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APIPA and USB modems

Discussion in 'Networks' started by Boycie, Nov 19, 2005.

  1. Boycie
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    Boycie Senior Beer Tester

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    Hi,

    I went to have a look at someones computer today that has a problem with internet connectivity. :(

    They have a USB ADSL modem which is correctly installed and with microfilters on both sockets. All was Ok until the computer wasn't used for about 2 weeks. Now, it will only sync up with the ISP if the phones are unplugged and then it is fine.

    I think it must be either a fault on the line or the telephone. Any other ideas? :blink

    Something else i noticed was that it is assigned a APIPA address within network connections of 169....... with no default gateway.
    Am i right in saying this is because there is no DHCP on the local network side (although the ISP issues a Public IP). The only way to communicate with it is via the software.
    I advised them to go for a router as they want to turn the computer off every night which means the USB modem booting up....
     
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  2. tripwire45
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    tripwire45 Zettabyte Poster

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    Ok, let me get this straight.

    They have one computer connected to the ADSL modem via USB. The fact that they are getting an APIPA address does indeed mean that they are configured to get an IP addy automatically but can't contact a DHCP server. On the LAN side, the ADSL modem should be handing out IPs (usually non-routable 192.168.0.*) The WAN side of the modem should be dynamically receiving a routable IP address from the ISP. Naturally, NAT is used to allow the PC to hit the Internet.

    It's weird that it can hit the Internet if you unplug the phones in the house. Could one of the filters have gone bad? Also, if the PC has an APIPA address, it probably means it's not able to connect to the ADSL device. When you unplug the phones and the PC can connect to the Internet, what is its IP address? It can't the the APIPA address.
     
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  3. Boycie
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    Boycie Senior Beer Tester

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    trip,

    The only way i could get it to connect at all today was with the phones unplugged.. this was with the APIPA address. :blink
     
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  4. tripwire45
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    tripwire45 Zettabyte Poster

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    I need to make sure I understand you correctly...you connected the conputer to the Internet while it was using an APIPA address? :blink

    Have you checked the DSL device's IP address configuration. Unless the gateway is also an APIPA device (extremely unlikely), I am baffled as to how this thing gets out on the Internet.
     
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  5. Jakamoko
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    Jakamoko On the move again ...

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    Boyce, it sounds like the set up is for the main PC with the modem to be the gateway, and set to use Internet Connection Sharing - is this right ? That would mean that if there was a prob with the internet connection, then ICS would not work properly, and any other PCs on the network would pick up APIPA addresses (remember the ICS / mini-DHCP comparison here).

    Coincidentally (or maybe not) as Trip says as above, it sounds like at least one filter has gone pear-shaped, hence having to unplug the phones before being able to connect.

    Once we are 100% clear on what is the case here, we will be able to help further. :)
     
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  6. Boycie
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    Boycie Senior Beer Tester

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    Thanks for the input guys.

    Yes, it would appear the filter(s) have gone bad.

    As for the APIPA :blink

    I am going there again tommorow as it needs a tune-up in general and a stick of RAM. SP2 with 256 is slow...
     
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  7. Bluerinse
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    Bluerinse Exabyte Poster

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    I think the APIPA thing is a red herring. It is a USB device and may just be functioning like an external modem. The fact that it works proves the configuration is fine. Focus your efforts on the filters Boyce.
     
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  8. Boycie
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    Boycie Senior Beer Tester

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    Went back there today with a new filter and all is well. :)

    Still showing an APIPA mind :blink

    Do you think it is because under connections it is showing up as a Local connection (there were 2, but i deleted the unused one) which windows expects to be dealt a class a,b or c address when the modem cannot provide a LAN address and has no NAT therefore connects directly to the net.....
     
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  9. Jakamoko
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    Jakamoko On the move again ...

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    Is the APIPA addy on the LAN connection of the PC connected to the modem, or on the other PCs connecting through the ICS ? And which PCs are getting online here ?
     
