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Need simple networking help please

Discussion in 'Networking & Security' started by Black Panther, Feb 26, 2012.

  1. Black Panther

    Black Panther Senior Moderator™ Staff Member

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    When the router/switch at bottom right was connected to 'old modem' (green) pc1, pc2 and pc3 had good wired internet access.

    Now the 'old modem' has been replaced by the Belkin (top left) which is a modem and router in one.

    It's connected, wired, to the router/switch which in turn is connected, wired, to pc1, pc2 and pc3.

    Thing is that now the Belkin is supplying internet to the 2 laptops upstairs (whether wired or through wifi) but pc1, pc2 and pc3 remain offline notwithstanding being connected through wire and not wireless.

    We tried changing the IP to remove any possible conflict but so far nothing has worked.

    What do you think is the issue here?

    Thanks.

    [​IMG]

    Edit: Note laptop 1 and laptop 2 used to get good wifi connection with 'old modem' connected to router/switch before belkin was bought, too... :confused:
    Last edited: Feb 26, 2012
  2. nick_1992

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    Sounds like your running on 2 subnets (or trying to) try maybe setting up the old router as a access point and not use the WAN port. I had to do with dlink equipment so i don't know you your equipment works exactly.
  3. Black Panther

    Black Panther Senior Moderator™ Staff Member

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    We're not using the WAN port. I'm not currently in the same physical location to check everything out, but dad assured me that he connected the 'router/switch' to the 'belkin' just as if it was another pc. So I guess it's not through the WAN port but through one of the others.
  4. Kreij

    Kreij Senior Monkey Moderator Staff Member

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    Make sure that the default gateways for the PCs are the IP address of the new modem.
    If you are using DHCP for everything you may have to refresh the "lease" so they re-establish the correct parameters that the modem is dishing out.
  5. _JP_

    _JP_

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    BP, is the cable that is connecting the Belkin to the Router/Wired Switch a crossover? ;)
  6. nick_1992

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  7. Black Panther

    Black Panther Senior Moderator™ Staff Member

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    No, just regular, not crossover. It's very long though, say over 30 meters (90 feet). Which is the main reason for the wired connection over wireless for pc1, pc2 and pc3...
  8. Rhyseh

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    A few things:

    When you are interconnecting devices such as switches or routers they connect by what is known as a trunking mode rather than the standard client access mode. Now due to the fact that these trunked devices send and receive information on the same pins a standard straight through cable may not work (many devices are intelligent enough to combat this but I digress). To combat this you should use a crossover cable to interconnect devices, if you don't want to re-run the cable you can easily create a crossover adapter if you have 2 RJ45 jacks.

    Additionally ensure that your other current switch connecting pc1, 2 and 3 is not acting as a DHCP server. If your device has this functionality ensure that it is configured as a DHCP relay from the Belkin device.

    Ensure that your switch/wireless access point has an IP address on the same subnet as the Belkin router.

    Additionally if you still have the old modem/router connected to the switch make sure that the DHCP functionality is disabled.

    If none of these work then start troubleshooting the setup using the OSI model:

    http://bfindarto.wordpress.com/2008/03/12/use-osi-model-to-troubleshoot-networks-cool/
  9. _JP_

    _JP_

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    So, your the Belkin is connected to the other Router/Switch by the Switch ports. If that's so, to connect two Switches together, you need to use a crossover cable, otherwise the connection will not be possible.
  10. Black Panther

    Black Panther Senior Moderator™ Staff Member

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    Are you guys sure that the cable needs to be a crossover one?

    We eliminated the "old router" (the one which was connected to 'old modem'), and instead of it put a simple Edimax ES3208P Switch. It's only a switch, without router.

    Now if we connect a pc wired directly from the Belkin router there is an internet connection.

    However, if we connect the Belkin to the Edimax switch, and then Edimax switch to the same pc there is no connection.

    :confused:

    [​IMG]

    All the cables above are not crossover.
  11. _JP_

    _JP_

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    I know it will be a pain in the neck because, as you said BP, the cable is 30m long. But, to make two switches communicate (in fact, any two equal network devices), it needs to be done using a crossover cable.
    What you described is the exact behavior of what happens when you connect two switches using a regular ethernet cable (Direct cable, or whatever the stores call it).
  12. Completely Bonkers New Member

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    I'm going for faulty cable. One or more of your cables is bad/damaged. Some devices "can cope" and others can't. It might be intermittent depending on how the wire was just flexed. Are all these cables strictly CAT5e or better? Perhaps you have a mix of old and new cables, or home connected plugs not factory connected ones. Could one or more wires within the cable be damaed or not connected properly, perhaps hanging high? Fault might be "more present" depending on whether the RJ45 socket is earthed or not.

    >> New cables

    It's not "crossover" issue. The ES3208P is autosensing PnP crossover or straight. So either the 3208P is dead, or your cables are at fault.
    Black Panther says thanks.
  13. Black Panther

    Black Panther Senior Moderator™ Staff Member

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    Well... both cables work when tested separately.

