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  • Loss of Internet Connectivity

    This one is really throwing me!
    Vista SP1 and also Server 2008 occasionally lose their internet connectivity, although maintain local connections. Visible sign is the globe drops off the networking icon in the tasktray, then opening Network and Sharing centre shows connection to the Network but not to the Internet.

    Pinging goes as far as the router but not further. No non-vista/2k8 PCs have experienced this issue

    Environment is Server 2003 providing DHCP and DNS but computer is not a domain member. Also Server 2008 Domain Controller with static IPs and local DNS, with forwarders. Internet access is via Netgear VPN/Firewall device to broadband modem (static external IP)

    Various repair options including "Diagnose and Repair", IPCONFIG/FLUSHDNS, disable one NIC on a dual NIC server and connecting to on-line help, but it seems to be very much chance which one works. Disabling IPv6 on the servers seems to make no difference.

    Google mentions issues with DHCP between Vista and XP but clearly this does not apply in this case.

    Aarrgghh. All help greatly appreciated.

    Tom
    Tom Jones
    MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
    PhD, MSc, FIAP, MIITT
    IT Trainer / Consultant
    Ossian Ltd
    Scotland

    ** Remember to give credit where credit is due and leave reputation points where appropriate **

  • #2
    Re: Loss of Internet Connectivity

    How occasionally are we talking? 5 minutes? Half a day? Once a week? When did it start to happen and were there any circumstances that you suspect?

    I'll make the rather safe assumption that the event logs have been duly combed, the firewall has been disabled (temporarily, for testing purposes only =) ), and Google has been consulted.

    How about comparing the running services from before the problem occurs to after the problem occurs? Have you rebuilt the tcp/ip stack? Installed the latest drivers for your NICs?

    All of those 'fixes' seem like just throwing haymaker punches at the problem... but if it works, who's complaining?


    EDIT: Is it possible to run the machine(s) in question in Safe Mode w/Networking for a while to see if the problem still occurs?
    Wesley David
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    • #3
      Re: Loss of Internet Connectivity

      So you can ping the gateway and then it stops?
      Is the gateway in the same subnet as the clients (eg server/workstation)?
      If yes, then he can find the IP by using broadcast so that does make sense.

      Can you do nslookup queries from an internet address which isn't in the DNS cache from the DNS server and local on the client?

      If I read your story correctly it sounds he is loosing it's gateway.
      You could try to add a static route to the gateway to see if this temporarily fix your problem.
      I'm not so sure if it's the IPstack because you still can contact any other locally attached client on the network, right?

      Other question, have you changed/checked the MTU size? It can give you really some weird issues.
      Marcel
      Technical Consultant
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      MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
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      • #4
        Re: Loss of Internet Connectivity

        Thanks, guys, for the replies.

        It seems to have no pattern but 2-3 times per day, but then again my laptop (Vista business) worked fine yesterday.

        As I'm in the middle of a major network rebuild, its not my top priority, but its worrying that a server can drop off like that, and seems to be fixed by disabling and re-enabling one NIC

        Will try some more tests over the weekend and see what happens, but it is definitely Vista/2K8 related as nothing else has reported any problems.
        Tom Jones
        MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
        PhD, MSc, FIAP, MIITT
        IT Trainer / Consultant
        Ossian Ltd
        Scotland

        ** Remember to give credit where credit is due and leave reputation points where appropriate **

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        • #5
          Re: Loss of Internet Connectivity

          OK, a partial update:
          On a 2008 Server, I saw it drop off line and then found one of the NICs (with static IPv4 address) was showing an APIPA address. I thought this was not possible with static addresses, but clearly something is rotten in the state of TCP/IP

          Disabled that NIC and tried pinging its (static) IP, and found I got a response, so clearly there is a rogue device, presumably not permanently connected, that is coming up on 192.168.0.1 Time for a search for anything with ICS enabled......

          I still dont know how the Vista boxes were losing it as well, as they were on different IPs.....
          Tom Jones
          MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
          PhD, MSc, FIAP, MIITT
          IT Trainer / Consultant
          Ossian Ltd
          Scotland

          ** Remember to give credit where credit is due and leave reputation points where appropriate **

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          • #6
            Re: Loss of Internet Connectivity

            1. rogue device interfering with the others
            2. UPnP acting up
            3. faulty switch
            ________
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            Last edited by DYasny; 6th March 2011, 19:00.
            Real stupidity always beats Artificial Intelligence (c) Terry Pratchett

            BA (BM), RHCE, MCSE, DCSE, Linux+, Network+

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            • #7
              Re: Loss of Internet Connectivity

              Have tried disabling the Link Layer Mapper and Responder, IPv6

              But still the same problem.

              Tom, the problem has now appeared up on my home network also.

              So, I don't think its a problem with the Router as the XP machines are working fine.

              Will have to try and see about updating the firmware of the VPN Router.

              Comment


              • #8
                Re: Loss of Internet Connectivity

                Sandmax, you have picked up on a different thread to your original one but we appear to have the same problem.

                From your other post we also appear to have a Netgear FVS338 so I dont know if thats a common factor or if its Vista/2K8 at fault.

                I'll update later today on the story of "Ossian Jones and the Rogue IP"
                Tom Jones
                MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
                PhD, MSc, FIAP, MIITT
                IT Trainer / Consultant
                Ossian Ltd
                Scotland

                ** Remember to give credit where credit is due and leave reputation points where appropriate **

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                • #9
                  Re: Loss of Internet Connectivity

                  Hope you have a bullwhip and can outrun giant rolling boulders. Have you run a MAC scanner to see if there are any unrecognized hosts on your network?

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                  • #10
                    Re: Loss of Internet Connectivity

                    Well, bullwhip in hand, I headed into the Cat6 jungle, dodging snakes (why does it have to be snakes ), boulders, packets and wild pings.....
                    and found a WAP I thought I had reconfigured to a different IP was still sitting on its default 192.168.0.1 So thats one problem fixed.

                    Still got the vista issues, though....
                    Tom Jones
                    MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
                    PhD, MSc, FIAP, MIITT
                    IT Trainer / Consultant
                    Ossian Ltd
                    Scotland

                    ** Remember to give credit where credit is due and leave reputation points where appropriate **

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                    • #11
                      Re: Loss of Internet Connectivity

                      Ah yes, the ever elusive ICMP echo reply. Rarely seen in the wild. Good luck.

                      P.S. It's always the snakes.

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                      • #12
                        Re: Loss of Internet Connectivity

                        OK, next problem tracked down:
                        The DHCP/main DNS server was on the same IP as a bit of telecoms equpment so thats changed now. Of course DHCP packets are broadcast, so we never spotted this until the server was off and a ping still came back.

                        With luck (and the bullwhip), this will start working properly soon.....
                        Last edited by Ossian; 27th June 2008, 07:33.
                        Tom Jones
                        MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
                        PhD, MSc, FIAP, MIITT
                        IT Trainer / Consultant
                        Ossian Ltd
                        Scotland

                        ** Remember to give credit where credit is due and leave reputation points where appropriate **

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