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ethernet networking problem

Discussion in 'Misc Electronics' started by [email protected], Jun 30, 2005.

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  1. Guest

    good day!!!

    when i test my newly installed lan, i have a problem setting up its
    connections.I thought i can view all the stations or they will
    recognize each other. but when i open network neighborhood, what
    happened was there were groups of computer that recognized each others.
    say S-1, S-2, S-3,S-5. The other groups of computer recognized
    themselves. ex. S-4,S-6,S7.They are all connected to a single ethernet
    hub but why is it that they seemed to group into 2?
    We have 3 hubs here interconnected with the 3rd hub connected to a
    router (connected to a DSL line).When i try typing IPCONFIG at the
    command prompt, the first group of computers has no default gate way in
    them so it did'nt recognize other computers connected to other hubs.
    The second group of computers has a DEFAULT GATEWAY IN IT so it
    recognizes other computers connected to other hubs including the hub
    which is connected to the DSL line.
    Any help would be gladly apprciated. thank you
  2. Just to clearify some terms:
    IP: The adress of the host. Can be anything, but should be either a
    address range you own, or one of the private ( or
    Netmask: Netmask is included above. Think as the netmask as a filter.
    A ip is a 32 bit address, so is the netmask, so a mask of
    filters out all, but the last bit. If the address your box is trying to
    reach for is outside the last part, it will go to the gateway. So the
    gateway is ONLY applied whenever you're trying to reach for something
    outside the scope of the netmask.
    To help, it'd be usefull if you said what IP range you used, and your
    Normally, you'll only ask for GW whenever you want to pass on to the
    internet. Typycailly, the GW is the DSL modem.

    Btw, I hope you didnt buy new hubs...
  3. Guest


    it's ip addr range is

    yesterday i did'nt open the dsl only the local are network. but today
    when i open the router and dsl modem, the other station immediately got
    default gateway in them and automatically connected to the internet.
    They all recognize each other now when viewed in the network
    neighborhood. i don't know tommorrow. what might be the reason?
    you know, i spent my day testing the utp cable betwen hubs and station
    using my tester and their is always continuity. no problem on cable.
    But it displays only itself on the network neighborhood. other
    stations are not displayed. therefore, it is not also recognized by
    other stations.What could be the solution to this problem.

    by the way, i am a newbie. a first timer in managing a simple
    networking system.- sorry bout my questions but i appreciate greatly
    any ideas that come coz it helps me improved. thank you so much!!!
  4. John

    John Guest

    -- very simplified explanation --
    When PC's with a network card are powered up, they try to get an IP
    address from the network. Failing that, newer operating systems
    provide a default IP address, such as or (or
    some other default that's set by the user or an admin). It's possible
    that some of your PC's are in one block of addresses (169.254.3.x) and
    some in another (169.254.1.x). The PC's in a given network block will
    see the other PC's in that block, but not the PC's in other address

    When the PC's are connected to the router, they all get an IP address
    assigned by the DHCP server in the router. All the addresses will be
    in the same block, so all the PC's will see each other.

    (I also speak X.25)
  5. Guest

    i see. thanks. my next questions are, even if they are all connected to
    the same hub, it can happen that they will be in a different blocks of
    addresses? How can i make them on same block of address when the router
    is off because most of the time i turn off the router and dsl line but
    i want them to see each other eventhough the router is off.
    like this unit i am using. i can browse on the net but it cannot be
    seen by other computers.but its connected to the internet anyway...
    thanks in advance.
  6. Hope that is not serious...Talks x25? Feel free...:D
  7. Mark VB

    Mark VB Guest

    Sure, it can.
    Use fixed IP's on your computers and turn off DHCP.

    Mark Van Borm
  8. CWatters

    CWatters Guest

    yes I believe it's called subnetting but I might be wrong.

    How can i make them on same block of address when the router
    Normally you would set your network up so that all the PC get IP addresses
    from the router vis DHCP. If you want to turn the router on and off (why?)
    you could allocate each PC, the router and anything else (printer) static
    IPs in the range 192.168.0.x and all with the subnet mask
  9. Yes, it is subnetting. You assign subnets via the netmask:
    which means you could use from to (lowest and
    higest address goes away...)
    That'd be a 7-bit wide subnet, so it could be written
    You can divide your net into any portion that is dividible by a power of
    two (i.e 2-4-8-16-32-64-128 leaving respectively 126-62-30-14-6-2-2 IP's
    I seldomly see any reason for subnetting, unless you have more than a
    /24 bit ( subnet, in which cases windows uses ages for
    discovering its network neighbourhood. If you have under 254 machines, I
    see no point in subnetting. For security, use VLANs.

    Yes, and I suggest yo turn off dhcp in the modem/router if you turn it
    off. Enable a dhcp server somewhere else.
    Here is my dhcp setup:
    ddns-update-style none;
    default-lease-time 14400;
    option domain-name "";
    option domain-name-servers;
    option routers;
    subnet netmask {
    default-lease-time 14400;
    max-lease-time 172800;

    DHCP can be found on
  10. John

    John Guest

    In the sense that I've been successful in implementing Cisco's XOT
    (X.25 over TCP/IP) and writing programs for available battery-backed
    PC's to run constant traffic over a test network (4 Telematics nodes).
    The test network ran and collected performance statistics for almost a
    year. X.25 isn't that common in the US (other than the modified BX.25
    used by some telephone companies and specific sections of the US
    government), although it has seen much usage elsewhere in the world.

    Network diagram:

  11. Guest

    tnx, because as a beginner, i just want to see my network stations to
    see each other even the router is off.( just discovering, learning). by
    the way, i can see the ip adresses of each computer when i type
    ipconfig. but i dont know how to view the ip address of the router. and
    also how to change its ip address. please give me the concept of
    operation of a router.
    thanks in advance!!!
  12. Guest

    Thank you. by the way how can i turn off the DCHP>
    thnks in advance!!!
  13. CWatters

    CWatters Guest

    To configure the router you normally have to surf to a special web page
    built into the router itself. The instruction manual for the router will
    tell you how to do this.
    same as above.
    Skip the sections you know..
  14. CWatters

    CWatters Guest

    See the instruction manual for the router.
  15. Guest

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