    The very long cable works when connected between Belkin and pc (without switch).

    The short (5 ft) cable works when connected between Belkin and pc as well.

    It's only when there's the Edimax switch in the middle that something's going wrong.. Or when there was the other router/switch..
    The Edimax is new, we put it there to simplify things instead of using another router...
  14. brandonwh64

    brandonwh64 Addicted to Bacon and StarCrunches!!!

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    I didnt read through the whole thread but here is a post from a similar thread and this would give you an idea of a typical structured private network


    Guttboy and Black Panther say thanks.
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  15. Black Panther

    Black Panther Senior Moderator™ Staff Member

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    So, no need for a crossover cable?
  16. brandonwh64

    brandonwh64 Addicted to Bacon and StarCrunches!!!

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    You should not need a cross over cable if you are connecting a router to a unmanaged switch. On your wireless router, Connect the modem in the WAN/Internet port and the switch into port 1. This will give all other ports on the switch direct connection to the router's DHCP pool.
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  17. Completely Bonkers New Member

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    In your first picture, what exactly is the blue box called router/wired switch?
  18. brandonwh64

    brandonwh64 Addicted to Bacon and StarCrunches!!!

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    I was wondering that as well. It also looks like you have two router/switch icons in your drawing. Do you have two routers or two switches?

    Also can we get model numbers of these two devices
    Crunching for Team TPU
  19. Kreij

    Kreij Senior Monkey Moderator Staff Member

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    Brandon is right, you should not need a x-over cable as switches have auto-detected that for years. (I don't use them anywhere on my work network and can connect the switches using any cat5 port)

    It sounds like DHCP shennanigans. I would make sure only one device is set up to dish out IP addresses and that all the other devices are set up to be a DHCP client.
    Easiest way to tell is to run "ipconfig /all" on the computers and see if they are in the same sub-net and using the correct gateway.
    Remember that if a computer is set to use DHCP and is turned on before the device that issues the IP addresses and gateway, Windows will assign a random IP address. Turning on the DHCP server will not automatically update the computer.
  20. Black Panther

    Black Panther Senior Moderator™ Staff Member

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    The blue box called Belkin modem/router or Belkin router is a Belkin N+ Wireless ADSL Modem Router Model F5D8635UK4A. Here's a review of it.

    [​IMG]

    It's the blue box with the two antennas, and it's there in both my OP post diagram and in the other diagram a couple of posts later.

    In the OP apart from this Belkin I was using another router as a switch (I think it was a Conceptronic?). But then we eliminated this other router which we were using as a switch and instead used an Edimax ES3208P (which is only a switch and not a router).

    [​IMG]

    We did it to simplify things. And we also connected only one pc to it, to get internet connection to it first... then we'll see for the other 3 pc's...
  21. Munki

    Munki New Member

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    You could just set all IP addresses static to check for DCHP problems.
  22. Black Panther

    Black Panther Senior Moderator™ Staff Member

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    Kreij, I think my dad turned off or disabled DHCP. That's wrong?

    ____________________

    Everything works fine as long as we use the cable direct from the Belkin to the pc at the workplace. The issue only arises once we put the switch in between.
    But a switch is indispensible since we need to connect 3 other pc's to share the same office network (and internet connection).

    If we didn't need more than one pc I'd have put the cable direct to the one pc, without a switch, and there'd be no issues.
  23. Kreij

    Kreij Senior Monkey Moderator Staff Member

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    Not if he has all of the machines using static IPs and gateway addresses.
    If the DHCP server is disabled for the wired network and the PCs are still trying to use it, they will get no information and just use some random values.

    You said that the PCs can't see the internet when the switch is inline ... can the PCs see the router when the switch is part of the network? (ping, tracert)

    It's odd as an unmanaged switch should not cause problems unless it is bad (bad port(s) or it's toast) or the cabling is bad.
  24. Black Panther

    Black Panther Senior Moderator™ Staff Member

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    He didn't try ping or tracert (hey dad if you're reading this go Start, type cmd, click enter, then in the black box type ping OR tracert followed by the IP address of the Belkin and see what you get...) but when we were using the Conceptronic router (instead of Edimax switch) the connection was without internet but it identified the network.

    Now using the Edimax switch on the "Network and Sharing Center" in the CP it shows up as an "unidentified public network". Something's not right...
  25. brandonwh64

    brandonwh64 Addicted to Bacon and StarCrunches!!!

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    If you dad had turned off DHCP then I would check to see if you have statically set each machines IP address, subnet mask, and default gateway.

    These would be like

    PC1
    IP: 192.168.1.100
    SM: 255.255.255.0
    DG: 192.168.1.1

    PC2
    IP: 192.168.1.101
    SM: 255.255.255.0
    DG: 192.168.1.1

    PC3
    IP: 192.168.1.102
    SM: 255.255.255.0
    DG: 192.168.1.1

    EXC......
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