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Hardware Thread, How to test network speeds? in Technical; I have a core switch 3 com model : 3Com Switch 5500G-EI 48-Port Software Version 3Com OS V3.03.02s56 It has ...
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    kennysarmy's Avatar
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    How to test network speeds?

    I have a core switch 3 com model :
    3Com Switch 5500G-EI 48-Port Software Version 3Com OS V3.03.02s56

    It has connected to it via UTP two 3Com Baseline Switch 2948 Plus's
    These are connected to the core switch via two UTP cables trunked for extra bandwidth....I've had nothing but problems with clients doing GPO updates connected to the 2948's so decided to do some testing with a spare Allied Telesis switch.

    I get exactly the same issues with the AT switch as I do the 3 com switch.
    See attached screenshot....

    group policy infrastructure issue thro 3 com switch.jpg

    If I connect the clients direct to the core switch (5500G) then all works fine every time.
    See attached screenshot

    group policy infrastructure fixed when using AT switch.jpg


    I thouhgt initially the issue was with the 3 com edge switches but since the AT edge switch does the same now I'm not convinced.

    My next trial is going to be to connect the AT switch to the core not using copper but using a fibre lead and SPF modules.

    If anyone else can offer any suggestions...

    How could I test the network speeds from the clients as they are now going through the AT switch before I uplink it with copper?

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    iperf, windows compiled version is older than the latest

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    kennysarmy's Avatar
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    Thanks.

    Current network speed between client and server using iperf is:
    93.2 Mbits/sec

    That seems OK to me....need to retest when switch is connected via fibre.

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    I would check duplex settings on the link between the core and edge switches. Also make sure the trunked connection is actually configured as a trunk. Have you tried it with a single copper link instead of the trunked pair?

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    kennysarmy's Avatar
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    Quote Originally Posted by keithu View Post
    I would check duplex settings on the link between the core and edge switches. Also make sure the trunked connection is actually configured as a trunk. Have you tried it with a single copper link instead of the trunked pair?
    Thanks for your suggestion:

    The edge switch is trunked:

    Port State Enabled
    PVID 1
    Flow Control Disabled
    Speed Auto[1000M]
    Duplex Auto[Full]


    This connects to the core switch which settings are:

    Port State Enable[Active]
    PVID 1
    Flow Control Disable
    Link Type Trunk
    MDI Auto
    Speed Auto[1000]
    Duplex Auto[Full]
    Max MAC Count No Limit
    Jumbo Frame Disabled
    Port Isolate Disabled
    Broadcast Suppression 3000(pps)
    Last edited by kennysarmy; 29th June 2010 at 10:28 AM.

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    Eliminate the trunk first, sounds to me like that might be the issue.

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    kennysarmy's Avatar
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    I have attached the AT switch using SFP modules and a fibre patch lead to one of my 3 com fibre core distribution switches, these are:
    3Com Switch 5500G-EI SFP 24-Port Software Version 3Com OS V3.03.02s56

    I am going to do some testing with GPO updates today on some test PC's and see if this works OK.

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    kennysarmy's Avatar
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    UPDATE:

    Connecting the AT (edge) switch to the CORE via spf modules/fibre patch leads : WORKS.

    I did think this might isolate the problem as suggested above to the PORT TRUNKING - however, when we tested the AT switch connected to the 3-com CORE switch 5500G-EI 48 by just a single UTP lead we STILL HAD PROBLEMS WITH GPO updates....

    Any suggestions as to how to proceed?

    Regards.

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    I don't think that this is network speed related. This kind of error usually happens when the network card takes to long to get an IP address and Windows gives up waiting and plows on without it. With XP there was an old disable mediasense trick that made it wait until it had an IP before proceeding but Vista+ are far more robust and have never needed kind of fix in most situations.

    I think that you problem could be to do with STP (spanning tree protocol) being enabled on the prts of your switch used by the client computers, this can put the port into a lock down for around a minute with no access as a safety measure against network loops. If it is on in the edge switchs there should be a client port mode for STP that only isolates for 5 seconds which should let the system pick up the IP address quickly enough and still provide a bit of protection.

    If this is not the cause I would look at using something like Wireshark to see what is going on directly on the network and see if it is the machines not being able to send out DHCP requests eairly enough or if it is simply not getting a quick enough responce from the DHCP server.

  11. Thanks to SYNACK from:

    kennysarmy (30th June 2010)

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    Thanks.

    I have researched further on the web and found this snippet....is it accurate ?

    Spanning tree should be enabled on the links between switches, and
    disabled on those to the servers.

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    This depends on who you listen to, STP should be setup on links between stitches and should generally be set to client port mode on all other ports. It should be safe to disable it on your server ports as those are unlikely to be looped back and will be the first ones you check anyway.

    For testing I would just disable it on the client ports of a few machines experiencing the issue and see if that resolves it, if it does I would still look to put it into client port STP mode which should still work but afford you some extra protection.

    Using STP allows for multiple redundant links between switches and also helps prevent broadcast storms which will bring your network to a standstill if there is a loopback. If you are using STP though you do need to have the core switch setup with the highest priority when using multiple redundant links otherwise it can lead to some very strange traffic flow.

    To work the network does not specificly need STP enabled, it just gives you the extra features and protections meantioned above.

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    Yes that is correct, ideally you should disable the STP on the access ports i.e. ports that connects to workstations, servers, printers or any other end device. It should be enabled for switch to switch ports. in Cisco this is called portfast which put the port into forwarding mode immediatly and does not wait for the loop detection process to complete.

