How to change eth0 from Gigabit to 100 MBit? - Ubuntu

This is a discussion on How to change eth0 from Gigabit to 100 MBit? - Ubuntu ; I have a machine that always was on a 100 MB port, but was gigabit capable. Recently networking was upgraded and now it is on a full gigabit switch. I do NOT want it to have a gigabit capacity, since ...

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Thread: How to change eth0 from Gigabit to 100 MBit?

  1. How to change eth0 from Gigabit to 100 MBit?

    I have a machine that always was on a 100 MB port, but was gigabit
    capable. Recently networking was upgraded and now it is on a full
    gigabit switch.

    I do NOT want it to have a gigabit capacity, since it could overwhelm
    a certain WAN network line that this machine shares with others. So I
    want to set it to 100 MBit.

    I tried

    ethtool -s eth0 speed 100

    but it did not change anything (though network connectivity was off
    for a second or two).

    How can I change the max speed?

    --
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  2. Re: How to change eth0 from Gigabit to 100 MBit?

    Ignoramus7289 wrote:
    > I have a machine that always was on a 100 MB port, but was gigabit
    > capable. Recently networking was upgraded and now it is on a full
    > gigabit switch.
    >
    > I do NOT want it to have a gigabit capacity, since it could overwhelm
    > a certain WAN network line that this machine shares with others. So I
    > want to set it to 100 MBit.
    >
    > I tried
    >
    > ethtool -s eth0 speed 100
    >
    > but it did not change anything (though network connectivity was off
    > for a second or two).
    >
    > How can I change the max speed?
    >
    > --
    > Due to extreme spam originating from Google Groups, and their inattention
    > to spammers, I and many others block all articles originating
    > from Google Groups. If you want your postings to be seen by
    > more readers you will need to find a different means of
    > posting on Usenet.
    > http://improve-usenet.org/


    Look at this hypocrite: He wants to improve the usenet and
    then violates the netiquette with that oversized and rude
    sig.



    What you want to do is simple, jerk. And I hope no one tells
    you.


    Sid


    --
    contact: http://tinyurl.com/5jxzoj

  3. Re: How to change eth0 from Gigabit to 100 MBit?

    Ignoramus7289 wrote:
    > I have a machine that always was on a 100 MB port, but was gigabit
    > capable. Recently networking was upgraded and now it is on a full
    > gigabit switch.
    >
    > I do NOT want it to have a gigabit capacity, since it could overwhelm
    > a certain WAN network line that this machine shares with others. So I
    > want to set it to 100 MBit.
    >
    > I tried
    >
    > ethtool -s eth0 speed 100
    >
    > but it did not change anything (though network connectivity was off
    > for a second or two).
    >
    > How can I change the max speed?
    >

    Look here

    http://www.cyberciti.biz/tips/howto-...permanent.html

    It SHOULD work, if it doesn't, you my have a driver issue.

    >


  4. Re: How to change eth0 from Gigabit to 100 MBit?

    Sidney Lambe writes:

    > Look at this hypocrite: He wants to improve the usenet and
    > then violates the netiquette with that oversized and rude
    > sig.


    Now THAT'S the Alan Connor I remember. Okay - I'm convinced.

  5. Re: How to change eth0 from Gigabit to 100 MBit?

    On Sun, 19 Oct 2008 22:10:37 -0500, Ignoramus7289 wrote:

    > I have a machine that always was on a 100 MB port, but was gigabit
    > capable. Recently networking was upgraded and now it is on a full
    > gigabit switch.
    >
    > I do NOT want it to have a gigabit capacity, since it could overwhelm a
    > certain WAN network line that this machine shares with others. So I want
    > to set it to 100 MBit.
    >
    > I tried
    >
    > ethtool -s eth0 speed 100
    >
    > but it did not change anything (though network connectivity was off for
    > a second or two).
    >
    > How can I change the max speed?


    I don't know if this would work but you could try

    ifconfig eth0 down media 100baseT

    this is just a guess on my part based on reading the man page for
    ifconfig. But given that ethtool didn't work it's possible that your
    ethernet interface can be controlled in this manner.

    What you really want to do is to set the priorities on your switch or
    router ports. You can't do that on the type of cheap switches that
    consumers use, you can on managed switches that are used in enterprise
    networks.

