Just checking this is correct

Discussion in 'Networking & Security' started by Jay_2, Feb 18, 2015.

  1. Jay_2

    Jay_2 2[H]4U

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    Cisco question

    I was setting up a 2960s 10G for iSCSI and was told that Cisco do not recommend setting the speed and duplex on each end of anything above 1Gbps. In the past anything like servers, switch to switch, switch to router I have always manually set speed and duplex to stop mismatch. Is the advice correct?
     
  2. TCM2

    TCM2 Gawd

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    Uhh, what? I have never manually set any speed/duplex for about, I don't know, 15+ years?

    Where do you get the idea that setting this manually is actually the correct advice?
     
  3. schizrade

    schizrade [H]ardness Supreme

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    Duplex is auto, do not mess with it.

    When was the last time you worked on a switch?
     
  4. Liger88

    Liger88 2[H]4U

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    Only time I set the speed/duplex was in the educational environment to familiarize yourself with the process of configuring everything similar to how you learn 10,000 years later how caveman once had to rub sticks together to get fire instead of using a match.

    Only other real reason I know people set things themselves is when there's a finicky card or bad cable where the connection is constantly being lost, but that's often times a bigger problem.
     
  5. Jay_2

    Jay_2 2[H]4U

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    So when connecting a switch to a router you guys never set the speed and duplex on both sides?

    Many many times I have walked into "our internet is slow" or "we have strange issues with failed downloads" it's always been due to the router and switch having a speed and or duplex mismatch when set to auto and tcp retransmits through the roof.

    I'm not talking about setting this for every port.
     
    Last edited: Feb 18, 2015
  6. TCM2

    TCM2 Gawd

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    I know this from 10Mbps times when you had AUI transceivers that didn't have autosensing, but Fast Ethernet and beyond? Never. It's such a mind boggling idea that you actually do this today.
     
  7. Jay_2

    Jay_2 2[H]4U

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    Strange you have never come across this then.
     
  8. Nicklebon

    Nicklebon Gawd

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    GE should never be set manually as doing so is a violation of the spec.

    Mismatches usually come about because one side is manually set while the other is auto. Both sides auto always unless you have a very good reason and then both sides are manual for speed that is 100 or 10.
     
  9. Jay_2

    Jay_2 2[H]4U

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    Perfect, that's the answer I needed, thanks.

    To be honest the issues I had with auto negotiations was 100Mbps connections, thinking back it was always 1841 and 3560s that I had this with as well.

    This backs up what you said

    http://etherealmind.com/ethernet-autonegotiation-works-why-how-standard-should-be-set/
     
    Last edited: Feb 18, 2015
  10. schizrade

    schizrade [H]ardness Supreme

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    Sure, 15 years ago.

    Manual duplex away then.
     
  11. Jay_2

    Jay_2 2[H]4U

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    Ok, thanks for the input.
     
  12. schizrade

    schizrade [H]ardness Supreme

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    lol, more than one person told you to leave it to auto. You could have just gone to google and looked it up.
     
  13. Jay_2

    Jay_2 2[H]4U

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    Ok, like I said, thanks for the input. What's with the slightly snide attitude here?

    Anyway, thanks to everyone who chipped in with advice.
     
    Last edited: Feb 18, 2015