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  1. #1
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    Force full duplex, this how?

    ifcfg-eth0

    ETHTOOL_OPTS="speed 100 duplex full autoneg off"

    then restart the network?

    For some reason i totally forgot.. I'm getting some slow speeds on a Cisco 2900 switch (on the switch).

    -dmesg-
    Code:
    eth0: network connection up using port A
        speed:           100
        autonegotiation: yes
        duplex mode:     half
        flowctrl:        none
        irq moderation:  disabled
        scatter-gather:  enabled
    thx
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  2. #2
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    hmm well that didn't work..

    I did a full reboot dmesg shows the same, any ideas?

    logs say this..

    Code:
    Dec 23 07:56:43 webby ifup: Cannot get current device settings: Operation not supported 
    Dec 23 07:56:43 webby ifup:   not setting speed 
    Dec 23 07:56:43 webby ifup:   not setting duplex 
    Dec 23 07:56:43 webby ifup:   not setting autoneg
    is it the switch?

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    Last edited by Jeremy; 12-23-2005 at 03:00 PM.
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  3. #3
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    Moscow
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    on linux you can use mii-tools as i remember for check what happen with your nic (include his capabilities)
    TK Rustelekom LLC Dedicated server since 2002, RIPE NCC member, LIR

  4. #4
    You can either as someone suggested use mii-tool

    # mii-tool

    No opitions, tells you the status of the link

    # mii-tool eth0 -F 100baseTx-FD

    will force 100Mb Full Duplex .. won't always work though

    # mii-tool eth0 -A 100baseTx

    Will advertise both full and half duplex. If your switch link is locked at half duplex, then you need to make the switch port full duplex as well.

    You can use ethtool from command line too

    # ethtool -s eth0 speed 100 duplex full autoneg off

    or

    # ethtool eth0

    to see the supported options, no need to restart the network when changing the interface via mii-tool or ethtool.

    # mii-tool

    Will tell you where you are at and where you finish up.
    Last edited by DigitalN; 12-23-2005 at 09:59 PM.

  5. #5
    Join Date
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    Location
    Detroit
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    Both ends of the connection need to have the same setting. Set the switch to 100/full first then the machine. most of the time, auto does work well. If your switch is not set to auto right now try that first.
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  6. #6
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    Auto negotiate can cause a lot of problems though. I agree with setting both sides as the above poster stated.
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  7. #7
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    Detroit
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    Quote Originally Posted by pixelized
    Auto negotiate can cause a lot of problems though. I agree with setting both sides as the above poster stated.
    Setting both sides also applies to 'auto'. most of the problems with using auto negotiate that I have seen is one side was not set the same.

    You have a machine set to auto and the switch set to 100/full you may have problems.
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  8. #8
    The problems I have seen setting network connection parameters with mii-tool has been due to a crappy switch, that advertises either half or full duplex.. no autoneg

    In these cases, ethtool saves the day by making your interface not try to autonegotiate. (mii-tool does not work in these cases I find)

    So imho, you really need to look at your switch first, as that is likely the cause of the problem.

  9. #9
    Join Date
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    Hmmm the ports are forced 100mbps/fd.

    i still get the error

    Code:
    Dec 23 07:56:43 webby ifup: Cannot get current device settings: Operation not supported 
    Dec 23 07:56:43 webby ifup:   not setting speed 
    Dec 23 07:56:43 webby ifup:   not setting duplex 
    Dec 23 07:56:43 webby ifup:   not setting autoneg
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  10. #10
    What does

    # mii-tool

    reveal?

    What is your switch set to?

  11. #11
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    Code:
    [root@webby ~]# mii-tool eth0
    SIOCGMIIPHY on 'eth0' failed: Bad address
    also trying doesnt work

    Code:
    [root@webby ~]# mii-tool -F 100baseTx-FD eth0
    SIOCGMIIPHY on 'eth0' failed: Bad address
    NIC - Marvell Technology Group Ltd. 88E8001 Gigabit Ethernet Controller

    my route table looks fine, i can shell in and out of it.
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  12. #12
    Join Date
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    Thank you all for your help so far.

    on the switch the command
    Code:
    show run
    out puts this:

    Code:
     interface FastEthernet0/9
     description LAX09-DM
     duplex full
     speed 100
     switchport access vlan 30
     spanning-tree portfast
    dmesg

    Code:
    eth0: network connection up using port A
     speed:           100
     autonegotiation: yes
     duplex mode:     half
     flowctrl:        none
     irq moderation:  disabled
     scatter-gather:  enabled
    
    -------
    
     divert: allocating divert_blk for eth0
     eth0: Yukon Gigabit Ethernet 10/100/1000Base-T Adapter
     PrefPort:A  RlmtMode:Check Link State
    mii-tool - out puts

    Code:
    [root@webby ~]# mii-tool
    SIOCGMIIPHY on 'eth0' failed: Bad address
    no MII interfaces found
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  13. #13
    Try

    # ethtool -s eth0 speed 100 duplex full autoneg off

    Does that work for you?

    Failing that, I would look at changing the switch port and then the network card interface.

  14. #14
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    Code:
    [root@webby ~]# ethtool -s eth0 speed 100 duplex full autoneg off
    Cannot get current device settings: Operation not supported
      not setting speed
      not setting duplex
      not setting autoneg
    O no...
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  15. #15
    It might be best to try setting your switch to 'autonegotiate' rather than forcing full duplex, then set the interface to 'autonegotiate' too.

    Try another network card if all fails, looks like your card doesn't want to be played around with, maybe a driver issue or just the card won't take the changes.
    I'd try autonegotiate both ends, different switch port, then try another nic card.

  16. #16
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    Location
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    I was thinking this to, Dont know why this is such a pain.

    Thanks for your help.
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