  6. Re: How to change eth0 from Gigabit to 100 MBit?

    On Mon, 20 Oct 2008 07:38:35 -0500, General Schvantzkopf wrote:

    > On Sun, 19 Oct 2008 22:10:37 -0500, Ignoramus7289 wrote:
    >
    >> I have a machine that always was on a 100 MB port, but was gigabit
    >> capable. Recently networking was upgraded and now it is on a full
    >> gigabit switch.
    >>
    >> I do NOT want it to have a gigabit capacity, since it could overwhelm a
    >> certain WAN network line that this machine shares with others. So I
    >> want to set it to 100 MBit.
    >>
    >> I tried
    >>
    >> ethtool -s eth0 speed 100
    >>
    >> but it did not change anything (though network connectivity was off for
    >> a second or two).
    >>
    >> How can I change the max speed?

    >
    > I don't know if this would work but you could try
    >
    > ifconfig eth0 down media 100baseT
    >
    > this is just a guess on my part based on reading the man page for
    > ifconfig. But given that ethtool didn't work it's possible that your
    > ethernet interface can be controlled in this manner.


    I meant can't not can. Sorry.


  7. Re: How to change eth0 from Gigabit to 100 MBit?

    General, thanks. this works:

    ethtool -s eth0 speed 100 duplex half autoneg off

    --
    Due to extreme spam originating from Google Groups, and their inattention
    to spammers, I and many others block all articles originating
    from Google Groups. If you want your postings to be seen by
    more readers you will need to find a different means of
    posting on Usenet.
    http://improve-usenet.org/

  8. Re: How to change eth0 from Gigabit to 100 MBit?

    Ignoramus28797 wrote:
    > General, thanks. this works:
    >
    > ethtool -s eth0 speed 100 duplex half autoneg off
    >

    I'd go duplex full though. 'autoneg off' is probably the key thing in
    tis case.


  9. Re: How to change eth0 from Gigabit to 100 MBit?

    On 2008-10-20, The Natural Philosopher wrote:
    > Ignoramus28797 wrote:
    >> General, thanks. this works:
    >>
    >> ethtool -s eth0 speed 100 duplex half autoneg off
    >>

    > I'd go duplex full though. 'autoneg off' is probably the key thing in
    > tis case.
    >


    full duplex worked extremely poorly.

    --
    Due to extreme spam originating from Google Groups, and their inattention
    to spammers, I and many others block all articles originating
    from Google Groups. If you want your postings to be seen by
    more readers you will need to find a different means of
    posting on Usenet.
    http://improve-usenet.org/

  10. Re: How to change eth0 from Gigabit to 100 MBit?

    Hello,

    Ignoramus28797 a écrit :
    >>>
    >>> ethtool -s eth0 speed 100 duplex half autoneg off
    >>>

    >> I'd go duplex full though. 'autoneg off' is probably the key thing in
    >> tis case.

    >
    > full duplex worked extremely poorly.


    Probably because disabling autonegotiation disabled full duplex at the
    other end.

  11. Re: How to change eth0 from Gigabit to 100 MBit?

    On 2008-10-20, General Schvantzkopf wrote:
    > On Mon, 20 Oct 2008 15:20:51 +0100, The Natural Philosopher wrote:
    >
    >> Ignoramus28797 wrote:
    >>> General, thanks. this works:
    >>>
    >>> ethtool -s eth0 speed 100 duplex half autoneg off
    >>>

    >> I'd go duplex full though. 'autoneg off' is probably the key thing in
    >> tis case.

    >
    > I don't see how any of this will help solve the problem of one system
    > dominating the WAN connection. Unless the OP lives in Japan his broadband
    > connection is much less than 100Mb, in the US a cable modem does 8-16M


    This is not a private home, it is an enterprise and the WAN link is 600
    Mbps.

    > (the higher speeds you see when you run one of the speed tests are a
    > mirage caused by the Powerboost feature on Comcast which boosts the first
    > 20MBytes, download an ISO to see what your real speed is). If the system
    > is generating 1 bit/second more than the link can handle it will saturate
    > the connection. As I mentioned earlier, enterprise switches have the
    > capability of managing traffic. However if the OP owned something like
    > that he wouldn't have asked a question about setting the speed of the
    > ethernet connection down.
    >
    > I have a question for the OP, is this just a theoretical concern or are
    > you running some particular program that's eating all of your WAN
    > bandwidth?


    The latter.

    > If it's a specific application then the best place to deal with
    > the problem is in the application itself. If you can't do anything about
    > it then the next best solution is probably to set the size of your TCP
    > windows down so that the offending machine will throttle it's TCP
    > connections.


    I think that for now, being on 100 mbps will work well.