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  10. Boycie
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    Boycie Senior Beer Tester

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    Gav,

    That is the mad thing! There is only one PC, which obviously doesn't have or need ICS :blink
    And yes, the connection to the usb modem has the APIPA. I deleted the secound as it wasn't needed. :biggrin
     
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  11. Jakamoko
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    Jakamoko On the move again ...

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    OK, so firstly, the PC can get online then ?

    Secondly, under the connection properties (click the taskbar icon and check "Status") does it have a client IP and server IP ? I would imagine the client IP would be the APIPA addy and the server IP the one obtained from the ISP ?

    Boycey is exhibiting a slight vagueness at times that would suggest this modem may have originated from a T.I.T transaction !! :biggrin
     
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  12. Boycie
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    Boycie Senior Beer Tester

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    TIT? Sorry Gav you have lost me !
     
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  13. tripwire45
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    tripwire45 Zettabyte Poster

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    You should see an online indicator in the lower right-hand corner of the systray

    Right-click it and then click Status.

    The Local Area Connection Status box opens.

    Click the Support tab

    You'll see some information including

    Address type (DHCP or Static)
    IP Address
    Subnet Mask
    Default Gateway

    Click the Details button. You should see information such as in the example below.

    Physical Address: 00-0D-56-AF-EF-E8
    IP Address: 192.168.1.147
    Subnet Mask: 255.255.255.0
    Default Gateway: 192.168.1.1
    DHCP Server: 192.168.1.1
    Lease Obtained: 11/21/2005 8:12:02 AM
    Lease Expires: 11/22/2005 8:12:02 AM
    DNS Servers: 192.168.2.5, 192.168.2.6
    WINS Server: 192.168.2.5
     
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  14. Jakamoko
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    Jakamoko On the move again ...

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    Trotters' Independent Traders !!! :rolleyes:
     
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  15. Bluerinse
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    Bluerinse Exabyte Poster

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    Ha I never realised the acronym was TiT :biggrin

    For Trip: Trotters independent Traders are the company that Dell Boy and Rodney ran in Only Fools and Horses. Boyce was a big star in that show.
     
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  16. tripwire45
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    tripwire45 Zettabyte Poster

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    Oops. :oops: I misunderstood what Boyce misunderstood. :crawls under a rock:
     
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  17. Boycie
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    Boycie Senior Beer Tester

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    LOL, TIT :biggrin - i remember the episode where Del got rodney a traffic warden uniform and said he had it made especially for trotter watch!

    As for the local connection stats Gav, it is rather strange. There were 2 LAN connections under connections. One wasn't being used so i deleted it....
    The other is the one the usb modem is connected to and has the APIPA info. Yes there is an icon in the sys tray showing the up/downstream info. IF you click on it all the configuration is "greyed out" I can't help thinking the ISP has given the modem as a freebie due to their way of doing things :dry
     
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  18. Jakamoko
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    Jakamoko On the move again ...

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    What happens if you remove the other connection and reboot ? I would also be tempted to uninstall the modem as well and then reboot and reinstall it. I really dont think there's anything more serious than clumsiness going on here, as otherwise everything seems to be doing what it should.
     
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  19. Boycie
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    Boycie Senior Beer Tester

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    i think you are right Gav.
    As it happens they want to migrate ISP's so i have advised a single port router with the swop. They will get the £40 ish quid back after 3 months of saving from their current direct debit....
     
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  20. Bluerinse
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    Bluerinse Exabyte Poster

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    Boyce, when you do an IPconfig. Has the USB adapter, the one with the 169.254.x.x address got a default gateway assigned?

    APIPA does not hand out gateway information, so if there is a gateway (the routers private IP) the IP address is being leased by the router.

    Although 169.254.x.x is the APIPA range, it is a perfectly valid range which can be used in LANs. That is why it is there :biggrin

    Again, if it aint broke, don't fix it :dry
     
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