NIC Auto-Negotiation and Duplex Settings - NIC satus

FAQ: How to change Duplex and/or Auto-Negotiation NIC settings in Linux?

Date: November 20, 2008. Categories: debian, faq, fedora, howtos, linux, tips and ubuntu

Q: How to disable auto-negotiation option of my network interface card and set up half/full duplex mode manually from Linux command line (CLI)? By the way, how to see current settings?
A: There are several Linux utilities coming with almost any distribution including Debian, Ubuntu, Fedora, RedHat, Mandriva, Centos whatever. See details below.

auto-nego

ethtool

This is rather powerful utility can display and change settings of ethernet network interface card. You can easily disable/enable autonegotiation option for your NIC, also it’s possible to manually set up duplex mode, configure wake-on-lan options, set speed settings. Just look through full manual page for ethtool. Here are several ethtool usage examples:

ethtool eth0 - shows current NIC settings

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: 10Mb/s
     Duplex: Half
     Port: MII
     PHYAD: 32
     Transceiver: internal
     Auto-negotiation: off
     Supports Wake-on: pumbg
     Wake-on: d
     Current message level: 0x00000007 (7)
     Link detected: yes

ethtool -s eth0 duplex half autoneg off - disables auto-negotiation, enables Half Duplex.
ethtool -s eth1 duplex full speed 1000 autoneg off - disables auto-negotiation, enables Falf Duplex and sets up Speed to 1000 Mb/s.

mii-tool

According to manual it allows to manipulate and see media-independent interface status. Let’s see examples:

bash-3.1# mii-tool eth0
eth0: negotiated 100baseTx-FD, link ok - shows 100 Mbps speed, Full Duplex, Auto-negotiation is on.
bash-3.1# mii-tool eth0 -F 10baseT-HD - enables 10 Mb/s Half Duplex connection.

Taken From: http://www.linuxscrew.com/2008/11/20/faq-how-to-change-duplex-andor-auto-negotiation-nic-settings-in-linux/

Listing Partitions and Disks with FDISK

## List All Partions and Disks #####

In order to list all partions and disks using fdisk, while root just type:

# fdisk -l

And you will get disks and partitions informations all together:

Disk /dev/sda: 32.2 GB, 32212254720 bytes
255 heads, 63 sectors/track, 3916 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 3916 31455206 fb Unknown

Disk /dev/sdb: 53.6 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/cciss/c0d0: 73.3 GB, 73372631040 bytes
255 heads, 63 sectors/track, 8920 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/cciss/c0d0p1 * 1 13 104391 83 Linux
/dev/cciss/c0d0p2 14 650 5116702+ 83 Linux
/dev/cciss/c0d0p3 651 8584 63729855 fb Unknown
/dev/cciss/c0d0p4 8585 8920 2698920 f Win95 Ext'd (LBA)
/dev/cciss/c0d0p5 8585 8653 554211 82 Linux swap
/dev/cciss/c0d0p6 8654 8907 2040223+ 83 Linux
/dev/cciss/c0d0p7 8908 8920 104391 fc Unknown

This is quite confusing if you have multiple disks with multiple partitions, so next I'm, going to show you how to, only show the disks and then, pick a disk and then list it`s partitions



## List All Disks #####

Now I'm going to show you how to list only the disks, for that while in root just type:

# fdisk -l | grep Disk

The result shold be something like this:

Disk /dev/sdk doesn't contain a valid partition table
Disk /dev/sda: 32.2 GB, 32212254720 bytes
Disk /dev/sdb: 53.6 GB, 53687091200 bytes
Disk /dev/cciss/c0d0: 73.3 GB, 73372631040 bytes

Here you only see the harddrives and no partitions, now you can pick which hardrive you want to see the partitions. Im picking /dev/cciss/c0d0, and next i will show you only it's partitions.


## List a Disk's Partitions #####

Now listing all the partitions in one disk, for that while in root just type:

# fdisk -l /dev/cciss/c0d0

The result should be something like this:

Disk /dev/cciss/c0d0: 73.3 GB, 73372631040 bytes
255 heads, 63 sectors/track, 8920 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/cciss/c0d0p1 * 1 13 104391 83 Linux
/dev/cciss/c0d0p2 14 650 5116702+ 83 Linux
/dev/cciss/c0d0p3 651 8584 63729855 fb Unknown
/dev/cciss/c0d0p4 8585 8920 2698920 f Win95 Ext'd (LBA)
/dev/cciss/c0d0p5 8585 8653 554211 82 Linux swap
/dev/cciss/c0d0p6 8654 8907 2040223+ 83 Linux
/dev/cciss/c0d0p7 8908 8920 104391 fc Unknown


That's all, happy listing...