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Author Topic: 3com ethernet - how to set 10Mbps  (Read 2754 times)

Offline sathish

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3com ethernet - how to set 10Mbps
« on: November 04, 2005, 07:54:37 PM »
Hello Linux team!!!

Have installed RedHat9.0 and done masquerading... having 3Com Ethernet cards, I want this cards to set for 10Mbps, how to do in command mode??

Plz let me know.

Thanks in advance.


Offline vlinux1

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Setting Duplex mode of Nic
« Reply #1 on: November 05, 2005, 10:18:27 AM »

Please read this it will help u to set the duplex mode of Nic.

Changing NIC Speed and Duplex

There is no better Linux investment than the purchase of a fully Linux compatible NIC card. Most Linux vendors will have a list of compatible hardware on their Web sites: read this carefully before you start hooking up you machine to the network. If you can't find any of the desired models in your local computer store, then a model in the same family or series should be sufficient. Most cards will work, but only the fully compatible ones will provide you with error-free, consistent throughput.

Linux defaults to automatically negotiating the speed and duplex of it's NIC automatically with that of the switch to which it is attached. Configuring a switch port to auto-negotiate the speed and duplex often isn't sufficient because there are frequently differences in the implementation of the protocol standard.

Typically, NICs with failed negotiation will work, but this is usually accompanied by many collision type errors being seen on the NIC when using the ifconfig -a command and only marginal performance. Don't limit your troubleshooting of these types of errors to just failed negotiation; the problem could also be due to a bad NIC card, switch port, or cabling.
Using mii-tool

One of the original Linux tools for setting the speed and duplex of your NIC card was the mii-tool command. It is destined to be deprecated and replaced by the newer ethtool command, but many older NICs support only mii-tool so you'll need to be aware of it.

Issuing the command without any arguments gives a brief status report, as seen in the next example, with unsupported NICs providing an Operation not supported message. NICs that are not compatible with mii-tool often will still work, but you have to refer to the manufacturer's guides to set the speed and duplex to anything but auto-negotiate.


[root@bigboy tmp]# mii-tool

SIOCGMIIPHY on 'eth0' failed: Operation not supported

eth1: 100 Mbit, half duplex, link ok

[root@bigboy tmp]#


By using the verbose mode -v switch you can get much more information. In this case, negotiation was OK, with the NIC selecting 100Mbps, full duplex mode (FD):


[root@bigboy tmp]# mii-tool -v

eth1: negotiated 100baseTx-FD, link ok

  product info: vendor 00:10:18, model 33 rev 2

  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

  link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control

[root@bigboy tmp]#

Setting Your NIC's Speed Parameters with mii-tool

You can set your NIC to force itself to a particular speed and duplex by using the -F switch with any of the following options: 100baseTx-FD, 100baseTx-HD, 10baseT-FD, or 10baseT-HD. Remember that you could lose all network connectivity to your server if you force your NIC to a particular speed/duplex that doesn't match that of your switch:


[root@bigboy tmp]# mii-tool -F 100baseTx-FD eth0


Unfortunately there is no way to set this on reboot permanently except by placing it the command in the /etc/rc.local file to let it be run at the very end of the booting process or by creating your own startup script if you need it set earlier. Creating your own startup scripts is covered in Chapter 7.
Using ethtool

The ethtool command is slated to be the replacement for mii-tool in the near future and tends to be supported by newer NIC cards.

The command provides the status of the interface you provide as its argument. Here we see interface eth0 not doing autonegotiation and set to a speed of 100 Mbps, full duplex. A list of supported modes is also provided at the top of the output.


[root@bigboy tmp]# ethtool eth0

Settings for eth0:

        Supported ports: [ TP MII ]

        Supported link modes:   10baseT/Half 10baseT/Full

                                100baseT/Half 100baseT/Full

        Supports auto-negotiation: Yes

        Advertised link modes:  10baseT/Half 10baseT/Full

                                100baseT/Half 100baseT/Full

        Advertised auto-negotiation: No

        Speed: 100Mb/s

        Duplex: Full

        Port: MII

        PHYAD: 1

        Transceiver: internal

        Auto-negotiation: off

        Supports Wake-on: g

        Wake-on: g

        Current message level: 0x00000007 (7)

        Link detected: yes

[root@bigboy tmp]#

Setting Your NIC's Speed Parameters with ethtool

Unlike mii-tool, ethtool settings can be permanently set as part of the interface's configuration script with the ETHTOOL_OPTS variable. In our next example, the settings will be set to 100 Mbps, full duplex with no chance for auto-negotiation on the next reboot:



# File: /etc/sysconfig/network-script/ifcfg-eth0




ETHTOOL_OPTS="speed 100 duplex full autoneg off"


You can test the application of these parameters by shutting down the interface and activating it again with the ifup and ifdown commands.

These settings can also be changed from the command line using the -s switch followed by the interface name and its desired configuration parameters.


[root@bigboy tmp]# ethtool -s eth1 speed 100 duplex full autoneg off

[root@bigboy tmp]#


The Linux man pages give more details on other ethtool options, but you can get a quick guide by just entering the ethtool command alone, which provides a quicker summary.


[root@bigboy tmp]# ethtool



        ethtool -s DEVNAME \

                [ speed 10|100|1000 ] \

                [ duplex half|full ]    \

                [ port tp|aui|bnc|mii|fibre ] \



[root@bigboy tmp]#