    --
    Due to extreme spam originating from Google Groups, and their inattention
    to spammers, I and many others block all articles originating
    from Google Groups. If you want your postings to be seen by
    more readers you will need to find a different means of
    posting on Usenet.
    http://improve-usenet.org/

  12. Re: How to change eth0 from Gigabit to 100 MBit?

    Ignoramus28797 wrote:
    > On 2008-10-20, The Natural Philosopher wrote:
    >> Ignoramus28797 wrote:
    >>> General, thanks. this works:
    >>>
    >>> ethtool -s eth0 speed 100 duplex half autoneg off
    >>>

    >> I'd go duplex full though. 'autoneg off' is probably the key thing in
    >> tis case.
    >>

    >
    > full duplex worked extremely poorly.
    >

    Did it? Oh well, if you have found the magic bullet..just use it!

    Life's too short...

  13. Re: How to change eth0 from Gigabit to 100 MBit?

    Ignoramus28797 wrote:
    > On 2008-10-20, General Schvantzkopf wrote:
    >> On Mon, 20 Oct 2008 15:20:51 +0100, The Natural Philosopher wrote:
    >>
    >>> Ignoramus28797 wrote:
    >>>> General, thanks. this works:
    >>>>
    >>>> ethtool -s eth0 speed 100 duplex half autoneg off
    >>>>
    >>> I'd go duplex full though. 'autoneg off' is probably the key thing in
    >>> tis case.

    >> I don't see how any of this will help solve the problem of one system
    >> dominating the WAN connection. Unless the OP lives in Japan his broadband
    >> connection is much less than 100Mb, in the US a cable modem does 8-16M

    >
    > This is not a private home, it is an enterprise and the WAN link is 600
    > Mbps.
    >
    >> (the higher speeds you see when you run one of the speed tests are a
    >> mirage caused by the Powerboost feature on Comcast which boosts the first
    >> 20MBytes, download an ISO to see what your real speed is). If the system
    >> is generating 1 bit/second more than the link can handle it will saturate
    >> the connection. As I mentioned earlier, enterprise switches have the
    >> capability of managing traffic. However if the OP owned something like
    >> that he wouldn't have asked a question about setting the speed of the
    >> ethernet connection down.
    >>
    >> I have a question for the OP, is this just a theoretical concern or are
    >> you running some particular program that's eating all of your WAN
    >> bandwidth?

    >
    > The latter.
    >
    >> If it's a specific application then the best place to deal with
    >> the problem is in the application itself. If you can't do anything about
    >> it then the next best solution is probably to set the size of your TCP
    >> windows down so that the offending machine will throttle it's TCP
    >> connections.

    >
    > I think that for now, being on 100 mbps will work well.
    >

    I think so too. you cant throttle bandwidth of one app using window
    sizing. At best it shares what is around more evenly and smoothly.

    If you have a decent router interfacing to the network ,you should be
    able to do traffic shaping based on port or IP numbers though.

    But for a quick fix, you have probably got the right answer.


  14. Re: How to change eth0 from Gigabit to 100 MBit?

    Ignoramus7289 writes:

    >I have a machine that always was on a 100 MB port, but was gigabit
    >capable. Recently networking was upgraded and now it is on a full
    >gigabit switch.


    >I do NOT want it to have a gigabit capacity, since it could overwhelm
    >a certain WAN network line that this machine shares with others. So I
    >want to set it to 100 MBit.


    I have no idea what "it would overwhelm a certain WAN network line" means.
    That WAN line will operate at its usual speed. It will not get overwhelmed.
    If it gets too much data, it will simply tell the data to wait ( slowing
    down the GB line if necessary). Your fears are unfounded.

    Remember that your provider probably has a GB line coming in for a long
    time. Did that ovewhelm you when you were on 100MB?



    >I tried


    > ethtool -s eth0 speed 100


    >but it did not change anything (though network connectivity was off
    >for a second or two).


    >How can I change the max speed?


    Think again why you want to change it.

  15. Re: How to change eth0 from Gigabit to 100 MBit?


    I guess the OP doesn't have much faith in TCP congestion control and
    avoidance algorithms? That or in combinations of tc and netem to
    limit bandwidth to destinations?

    > >> I'd go duplex full though. 'autoneg off' is probably the key
    > >> thing in tis case.

    > > full duplex worked extremely poorly.

    > Probably because disabling autonegotiation disabled full duplex at
    > the other end.


    Some ancient boilerplate I can trot-out from time to time:

    How 100Base-T Autoneg is supposed to work:

    When both sides of the link are set to autoneg, they will "negotiate"
    the duplex setting and select full-duplex if both sides can do
    full-duplex.

