How to Change NIC speed without restarting the Linux AS 3 server?????

Posted on 2007-10-12
Medium Priority
Last Modified: 2013-12-16
I would like to change the NIC settings from 100 to 1000, Auto_negotiation Yes without restarting the  Linux Machine. Please see the details below

# uname -r
# cat /etc/redhat-release
Red Hat Enterprise Linux AS release 3 (Taroon Update 6)
#ethtool eth0
Settings for eth0:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  Not reported
        Advertised auto-negotiation: No
        Speed: 100Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: off
        Supports Wake-on: g
        Wake-on: d
        Link detected: yes
# cat /etc/modules.conf
alias eth0 bcm5700
options eth0 line_speed=100 auto_speed=0 full_duplex=1
alias eth1 bcm5700
options eth1 line_speed=100 auto_speed=0 full_duplex=1
alias scsi_hostadapter cciss
alias usb-controller usb-ohci
options bond0 miimon=100 mode=active-backup
alias bond0 bonding
Question by:bennisabraham
  • 3
LVL 30

Expert Comment

by:Kerem ERSOY
ID: 20065932

You can use ethtool command for modifying speed:
ethtool -s eth0 speed 100 duplex full autoneg on

The resuls are immediate you don't need to reboot. But for the next boot you can either remove:
options eth0 line_speed=100 auto_speed=0 full_duplex=1
options eth1 line_speed=100 auto_speed=0 full_duplex=1

Lines from your /etc/modules conf thiswill force your adapter to autonegotiation od change the "line_speed=100" to "line_speed=1000" if you want to do it manually.

LVL 30

Accepted Solution

Kerem ERSOY earned 2000 total points
ID: 20066016
sorry I mean:
ethtool -s eth0 speed 1000 duplex full autoneg on

In the previous post I mestakenly told "speed 100".

The best way is to remove optinos statements from your /etc/modules.conf.
You might as well use this command :

ethtool -s eth0 autoneg on

This will negotiate he best speed your switch supports automatically. Here are the options for ethtool set command:

ethtool -s DEVNAME \
                [ speed 10|100|1000 ] \
                [ duplex half|full ]    \
                [ port tp|aui|bnc|mii|fibre ] \
                [ autoneg on|off ] \
                [ phyad %d ] \
                [ xcvr internal|external ] \
                [ wol p|u|m|b|a|g|s|d... ] \
                [ sopass %x:%x:%x:%x:%x:%x ] \
                [ msglvl %d ]


Author Comment

ID: 20100925
How would i set as Auto Auto for this server
LVL 30

Expert Comment

by:Kerem ERSOY
ID: 20102410
You want to set it back to auto ??

Then you'd issue:
ethtool -s eth0 autoneg on

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