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Could do with some assistance on IP addresses

Discussion in 'Firewalls and Networks' started by dave71, Sep 3, 2014.

  1. dave71

    dave71 Established Techie7 Member

    Hello
    We seem to have occasional IP address conflict on our home network and i could do with a bit of help. Ive been reading up on the issue but don't really understand a lot of the terminology, being an IT novice.

    We currently have
    1 mac mini hard wired to router (osx 10.9.4)
    1 apple tv (hard wired to router via 5 port switch)
    1 xbox (hard wired to router via 5 port switch)
    1 youview TV box (hard wired to router via 5 port switch)
    1 wireless extender (hard wired to router via 5 port switch)
    2 ipads
    1 ipod
    1 iphone
    1 mac book
    3 windows 7 laptops (2 of which are not used much and powered down when not in use)
    1 wireless airport printer
    6 users - source of 99% of errors

    Majority of the above are in standby mode when not in use. Upon wakeup my mac mini is the one that seems to have the most problems, with the iPads second. I've occasionally checked to see what IP addresses are assigned to what devices but haven't really checked everything in one go and made a note.

    Switching off my printer fixes the issue on occasions with my mac but I would like to learn a bit more and come up with a long term fix.

    The iPads usually require me to hit 'forget this network' and reconnect when the wireless won't connect, which works but I'm not sure if thats an IP address issue as there are no messages, just no working wifi connection.

    Not really had any issues with the rest of the devices.

    I am a novice and could do with some simple advice with a brief overview on how everything work and how IP addresses are assigned etc.

    Thanks

    Dave
     
    Last edited: Sep 3, 2014
  2. dave71

    dave71 Established Techie7 Member

    just looked these IP addresses up through my router, all is running fine at the moment. What should i look for if things go wrong, will i see if 2 devices are trying to use the same IP address or would one not be visible
    mac mini - 1.2
    apple tv - 1.3
    ipad mini - 1.5
    iphone - 1.7
    youview tv box - 1.12
    mac book - 1.13
    ipad - 1.15
    wifi printer - 1.17
    wireless extender - 1.254

    I assume the extender has a fixed IP address with it being such a high number
     
  3. Digerati

    Digerati Super Moderator Techie7 Moderator

    Users may be the source of most of your errors, but users don't count. It is all about the networked hardware devices - or more accurately, their NICs (network interface cards).

    How do you know you are getting "conflicts"? Are you getting errors that indicate a "conflict"? Typically a "conflict" happens when a networked device (computer, printer, NAS, etc.), is trying to use the same IP address as another device that is already using that IP address.

    This happens a lot with DHCP and NAT. This is when your router "dynamically" assigns IP addresses to your devices when they attach - as opposed to "statically" (permanently) assigned IP addresses.

    It also happens if you portable devices frequently connect to different networks, get a IP, then try to use that IP next time you connect to your network.

    First thing I would do is look in your router's admin menu and see if the "number of connected devices allowed" is limiting your access. If, for example, your computer is set to allow a range from 192.168.1.1 to 192.168.1.10 (typical examples), you have too few available IP addresses so you may need to change the top value to 192.168.1.15 or maybe .20 in case you have company come over.

    Then you "should" be able to get all your devices connected at once and then you "should" not have this problem - IF these device only connect to your network. If they get a different IP from another network, you may get a conflict again when you return to yours.

    Alternatively, you can manually assign a "static" IP address for each device.
     
  4. dave71

    dave71 Established Techie7 Member

    Thanks for the reply. The router has a range of addresses available from 192.168.1.2 to 192.168.1.254, so there's plenty available. Quite a few of the devices do leave the house and log onto other networks so may be the cause, also the printer may be switched on whilst a device is on standby, would this cause some confusion over address conflict.

    the messages i get on my mac mini/macbook is "another device is using the same IP address" and i can't get online. Would setting a static IP addresses on my mac mini , apple TV and printer be the best option, something high well away from other devices. I'm not sure how to do this so would need guidance, I'm guessing my printer would need to be hooked up via usb to do so.

    As most of the other devices leave the house and access other networks - am i right in assuming they can't have a static IP address
     
  5. Digerati

    Digerati Super Moderator Techie7 Moderator

    That depends on the "true" power state the printer is in when "off". If truly and completely shutdown, with no standby power applied to the printer's NIC, then your router may "release" the IP assignment, and return that address to the available pool. Then when the printer is powered on again, it requests a new IP assignment - and may end up getting a different IP.

    If the printer remains in standby mode, it should maintain its network connection settings, thus not lose its IP. Since you told us nothing about your printer, other than it is networked via wireless, I cannot tell you how to set it up. But I would think you don't need to do anything.

    Assigning static IP addresses should resolve this. However, the numbers can be adjacent or spread apart, and do not have to be high in the range, but can be, if you want.

    How you do it depends on the device and your router. In my Netgear router, it is done through the "Address Reservation" feature by assigning a specific IP address to a specific MAC address and device name. The MAC address is [supposed to be] a unique hexadecimal identifier burned into the firmware of the NIC by the manufacturer of each networked device. Then, whenever that specific device connects to your network and requests an IP assignment through your router, the device will always receive the same IP address. In most cases, you don't have to change anything on the device to use a static IP assignment from the router (except maybe reboot to flush the IP from "the other network") - your router does it all.

    By stiff definition, it is not really static since the individual devices are still set for dynamic (DHCP) IP assignment. When connected, they just ask for any IP address available. But your router, recognizing the unique MAC address and device name, will always assign the same IP to that MAC address/device - thus avoiding conflicts with other devices.

    That said, you certainly can configure each device to use a static IP address too - but how depends on each device. In other words, read the manual!

    While I totally disagree with the first sentence, you can see how to configure your Windows based computers here.

    If you can see other wireless networks from your house, others can see your wireless network - and regardless, a badguy sitting in his car down the street can see your wireless network. So I would limit that IP range for general security. If you have 10 devices, you might want to limit that range to 15 or less - or even 10 for best security. That will prevent a nosey neighbor from guessing your passphrase and piggybacking onto your network - potentially using your ISP assigned IP address to send spam, malware, or for other nefarious deeds - like snooping around on your attached computers. :( Obviously, have a strong passphrase that is not your dog's name or something a neighbor could easily guess.
     
  6. dave71

    dave71 Established Techie7 Member

    Great! Ive found the reserve IP address facility so i'll read up on that and give that a go first as it may resolve the issue. My mac mini is the device i use most, and IMO has priority, so it'll be the first one to try. I'll also look further into static IP addresses now i have a it more understanding, unfortunately I've yet to discover which is the correct process for configuring my Mac.

    The network password is a generated one so that's secure enough, but again i'll look into reducing the number of addresses available.