    If one side is hardcoded and not using autoneg, the autoneg process
    will "fail" and the side trying to autoneg is required by spec to use
    half-duplex mode.

    If one side is using half-duplex, and the other is using full-duplex,
    sorrow and woe is the usual result.

    So, the following table shows what will happen given various settings
    on each side:

    Auto Half Full

    Auto Happiness Lucky Sorrow

    Half Lucky Happiness Sorrow

    Full Sorrow Sorrow Happiness

    Happiness means that there is a good shot of everything going well.
    Lucky means that things will likely go well, but not because you did
    anything correctly Sorrow means that there _will_ be a duplex
    mis-match.

    When there is a duplex mismatch, on the side running half-duplex you
    will see various errors and probably a number of _LATE_ collisions
    ("normal" collisions don't count here). On the side running
    full-duplex you will see things like FCS errors. Note that those
    errors are not necessarily conclusive, they are simply indicators.

    Further, it is important to keep in mind that a "clean" ping (or the
    like - eg "linkloop" or default netperf TCP_RR) test result is
    inconclusive here - a duplex mismatch causes lost traffic _only_ when
    both sides of the link try to speak at the same time. A typical ping
    test, being synchronous, one at a time request/response, never tries
    to have both sides talking at the same time.

    Finally, when/if you migrate to 1000Base-T, everything has to be set
    to auto-neg anyway.

    rick jones
    --
    firebug n, the idiot who tosses a lit cigarette out his car window
    these opinions are mine, all mine; HP might not want them anyway...
    feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

  16. Re: How to change eth0 from Gigabit to 100 MBit?

    On 2008-10-20, Rick Jones wrote:
    >
    > I guess the OP doesn't have much faith in TCP congestion control and
    > avoidance algorithms?


    I have an idea about that, however, there is data going through that
    line that is high priority that I do not want to compete with, too
    much.

    > That or in combinations of tc and netem to limit bandwidth to
    > destinations?


    I had no idea about those, looks nifty.

    >> >> I'd go duplex full though. 'autoneg off' is probably the key
    >> >> thing in tis case.
    >> > full duplex worked extremely poorly.

    >> Probably because disabling autonegotiation disabled full duplex at
    >> the other end.

    >
    > Some ancient boilerplate I can trot-out from time to time:
    >
    > How 100Base-T Autoneg is supposed to work:
    >
    > When both sides of the link are set to autoneg, they will "negotiate"
    > the duplex setting and select full-duplex if both sides can do
    > full-duplex.
    >
    > If one side is hardcoded and not using autoneg, the autoneg process
    > will "fail" and the side trying to autoneg is required by spec to use
    > half-duplex mode.
    >
    > If one side is using half-duplex, and the other is using full-duplex,
    > sorrow and woe is the usual result.
    >
    > So, the following table shows what will happen given various settings
    > on each side:
    >
    > Auto Half Full
    >
    > Auto Happiness Lucky Sorrow
    >
    > Half Lucky Happiness Sorrow
    >
    > Full Sorrow Sorrow Happiness
    >
    > Happiness means that there is a good shot of everything going well.
    > Lucky means that things will likely go well, but not because you did
    > anything correctly Sorrow means that there _will_ be a duplex
    > mis-match.
    >
    > When there is a duplex mismatch, on the side running half-duplex you
    > will see various errors and probably a number of _LATE_ collisions
    > ("normal" collisions don't count here). On the side running
    > full-duplex you will see things like FCS errors. Note that those
    > errors are not necessarily conclusive, they are simply indicators.
    >
    > Further, it is important to keep in mind that a "clean" ping (or the
    > like - eg "linkloop" or default netperf TCP_RR) test result is
    > inconclusive here - a duplex mismatch causes lost traffic _only_ when
    > both sides of the link try to speak at the same time. A typical ping
    > test, being synchronous, one at a time request/response, never tries
    > to have both sides talking at the same time.
    >
    > Finally, when/if you migrate to 1000Base-T, everything has to be set
    > to auto-neg anyway.


    Rick, I found that half duplex 100 megabit works great for me. Thanks
    for a great article.

