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Common Interface Settings

Common interface settings include name, type, enabled, description, and custom MAC address. Type-specific settings are covered in the dedicated sections for Bridging, Link Aggregation, Ethernet, IP Addressing, and Routing.

Interface Name

The interface name is limited to 1-15 characters due to Linux kernel constraints. Physical interfaces use their system-assigned names (e.g., eth0, eth1), while user-created interfaces can be named freely within this limit.

Tip

Naming conventions like br0, lag0, vlan10, or eth0.20 allow the CLI to automatically infer the interface type.

Interface Type

The type setting defines what kind of interface this is: bridge, lag, vlan, veth, etc. When configuring via the CLI, the type is often inferred from the interface name. However, when configuring remotely via NETCONF or RESTCONF, the type must be set explicitly.

admin@example:/config/> edit interface br0
admin@example:/config/interface/br0/> set type bridge

Available types can be listed from the CLI:

admin@example:/config/interface/br0/> set type ?
  bridge     IEEE bridge interface.
  dummy      Linux dummy interface.  Useful mostly for testing.
  ethernet   Any Ethernet interfaces, regardless of speed, RFC 3635.
  gre        GRE tunnel interface.
  gretap     GRETAP (Ethernet over GRE) tunnel interface.
  lag        IEEE link aggregate interface.
  loopback   Linux loopback interface.
  other      Other interface, i.e., unknown.
  veth       Linux virtual Ethernet pair.
  vlan       Layer 2 Virtual LAN using 802.1Q.
  vxlan      Virtual eXtensible LAN tunnel interface.
  wifi       WiFi (802.11) interface
  wireguard  WireGuard VPN tunnel interface.

Enable/Disable

An interface can be administratively disabled using the enabled setting. By default, interfaces are enabled (true).

admin@example:/config/> edit interface eth0
admin@example:/config/interface/eth0/> set enabled false
admin@example:/config/interface/eth0/> leave

The operational status can be inspected to see both administrative and actual link state:

admin@example:/> show interfaces
INTERFACE       PROTOCOL   STATE       DATA
eth0            ethernet   DISABLED    02:00:00:00:00:00
eth1            ethernet   UP          02:00:00:00:00:01
...

Description

The description is a free-form text string (max 64 characters) saved as the Linux interface alias (ifalias). Use it to document an interface's purpose or add notes for remote debugging.

admin@example:/config/> edit interface eth0
admin@example:/config/interface/eth0/> set description "Uplink to core switch"
admin@example:/config/interface/eth0/> leave

The description is visible in the operational datastore and in show commands:

admin@example:/> show interface eth0
name                : eth0
description         : Uplink to core switch
index               : 2
...

Custom MAC Address

The custom-phys-address can be used to set an interface's MAC address. This is an extension to the ietf-interfaces YANG model, which defines phys-address as read-only1.

Caution

There is no validation or safety checks performed by the system when using custom-phys-address. In particular the offset variant can be dangerous to use -- pay attention to the meaning of bits in the upper-most octet: local bit, multicast/group, etc.

Fixed custom MAC

Use a fixed custom MAC address when the interface must present a specific, deterministic identity on the network. This option bypasses any chassis-derived logic and applies the configured address verbatim.

admin@example:/config/> edit interface veth0a
admin@example:/config/interface/veth0a/> set custom-phys-address static 00:ab:00:11:22:33

=> 00:ab:00:11:22:33

Chassis MAC

Chassis MAC, sometimes also referred to as base MAC. In these two examples it is 00:53:00:c0:ff:ee.

admin@example:/config/> edit interface veth0a
admin@example:/config/interface/veth0a/> set custom-phys-address chassis

=> 00:53:00:c0:ff:ee

Chassis MAC, with offset

When constructing a derived address it is recommended to set the locally administered bit. Same chassis MAC as before.

admin@example:/config/> edit interface veth0a
admin@example:/config/interface/veth0a/> set custom-phys-address chassis offset 02:00:00:00:00:02

=> 02:53:00:c0:ff:f0

  1. A YANG deviation was previously used to make it possible to set phys-address, but this has been replaced with the more flexible custom-phys-address. ↩