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Ignoramus7289
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 Posted: Mon Oct 20, 2008 7:56 am Post subject: How to change eth0 from Gigabit to 100 MBit? |
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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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Sidney Lambe
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| Posted: Mon Oct 20, 2008 7:56 am Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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Ignoramus7289 <ignoramus7289@NOSPAM.7289.invalid> wrote:
| Quote: | 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.
<plonk>
What you want to do is simple, jerk. And I hope no one tells
you.
Sid
--
contact: http://tinyurl.com/5jxzoj |
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The Natural Philosopher
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| Posted: Mon Oct 20, 2008 7:56 am Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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Ignoramus7289 wrote:
| Quote: | 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-linux-add-ethtool-duplex-settings-permanent.html
It SHOULD work, if it doesn't, you my have a driver issue.
> |
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Maxwell Lol
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| Posted: Mon Oct 20, 2008 4:32 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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Sidney Lambe <nospam@nospam.invalid> writes:
| Quote: | 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. |
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General Schvantzkopf
Guest
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| Posted: Mon Oct 20, 2008 5:38 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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On Sun, 19 Oct 2008 22:10:37 -0500, Ignoramus7289 wrote:
| Quote: | 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. |
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Rick Jones
Guest
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| Posted: Mon Oct 20, 2008 6:26 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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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?
| Quote: | 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... |
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General Schvantzkopf
Guest
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| Posted: Mon Oct 20, 2008 6:55 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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On Mon, 20 Oct 2008 07:38:35 -0500, General Schvantzkopf wrote:
| Quote: | 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.
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I meant can't not can. Sorry. |
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Ignoramus28797
Guest
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| Posted: Mon Oct 20, 2008 6:59 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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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/ |
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The Natural Philosopher
Guest
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| Posted: Mon Oct 20, 2008 7:20 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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Ignoramus28797 wrote:
| Quote: | 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. |
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Ignoramus28797
Guest
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| Posted: Mon Oct 20, 2008 7:42 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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On 2008-10-20, The Natural Philosopher <a@b.c> wrote:
| Quote: | 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/ |
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Pascal Hambourg
Guest
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| Posted: Mon Oct 20, 2008 7:46 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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Hello,
Ignoramus28797 a écrit :
| Quote: |
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. |
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General Schvantzkopf
Guest
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| Posted: Mon Oct 20, 2008 7:50 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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On Mon, 20 Oct 2008 15:20:51 +0100, The Natural Philosopher wrote:
| Quote: | 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
(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? 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. |
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Ignoramus28797
Guest
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| Posted: Mon Oct 20, 2008 7:52 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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On 2008-10-20, General Schvantzkopf <schvantzkopf@yahoo.com> wrote:
| Quote: | 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.
| Quote: | (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.
| Quote: | 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/ |
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The Natural Philosopher
Guest
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| Posted: Mon Oct 20, 2008 8:11 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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Ignoramus28797 wrote:
| Quote: | On 2008-10-20, The Natural Philosopher <a@b.c> 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... |
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The Natural Philosopher
Guest
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| Posted: Mon Oct 20, 2008 8:15 pm Post subject: Re: How to change eth0 from Gigabit to 100 MBit? |
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Ignoramus28797 wrote:
| Quote: | On 2008-10-20, General Schvantzkopf <schvantzkopf@yahoo.com> 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. |
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