Network interface bandwidth setting

Does anyone know how to change the network interface setting in Linux?
<---------100Mbps------------>
PC1 <------->Switched Hub<------->PC2

For instance, I would like to change the link (PC1 to PC2) from 100Mbps
downto 1Mbps.

Thanks,
Ben B

change tcp buffer size on both machine and this will lower the bandwidth
(bandwith=RTT*buffer_size)
"Ben B" <benjamin.bappu@bt.com> a écrit dans le message de
news:bspnfs$kld$1@visp.bt.co.uk...
> Does anyone know how to change the network interface setting in Linux?
> <---------100Mbps------------>
> PC1 <------->Switched Hub<------->PC2
>
> For instance, I would like to change the link (PC1 to PC2) from 100Mbps
> downto 1Mbps.
>
> Thanks,
> Ben B
>
>

I got it working with this:
tc qdisc add dev eth0 root tbf rate 1Mbit buffer 200kB limit 100kB

Cheers,
Ben B

"Yves Cognet" <yves_cognet@imedia-tech.com> wrote in message
news:bsu7e9$vjr$1@news-reader4.wanadoo.fr...
> change tcp buffer size on both machine and this will lower the bandwidth
> (bandwith=RTT*buffer_size)
> "Ben B" <benjamin.bappu@bt.com> a écrit dans le message de
> news:bspnfs$kld$1@visp.bt.co.uk...
> > Does anyone know how to change the network interface setting in Linux?
> > <---------100Mbps------------>
> > PC1 <------->Switched Hub<------->PC2
> >
> > For instance, I would like to change the link (PC1 to PC2) from 100Mbps
> > downto 1Mbps.
> >
> > Thanks,
> > Ben B
> >
> >
>
>

Ben B wrote:
> Does anyone know how to change the network interface setting in Linux?
> <---------100Mbps------------>
> PC1 <------->Switched Hub<------->PC2
>
> For instance, I would like to change the link (PC1 to PC2) from 100Mbps
> downto 1Mbps.

You can't.
Fast Ethernet has two link speeds, normal (10mbit) and fast (100mbit).

You can easily force the segment to run on 10mbit by forcing one
interface to 10mbit and setting the other to auto (default), but to slow
it down any more you'll have to apply bandwidth throttling.

No, I'm not contradicting myself - your question was "I want to change
the *link* speed" - which you can't.

Limiting the bandwidth is certainly possible, see Ben's reply.

I'm none too sure about the advisability of lowering the tcp buffer
size, since this may well have adverse side-effects.

Why not simply use "mii-tool"?
# /sbin/mii-tool eth0 -F 10baseTx-HD
If he wants to set it for full duplex, then change the HD to FD.
Likewise, "ethtool" will do the same for more recent versions.
Hope that helps.
KJ


Jeroen Geilman <jeroen@nospam.net> wrote in message news:<3ff4dee3$0$325$e4fe514c@news.xs4all.nl>...
> Ben B wrote:
> > Does anyone know how to change the network interface setting in Linux?
> > <---------100Mbps------------>
> > PC1 <------->Switched Hub<------->PC2
> >
> > For instance, I would like to change the link (PC1 to PC2) from 100Mbps
> > downto 1Mbps.
>
> You can't.
> Fast Ethernet has two link speeds, normal (10mbit) and fast (100mbit).
>
> You can easily force the segment to run on 10mbit by forcing one
> interface to 10mbit and setting the other to auto (default), but to slow
> it down any more you'll have to apply bandwidth throttling.
>
> No, I'm not contradicting myself - your question was "I want to change
> the *link* speed" - which you can't.
>
> Limiting the bandwidth is certainly possible, see Ben's reply.
>
> I'm none too sure about the advisability of lowering the tcp buffer
> size, since this may well have adverse side-effects.

This is excatly what I was looking for!!!

Cheers,
Ben B

"Kerry Cox" <kerry.cox@ksl.com> wrote in message
news:4b080d14.0401021025.2dbf3b43@posting.google.c om...
> Why not simply use "mii-tool"?
> # /sbin/mii-tool eth0 -F 10baseTx-HD
> If he wants to set it for full duplex, then change the HD to FD.
> Likewise, "ethtool" will do the same for more recent versions.
> Hope that helps.
> KJ
>
>
> Jeroen Geilman <jeroen@nospam.net> wrote in message
news:<3ff4dee3$0$325$e4fe514c@news.xs4all.nl>...
> > Ben B wrote:
> > > Does anyone know how to change the network interface setting in Linux?
> > > <---------100Mbps------------>
> > > PC1 <------->Switched Hub<------->PC2
> > >
> > > For instance, I would like to change the link (PC1 to PC2) from
100Mbps
> > > downto 1Mbps.
> >
> > You can't.
> > Fast Ethernet has two link speeds, normal (10mbit) and fast (100mbit).
> >
> > You can easily force the segment to run on 10mbit by forcing one
> > interface to 10mbit and setting the other to auto (default), but to slow
> > it down any more you'll have to apply bandwidth throttling.
> >
> > No, I'm not contradicting myself - your question was "I want to change
> > the *link* speed" - which you can't.
> >
> > Limiting the bandwidth is certainly possible, see Ben's reply.
> >
> > I'm none too sure about the advisability of lowering the tcp buffer
> > size, since this may well have adverse side-effects.