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  • NIC fault tolerance

    Hi

    As mentioned near the end of this thread, the network engineer made a recommendation that we install a second cable to introduce redundancy/fault tolerance.

    The servers that will use both these cables comprise:
    Windows Storage Server 2008
    Windows Server 2008 standard
    Windows Server 2012
    Windows Server 2012 R2

    Presently, these servers are connected to an 8 port desktop switch which is connected to an RJ45 connection. The CAT5e cable from the RJ45 socket then terminates at a patch panel.

    A second cable will be installed next to the present cable and will connect to the same patch panel.

    My question is what is best practice regarding configuration of the network cards. I have read that only Server 2012 onwards supports teaming, and that the use of teaming on earlier versions of Windows can introduce more problems that it solves.

    Firstly, definitions. As I understand it 'teaming' groups network cards together so that they appear as one interface. This is also referred to as 'Link Aggregation' or 'Load Balancing and Failover'.

    Because we will have two physical cables from the server space to the patch panel, would it better to assign separate IP addresses to each network card and then rely on Round Robin to ensure that both cards are equally utilised? This described in section 2.3 of this blog post. This would seem to be a simpler solution.

    The priority is to provide fault tolerance, not extra bandwidth.

    Anyone have any thoughts about this?
    A recent poll suggests that 6 out of 7 dwarfs are not happy

  • #2
    Re: NIC fault tolerance

    The setup would look like this:

    A recent poll suggests that 6 out of 7 dwarfs are not happy

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    • #3
      Re: NIC fault tolerance

      "Desktop" switches typically do not handle any type of teaming. You can still configure the server end of the connection as a (non-LACP) team, but the load balancing will only work in one direction (server to clients). You'll still get fault tolerance, though; if one link goes down, the other will take over.

      Windows Server 2008 does not have native support for NIC teaming, but certain NIC vendors (like Broadcom) have drivers that can create teams of identical NICs. Same goes for server manufacturers like HP.

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      • #4
        Re: NIC fault tolerance

        By the way, I see you have one cable from each switch going to a patch panel. What's at the other end of that connection? Another switch?

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        • #5
          Re: NIC fault tolerance

          Thanks. Yes, the patch panel's 48 ports feed two 24 port switches.

          But, I've just been reading this proviso which poo-poo's the idea I set out above.

          I'm still researching so feel free to post further info as this is new to me.
          A recent poll suggests that 6 out of 7 dwarfs are not happy

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          • #6
            Re: NIC fault tolerance

            Originally posted by Blood View Post
            But, I've just been reading this proviso which poo-poo's the idea I set out above.
            No, it doesn't.

            The scenario described in the article is one where teaming is not used, and instead two NICs are connected to the same L2 network and are assigned different IP addresses in the same IP network or subnet.

            A team, on the other hand, will act as one NIC with one IP address.

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            • #7
              Re: NIC fault tolerance

              Thanks, but in the illustration above I was envisioning that each of the NIC's has a different IP address (8 IP addresses in total), all 192.168.0.xx

              I have one Windows Server 2008 and one Windows Storage Server 2008 machines. The official line from Microsoft is that 2008 does not support teaming.

              I wonder if I can have a mix. Teaming on the 2012 boxes. and...

              I don't know at which point teaming becomes a problem for Server 2008. Does anyone use teaming on their 2008 servers?

              Thanks for the help - it makes me think about this and to consider other options etc.
              A recent poll suggests that 6 out of 7 dwarfs are not happy

              Comment


              • #8
                Re: NIC fault tolerance

                Like Ser Olmy said, Windows 2008 does not natively support teaming but most server grade NIC (and their drivers) do support it.

                I've successfully used Broadcom and Intel NIC teams on Windows 2003 and up.

                If you have your switches in a stack the the best throughput and fault tolerance would be to setup LACP teams. If your switches aren't stacked then you'll have to use the switch independent teaming on the server.

                I would stay away from using DNS round robin as your load balancer. You get no fault tolerance with that setup.
                Regards,
                Jeremy

                Network Consultant/Engineer
                Baltimore - Washington area and beyond
                www.gma-cpa.com

                Comment


                • #9
                  Re: NIC fault tolerance

                  Thanks a lot, Jeremy.

                  I've learnt a lot more about this now. I've also checked the servers and they all seem to use Broadcom NIC's so I'll make sure they are using the latest drivers and that the latest BACS software is also installed.

                  Cheers!
                  A recent poll suggests that 6 out of 7 dwarfs are not happy

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