3 Replies Latest reply on Nov 22, 2011 10:05 PM by cruiser1

    SPT and SFT teaming


      The ANS whitepaper specify that SPT should be run on the network.


      Should the SPT run only between the switches, or do we also have some BPDU packets running between the server adapters and the connected switches.

        • 1. Re: SPT and SFT teaming

          Perhaps there are no responses because it is unclear what you are asking.  Do you mean STP rather than SPT?  You mention BPDUs which are associated with Spanning Tree Protocol (STP).  SPT is Shortest Path Tree which has to do with OSPF, a routing protocol.  STP is run only between switches to reduce the chance of a layer 2 switching loop occurance where there is more than one path to the root bridge.  It is a good thing like SFT (if you mean Switch Fault Tolerance).  Use them both.


          Scott Browning

          • 2. Re: SPT and SFT teaming

            Thanks for  helping me to precise my question.


            I understand the spanning tree is a good thing between switch to try to avoid loop. The question I ask is between the server ports and the switches ports.


            The network administrator had read the ANS documentation where it is stated that spanning tree is needed for SFT. He's now fearing that the team itself (the server NIC ports) will emits BPDU packets, which will be a problem because the server facing switches port are configured with BPDU Guard.

            • 3. Re: STP and SFT teaming

              I believe your admin mis-understood what what presented in the ANS document.  Spanning Tree Protocol (STP) should be running when using Switch Fault Tolerance (SFT), but it does not run on servers or workstations.  It only runs on switches and bridges.  The BPDUs are Bridge Protocol Data Units (a bridge being the precursor to a switch since STP pre-dates switches).  I am not familiar with any servers that generate BPDU frames.


              SFT takes care of fault tolerance on the servers and STP takes care of it on the switches.


              You are correct that PortFast on server facing switchports is something to consider, but receiving a BPDU on that interface will place the port into an errdisabled state.  It will not disable STP.  The connection to the server would be down until the admin re-enabled it - inconvenient, perhaps, but not likely to take your organization down.  Not enabling STP on the other hand, could shut your network down and cost many hours and dollars (read : http://www.cio.com.au/article/65115/all_systems_down/).