used by the
    router's uplink ethernet (when you buy your router, that is). This is
    a public internet address, accessible from anywhere.

    The lan hosts on the downlink side of the router each have their own
    connection, either through your hub or through a switch built in to
    the router. Each gets an address from via dhcp from the router (you
    can also used fixed addresses here, but we'll leave that option aside
    for now). The cable provider knows nothing about these: they're
    private addresses, inacessible except on the lan. The router takes
    care of the necessary address translations to give each host access to
    the full internet.





    Hugh Guest

  18. #18

    Default Re: Three Macs and a Cable

    In article <rr.com>, rr.com wrote:
     
    ^^^^^^^^^^^^^^^^^^^

    A hub and a router are two different things entirely. (though there
    are many devices that combine a router & hub or router & switch in
    the same box)

    Do you actually _have_ a router?

    Your description sounds more like you just have a hub.

    What brand and model # of router do you have?

    You do have the cable modem plugged into the WAN port, while
    the Macs are plugged into the LAN ports, right?

    Most routers will work pretty much "out of the box" assuming that:

    1) your cable provider does not require a PPPoE login or similar
    and
    2) your Macs are configured for DHCP

    If (1) is not true, then one usually just needs to point your web
    browser at the router's default address (usually 192.168.1.1,
    192.168.0.1, or 10.0.0.1) and set the login info.

    Assuming that you don't have a router, I would suggest that you get
    one with at least nominal Mac support (including basic Mac setup
    instructions). Or search groups.google.com for the router model
    and the word "Mac"...

    The other option is to get additional IP address from the cable
    provider, but this usually costs $$$ and a router will provide
    you with basic firewall protection.

    --
    Jim Glidewell
    My opinions only
    Jim Guest

  19. #19

    Default Re: Three Macs and a Cable

    In article <rr.com>, Gary Morrison
    <rr.com> wrote:
     

    How about this http://www.threemacs.com/
    Whytoi Guest

  20. #20

    Default Re: Three Macs and a Cable

    Thanks, everybody, for pointing out that there exist special-purpose routers
    specifically for the purpose of connecting multiple computers to a cable modem
    (and to each other of course).


    Gary Guest

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