Re: Poor network performance: a lot of timeouts

From: Vinny Abello (vinny_at_tellurian.com)
Date: 05/31/05

  • Next message: Tod McQuillin: "Re: Poor network performance: a lot of timeouts"
    Date: Mon, 30 May 2005 21:22:47 -0400
    To: Sebastian Ahndorf <webmaster@it-is-warlock.de>
    
    

    At 04:56 PM 5/30/2005, Sebastian Ahndorf wrote:
    >Kris Kennaway wrote:
    >>>Both sides must have same config, autosense should work if there
    >>>is no config possibility in other end.
    >>
    >>autosense may in fact not work, especially on low-quality NICs like rl.
    >
    >I don't agree to that.
    >I had similar problems with my network using a cheap switch with
    >some realtek nics. I had the nics running 100baseTX Full Duplex.
    >Changing this to autosense made the problems gone.
    >
    >Reason (as some people of the german questions-list told me):
    >Many cheap switches always send their autosensepakets, and have
    >great problems if the nics connected to the switch do not response
    >to the autosensepakets (cause they are configured to 10/100baseTX
    >full/half duplex).
    >Also realtek nics are far away from being good nics, they work
    >without problems with the autosensemode and a cheap switch for me
    >(and many other people I know).
    >
    >I would suggest the starter of this thread to use autosense with his
    >nic (if not tested yet).

    The deal is simply this:

    Autosense must be enabled on both sides to autonegotiate speed/duplex.

    If you force one side to full duplex, the other side still autosenses
    (on most unmanaged switches), fail, and will fall back to half duplex
    causing a duplex mismatch. You have to force the other side to full
    duplex as well. If you cannot do this, leave it at auto, or set the
    side you can manage to half so they agree.

    I personally like to leave everything on auto except links between
    switches and between routers and switches which I force to full. It
    always works out well for me on practically any platform or OS. Maybe
    on one or two occasions I've experienced faulty drivers which cause
    the autosensing to not work on the NIC and just default to half duplex.

    Vinny Abello
    Network Engineer
    Server Management
    vinny@tellurian.com
    (973)300-9211 x 125
    (973)940-6125 (Direct)
    PGP Key Fingerprint: 3BC5 9A48 FC78 03D3 82E0 E935 5325 FBCB 0100 977A

    Tellurian Networks - The Ultimate Internet Connection
    http://www.tellurian.com (888)TELLURIAN

    "Courage is resistance to fear, mastery of fear - not absence of
    fear" -- Mark Twain

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  • Next message: Tod McQuillin: "Re: Poor network performance: a lot of timeouts"

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