[plug] gigabit lan

William Kenworthy billk at iinet.net.au
Tue Jan 8 19:27:13 WST 2008


Try mii-tool if it supports your NIC (most are supported).  It will tell
you what the card (on linux) is set to.

Things that go wrong:
set to half rather than full duplex - very common
missmatch between duplex settings (switch and NIC - see logs for odd
messages)
some switches (cisco comes to mind here) often guess wrong on settings
PCI bus/software maxed out - you are already getting the max the
hardware/software can do
The way you are measuring it is giving deceptive readings

for one of my machines, connected to a 100M cisco switch:
lshw shows:
        *-network
             description: Ethernet interface
             product: 88E8001 Gigabit Ethernet Controller
             vendor: Marvell Technology Group Ltd.
             physical id: a
             bus info: pci at 0000:00:0a.0
             logical name: eth0
             version: 13
             serial: 00:13:d4:be:52:70
             size: 100MB/s
             capacity: 1GB/s
             width: 32 bits
             clock: 66MHz
             capabilities: pm vpd bus_master cap_list ethernet physical
tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
             configuration: autonegotiation=on broadcast=yes driver=skge
driverversion=1.11 duplex=full firmware=N/A ip=192.168.1.14 latency=64
link=yes maxlatency=31 mingnt=23 module=skge multicast=yes port=twisted
pair speed=100MB/s

so its 1Gbits, BUT

myth1 ~ # mii-tool -vv 
eth0: negotiated 100baseTx-FD flow-control, link ok
  registers for MII PHY 0: 
    1000 796d 0141 0c25 0de1 45e1 0005 2001
    0000 0300 4000 0000 0000 0000 0000 3000
    0068 6d0c c480 0000 0170 0000 0000 0000
    4105 0008 000a 848f 0000 0000 0000 0000
  product info: vendor 00:50:43, model 2 rev 5
  basic mode:   autonegotiation enabled
  basic status: autonegotiation complete, link ok
  capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
  advertising:  100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
flow-control
  link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
flow-control

Doesnt show it as gigabit capable, not that it matters here :)
could be driver?

BillK


On Tue, 2008-01-08 at 18:21 +0900, Adrian Chadd wrote:
> The first thing to do is grab iperf and read up about it.
> You can then test the network speeds between hosts by running iperf
> and seeing if you can get >100mbit.
> 
> If you can get >100mbit from iperf but can't get more than 3.6mbytes/sec
> (so 36mbit/sec) then you're low on CPU or disk IO. Probably disk IO.
> 
> If you can't get >100mbit from iperf then either you have strangely slow
> CPUs or something else is messed up.
> 
> The trick to debugging these issues is to come up with ways of isolating
> particular components - or eliminating others - to test. In this case
> you want to isolate the obvious bottleneck in a fileserver - disk IO and
> CPU - from just blitting raw bits over a network interface.
> 
> Also, those onboard network interfaces sound crappy, cheap and slow. :)
> You should get closer to 300mbit out of them though (excluding disk
> bottlenecks) !
> 
> 
> 
> 
> Adrian
> 
> On Tue, Jan 08, 2008, Kev wrote:
> > G'day all
> > 
> > I've just replaced 2 x 10/100 8 port switches (daisy chained) in our 
> > home p2p network with 1 x 16 port gigabit switch.  Most (but not all) of 
> > our home machines have gb nics on motherboard, including the 2 right 
> > here on my desk.  One has a Marvell 88E8001 Gigabit Ethernet Controller 
> > with the skge driver installed and the other has an Nvidia CK8S Ethernet 
> > Controller with the forcedeth driver installed.  These are the default 
> > drivers installed by Xandros.
> > 
> > I use only Samba on the network because there is a mix of Windoze and 
> > Linux machines at home and thus far (the last 3(ish) years) Samba has 
> > run flawlessly.  Even now Samba seems to be running OK.
> > 
> > The problem:  There appears to be no improvement in network speeds - no 
> > change at all.  Copying files between these 2 machines I have in front 
> > of me happens at about 3.6Mbytes/sec according to gkrellm.  I'm using 
> > good condition bought, moulded cat5E cables, each 2m long.  Only the 
> > switch between them.
> > 
> > A complicating factor is that I'm really NOT very technically adept, 
> > particularly with Linux and particularly with networking issues.
> > 
> > Perhaps someone out there might be able to ask me the right questions to 
> > elicit the information required to help me speed things along a little.
> > 
> > 
> > Tia
> > Kev
> > 
> > -- 
> > =======================================================================
> > Kev Downes
> > kdownes at tpg.com.au  ph 0404 7 0808 2
> > We used to use and recommend Xandros but they went to the dark side
> > So we'll soon be using and recommending Debian Etch
> > =======================================================================
> > There are 10 types of people ...
> >   ... those who understand binary, and those who don't!
> > =======================================================================
> > They say a marble sized object collided with some gasses, and had
> > a massive explosion and the universe was born.
> >   - to believe this takes more faith than I have.
> > =======================================================================
> > 
> > _______________________________________________
> > PLUG discussion list: plug at plug.org.au
> > http://www.plug.org.au/mailman/listinfo/plug
> > Committee e-mail: committee at plug.linux.org.au
> 
-- 
William Kenworthy <billk at iinet.net.au>
Home in Perth!



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