    --
    Due to extreme spam originating from Google Groups, and their inattention
    to spammers, I and many others block all articles originating
    from Google Groups. If you want your postings to be seen by
    more readers you will need to find a different means of
    posting on Usenet.
    http://improve-usenet.org/

  17. Re: How to change eth0 from Gigabit to 100 MBit?

    Stephan Rose wrote:
    > On Mon, 20 Oct 2008 11:59:23 -0700, Sidney Lambe wrote:
    >
    >
    >> So you want to improve the usenet, but not only post oversized and rude
    >> netiquette-violating sigs, but change you name to avoid people's
    >> killfiles at the drop of a hat, forcing people who don't want to. to see
    >> your posts to see them.
    >>
    >> And you crosspost without including a followup.
    >>
    >> Better googlegroupers than usenet vermin like you.
    >>
    >> again.
    >>
    >> I'll bet I've already killfiled dozens of names you hide behind.
    >>
    >> This is good. Keeps the garbage out of my downloads.
    >>
    >>
    >> Sid

    >
    > You bitch and moan about him having a couple extra lines in his sig but
    > you have absolutely no problem posting an 18 line rant with nearly 100
    > lines quoted text that contribute absolutely NOTHING!
    >
    > You are the only hypocrite here.
    >
    > --
    > Stephan
    > 1986 Pontiac Fiero GT
    >
    > 君の事思い出す日なんてないのは
    > 君の事忘れたときがないから



    I'd bet a lot that you are ignoramus[0-9]*, ad infinitum.

    What the hell are you doing here?

    You post most often on microsoft.public.windows.vista.general:

    http://groups.google.com/groups?q=au...2008&safe=off&

    And you've never posted here before:

    http://groups.google.com/groups?as_q...=2008&safe=off


    Thanks for proving my point. And giving me another addition to
    my killfile that will help keep the **** out of my downloads.

    Sid


    --
    contact: http://tinyurl.com/5jxzoj
    googlegroups users see:
    http://tinyurl.com/5mbs7c

  18. Re: How to change eth0 from Gigabit to 100 MBit?

    Ignoramus7289 :
    > I have a machine that always was on a 100 MB port, but was gigabit
    > capable. Recently networking was upgraded and now it is on a full
    > gigabit switch.
    >
    > I do NOT want it to have a gigabit capacity, since it could overwhelm
    > a certain WAN network line that this machine shares with others. So I
    > want to set it to 100 MBit.
    >
    > I tried
    >
    > ethtool -s eth0 speed 100
    >
    > but it did not change anything (though network connectivity was off
    > for a second or two).
    >
    > How can I change the max speed?


    A surefire foolproof way would be to use a cable (make it yourself) that
    only has wires connected on pins 1,2,3, and 6. Control at the hardware
    level doesn't get bugs .

    Well, fewer...

    --
    SEIZE LIBERTY

    www.websterscafe.com

  19. Re: How to change eth0 from Gigabit to 100 MBit?


    Let me look at my Alan Connor Troll Detection Checklist.

    Sidney Lambe writes:

    > I'd bet a lot that you are ignoramus[0-9]*, ad infinitum.


    Accusation of sock puppets. Check.

    > You post most often on microsoft.public.windows.vista.general:


    Looking into the google groups profile. Check.

    > Thanks for proving my point. And giving me another addition to
    > my killfile that will help keep the **** out of my downloads.


    Public announcement of killfile entry. Check.

    That's Alan Connors!!! I guess you FINALLY were forced to admit your
    Challenge/respose anti-spam "mail" system sucks.

    And rather than eat crow, you changed your name.....


  20. Re: How to change eth0 from Gigabit to 100 MBit?

    ["Followup-To:" header set to comp.os.linux.misc.]
    Maxwell Lol wrote:
    > Sidney Lambe writes:
    >
    >> Look at this hypocrite: He wants to improve the usenet and
    >> then violates the netiquette with that oversized and rude
    >> sig.

    >
    > Now THAT'S the Alan Connor I remember. Okay - I'm convinced.


    http://groups.google.com/groups?q=au...2008&safe=off&

    Why do all these stupid and dishonest losers with a 1000 names
    apiece want to believe I'm some bogeyman from the usenet's past?
    Why do they think that I or anyone else cares about the subject
    or what people with zero credibility think?

    "Maxwell Lol" wasn't even posting on the usenet when that character
    was around. Not even close. He's only got 1450 posts.

    I've been on the usenet longer than he has.

    Or rather, longer than this troll has been using the name "Maxwell Lol".

    If only my enemies in the real world were as incompetent and
    pathetic as this fellow.

    So Dan C, how's it going? You ever going to get a life?

    When are you going to learn that I don't care what you think or
    post?

    Nobody does. If you had any credibility you wouldn't have to change
    your name like a whore changes her panties.

    Do you realize that this makes over 80 of your aliases I've killfiled?

    Sid

    --
    contact: http://tinyurl.com/5jxzoj
    googlegroups users see:
    http://tinyurl.com/5mbs7c

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