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Chapter 5. Configuring Network Connection Settings
This chapter describes various configurations of the network connection settings and shows how to configure them by using NetworkManager.
5.1. Configuring 802.3 Link Settings
You can configure the 802.3 link settings of an Ethernet connection by modifying the following configuration parameters:
802-3-ethernet.auto-negotiate802-3-ethernet.speed802-3-ethernet.duplex
You can configure the 802.3 link settings to three main modes:
- Ignore link negotiation
- Enforce auto-negotiation activation
- Manually set the
speedandduplexlink settings
Ignoring link negotiation
In this case, NetworkManager ignores link configuration for an ethernet connection, keeping the already configuration on the device.
To ignore link negotiation, set the following parameters:
802-3-ethernet.auto-negotiate = no 802-3-ethernet.speed = 0 802-3-ethernet.duplex = NULL
Important
If the
auto-negotiate parameter is set to no, but the speed and duplex values are not set, that does not mean that auto-negotiation is disabled.
Enforcing auto-negotiation activation
In this case, NetworkManager enforces auto-negotiation on a device.
To enforce auto-negotiation activation, set the following options:
802-3-ethernet.auto-negotiate = yes 802-3-ethernet.speed = 0 802-3-ethernet.duplex = NULL
Manually setting the link speed and duplex
In this case, you can manually configure the
speed and duplex settings on the link.
To manually set the
speed and duplex link settings, set the aforementioned parameters as follows:
802-3-ethernet.auto-negotiate = no 802-3-ethernet.speed = [speed in Mbit/s] 802-3-ethernet.duplex = [half |full]
Important
Make sure to set both the
speed and the duplex values, otherwise NetworkManager does not update the link configuration.
As a system administrator, you can configure 802.3 link settings using one of the following options:
- the nmcli tool
- the nm-connection-editor utility
Configuring 802.3 Link Settings with the nmcli Tool
Procedure
- Create a new ethernet connection for the eth0 device.
- Set the 802.3 link setting to a configuration of your choice. For details, see Section 5.1, “Configuring 802.3 Link Settings”For example, to manually set the
speedoption 100 Mbit/s andduplexto full:nmcli connection add con-name MyEthernet type ethernet ifname eth0 \ 802-3-ethernet.auto-negotiate no \ 802-3-ethernet.speed 100 \ 802-3-ethernet.duplex full
Configuring 802.3 Link Settings with nm-connection-editor
Procedure
- Enter nm-connection-editor in a terminal.
- Select the ethernet connection you want to edit and click the gear wheel icon to move to the editing dialog. See Section 3.4.3, “Common Configuration Options Using nm-connection-editor” for more information.
- Select the link negotiation of your choice.
Ignore: link configuration is skipped (default).Automatic: link auto-negotiation is enforced on the device.Manual: theSpeedandDuplexoptions can be specified to enforce the link negotiation.
Figure 5.1. Configure 802.3 link settings using nm-connection-editor
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