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Wireless Networks Thread, Excessive CRC/Alignment Errors in Technical; I've got 22 HP dc7800, 4 being used by admin connected to a Procurve 2450 and the rest connected to ...
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    Excessive CRC/Alignment Errors

    I've got 22 HP dc7800, 4 being used by admin connected to a Procurve 2450 and the rest connected to a Procurve 5406zl.

    I'm getting lots of Excessive CRC/Alignment Errors and the switchs are also reporting lots of packet errors. The machines seem to be connecting without any issues.

    Cabling is mostly new, we don't seem to have similar issues with other equipment attached to the same cabling.

    Any ideas?

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    ajs
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    I've been having similar issues in a few rooms for over a year and a half now. Performance across the network isn't affected and as a result it has become one of the very low priority jobs to look at.

    One or two errors have gone away as I've replaced seemingly unrelated cables but the odd error still appears from time to time.

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    Try manually setting the switch port and the network card to 100M/b full duplex as quite often these are casued by negotiation problems. You could also try updating nic drivers (try the ones off Intel rather than HP if you are on the latest HP drivers).
    It can also be interference on the cable run which some network cards cope with better than others, but you need someone with a posh Fluke tester to find that.
    As others have said, unless this is causing network issues its not really worth bothering about.

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    Quote Originally Posted by teejay View Post
    Try manually setting the switch port and the network card to 100M/b full duplex as quite often these are casued by negotiation problems.
    Tried forcing them both to gigabit and 100mb. I've tried the latest HP drivers, but giving the generic Intel ones a go is something I'll try.

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    Quote Originally Posted by K.C.Leblanc View Post
    Tried forcing them both to gigabit and 100mb. I've tried the latest HP drivers, but giving the generic Intel ones a go is something I'll try.
    These types of error are usually caused by bad termination in the cables, faulty NICs or cable length has exceeded the recommedede for cat5e and cat 6 its 100m so make sure that from one end to another it is not more than 100m. Also if its fibre then i would check the fibre modules (transcievers) as these can also go bad and you see this type of issues.

    Try the following:

    - Check the duplex and speed of the link
    - change the cables i.e. patch leads
    - change the fibre patch leads and the module if its possible.
    - Change the switch port and plug the patch lead into another port to eliminate faulty port on the switch
    - If you have any testers then meaure the length of the cable

    Also make sure that you clear the counters on the switches or at least note down the current counters for CRC errors, Alignment errors etc so you can compare after swapping the cables etc.

    Its a process of elimination i'm afraid.

    HTH,

    Ash.

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    Quote Originally Posted by ashok View Post
    These types of error are usually caused by bad termination in the cables, faulty NICs or cable length has exceeded the recommedede for cat5e and cat 6 its 100m

    Ash.
    I'm very much doubting faulty nics, because it's occurring on 20 odd new machines. The termination is a nagging concern, most of these machines are on new cabling that was installed over the summer, I've done a bit of testing with a dumb tester. Anyone know if it's possible to hire network testing kit.

    Total length isn't going to be an issue, the runs arn't even 25 meters.

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    SYNACK's Avatar
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    I would check how far they have untwisted the internal cores of the cables at each end where they have wired them in. They should have untwisted as little as possible as it is the twisting that sheilds it from interfearence. If it is untwisted too far the live cores will act like little arials happily broadcasting rubbish that is most likely to be picked up by an 'arial' of a simmilar size in close proximity - like in a cabinet or wall socket.

    If this is the case they will happily sit transmitting rubbish to each other untill they are reterminated with minimal untwisting.

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