    Ash.
    Last edited by spc-rocket; 30th June 2010 at 12:33 PM. Reason: spelling correction

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    3-com : edge switch 1 looks like this when I check the GUI under spanning tree...

    Port Status Path Cost Edge Port State Link Type Port Priority
    1 Enabled 200000 Disabled Discarding Shared 128
    2 Enabled 200000 Disabled Discarding Shared 128
    3 Enabled 200000 Disabled Discarding Shared 128
    4 Enabled 200000 Disabled Discarding Shared 128
    5 Enabled 200000 Disabled Discarding Shared 128
    6 Enabled 200000 Disabled Discarding Shared 128
    7 Enabled 200000 Disabled Discarding Shared 128
    8 Enabled 200000 Disabled Discarding Shared 128
    9 Enabled 200000 Disabled Discarding Shared 128
    10 Enabled 200000 Disabled Discarding Shared 128
    11 Enabled 200000 Disabled Discarding Shared 128
    12 Enabled 200000 Disabled Discarding Shared 128
    13 Enabled 200000 Disabled Discarding Shared 128
    14 Enabled 2000000 Disabled Forwarding Point to Point 128
    15 Enabled 200000 Disabled Discarding Shared 128
    16 Enabled 200000 Disabled Discarding Shared 128
    17 Enabled 200000 Disabled Discarding Shared 128
    18 Enabled 2000000 Disabled Forwarding Point to Point 128
    19 Enabled 200000 Disabled Forwarding Point to Point 128
    20 Enabled 200000 Disabled Discarding Shared 128
    21 Enabled 200000 Disabled Discarding Shared 128
    22 Enabled 200000 Disabled Discarding Shared 128
    23 Enabled 2000000 Disabled Forwarding Point to Point 128
    24 Enabled 10000 Disabled Forwarding Point to Point 128
    25 Enabled 20000 Disabled Forwarding Point to Point 128
    26 Enabled 200000 Disabled Discarding Shared 128
    27 Enabled 200000 Disabled Discarding Shared 128
    28 Enabled 200000 Disabled Discarding Shared 128
    29 Enabled 200000 Disabled Forwarding Point to Point 128
    30 Enabled 200000 Disabled Discarding Shared 128
    31 Enabled 200000 Disabled Discarding Shared 128
    32 Enabled 200000 Disabled Discarding Shared 128
    33 Enabled 200000 Disabled Discarding Shared 128
    34 Enabled 200000 Disabled Discarding Shared 128
    35 Enabled 200000 Disabled Discarding Shared 128
    36 Enabled 200000 Disabled Discarding Shared 128
    37 Enabled 200000 Disabled Forwarding Point to Point 128
    38 Enabled 2000000 Disabled Forwarding Point to Point 128
    39 Enabled 200000 Disabled Discarding Shared 128
    40 Enabled 200000 Disabled Forwarding Point to Point 128
    41 Enabled 200000 Disabled Discarding Shared 128
    42 Enabled 20000 Disabled Forwarding Point to Point 128
    43 Enabled 200000 Disabled Forwarding Point to Point 128
    44 Enabled 200000 Disabled Discarding Shared 128
    45 Enabled 20000 Disabled Discarding Point to Point 128
    46 Enabled 20000 Disabled Forwarding Point to Point 128
    47 Enabled 20000 Disabled Discarding Point to Point 128
    48 Enabled 10000 Disabled Forwarding Point to Point 128


    Ports 24 & 48 are the trunk to the 5500 core switch...

    Anyone know if this looks right or wrongly setup?
    Cheers.

  17. #15
    kennysarmy's Avatar
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    Amended and now looks like this:

    1 Disabled - - - - -
    2 Disabled - - - - -
    3 Disabled - - - - -
    4 Disabled - - - - -
    5 Disabled - - - - -
    6 Disabled - - - - -
    7 Disabled - - - - -
    8 Disabled - - - - -
    9 Disabled - - - - -
    10 Disabled - - - - -
    11 Disabled - - - - -
    12 Disabled - - - - -
    13 Disabled - - - - -
    14 Disabled - - - - -
    15 Disabled - - - - -
    16 Disabled - - - - -
    17 Disabled - - - - -
    18 Disabled - - - - -
    19 Disabled - - - - -
    20 Disabled - - - - -
    21 Disabled - - - - -
    22 Disabled - - - - -
    23 Disabled - - - - -
    24 Enabled 10000 Disabled Forwarding Point to Point 128
    25 Disabled - - - - -
    26 Disabled - - - - -
    27 Disabled - - - - -
    28 Disabled - - - - -
    29 Disabled - - - - -
    30 Disabled - - - - -
    31 Disabled - - - - -
    32 Disabled - - - - -
    33 Disabled - - - - -
    34 Disabled - - - - -
    35 Disabled - - - - -
    36 Disabled - - - - -
    37 Disabled - - - - -
    38 Disabled - - - - -
    39 Disabled - - - - -
    40 Disabled - - - - -
    41 Disabled - - - - -
    42 Disabled - - - - -
    43 Disabled - - - - -
    44 Disabled - - - - -
    45 Disabled - - - - -
    46 Disabled - - - - -
    47 Disabled - - - - -
    48 Enabled 10000 Disabled Forwarding Point to Point 128


    going to test GPO updates via this switch shortly...

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