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Intermittent Network Issues

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  • Intermittent Network Issues

    We have a issue with our Server 2008 R2 Standard machine where it will have intermittent issues with the network connection. It does not actually disconnect from the switch or anything, like its a software issue blocking traffic in and out. It will do this for about 30 seconds-1 minute and most of the services will failover to the other server.

    We have a 2 server environment.

    Server 2003 R2 machine- runs AD, DNS, WDS, and DFS/DFSR.
    Server 2008 R2 machine- runs AD, DNS, DHCP, DFS/DFSR, and Exchange 2010

    The Exchange part will have an issue where it will say it can't find any Active Directory servers (both are GC servers). It has this issue at the EXACT same time that the DFS shares will failover to the 2003 machine. IIS is unreachable on the 2008 server.

    IPv6 is disabled on the 2008 machine. Its a BRAND New Dell PowerEdge T110 II with a Broadcom Gigabit NIC. We set the NIC speed manually to 1000 MBps Full (which is what the switch is). We disabled the Windows Firewall service and it seemed to stop having the issue, but when we had to shut down the server to change out the APC UPS it started having the issues again.

    We don't have another NIC to try in it. Since it actually isn't really disconnecting on the hardware level (the lights on the switch never go out) we like its a windows issue.

  • #2
    Re: Intermittent Network Issues

    Since you indicated that you have the port settings configured manually, you should most definitely go back to the switch and verify that the switch port and the NIC card are set to the same identical settings. Can you set them both back to Auto/Auto, just to see if this resolves the issue?

    -Take a look at the switch logs and see if there are any FCS errors on that port.

    -Make sure that you are running the latest supported drivers for the NIC.

    -Can you move the network cable to another switch port just to rule out a port problem?
    JM @ IT Training & Consulting


    • #3
      Re: Intermittent Network Issues

      It was set to Auto when the issues started occurring and we just recently changed it manually. We checked to see what it auto configured itself as before we set it manually. It does not do this all the times, just randomly. Sometimes it will be fine for a week or so but when we reboot it, it will start happening again.

      It is an unmanaged switch


      • #4
        Re: Intermittent Network Issues

        Enable IPv6


        • #5
          Re: Intermittent Network Issues

          - dell firmware for nic
          - dell drivers for nic
          - change cable
          - change switch port

          see if any of those help..
          Please do show your appreciation to those who assist you by leaving Rep Point


          • #6
            Re: Intermittent Network Issues

            I would say go with Broadcom for your NIC drivers. Agree with the cable and port change.

            Are you seeing any errors on the switch???

            Are you teaming the NIC's???

            What type of switch are you using???


            • #7
              Re: Intermittent Network Issues

              Enable IPV4


              • #8
                Re: Intermittent Network Issues

                The OP said IPv6 was disabled, so IPv4 must be on!!!
                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

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


                • #9
                  Re: Intermittent Network Issues

                  I am having the same symptoms on a 2008R2 standard as well.

                  Alan, in perfmon do your cpu and disk activity drop to zero during the outage as well?

                  I'm sure my problem is Windows based as this Server runs on a ESXi 5 platform with another server. During the outage all counters on the affected server drop to zero, but the other server on the same ESXi host is unaffected.

                  I have 2 NICs set up and both stop responding to pings at the same time, 2 different VNICs, Vswitches, connected to 2 different physical switches, yet the second Guest uses the same hardware without a hiccup.

                  Can you pin it to a time when it started? Anything change? Windows updates maybe?

                  No errors logged in Windows or VMWare either in my case.