Interfaces in NetBox represent network interfaces used to exchange data with connected devices. On modern networks, these are most commonly Ethernet, but other types are supported as well. IP addresses and VLANs can be assigned to interfaces.
Like most device components, interfaces are instantiated automatically from [interface templates](./interfacetemplate.md) assigned to the selected device type when a device is created.
Although both devices and virtual machines both can have interfaces assigned, a separate model is used for each. Thus, device interfaces have some properties that are not present on virtual machine interfaces and vice versa.
The interface type refers to the physical termination or port on the device. Interfaces which employ a removable optic or similar transceiver should be defined to represent the type of transceiver in use, irrespective of the physical termination to that transceiver.
### Speed
The operating speed, in kilobits per second (kbps).
### Duplex
The operation duplex (full, half, or auto).
### VRF
The [virtual routing and forwarding](../ipam/vrf.md) instance to which this interface is assigned.
The [MAC address](./macaddress.md) assigned to this interface which is designated as its primary.
!!! note "Changed in NetBox v4.2"
The MAC address of an interface (formerly a concrete database field) is available as a property, `mac_address`, which reflects the value of the primary linked [MAC address](./macaddress.md) object.
The 64-bit world-wide name (for Fibre Channel interfaces).
### MTU
The interface's configured maximum transmissible unit (MTU).
### Transmit Power
The interface's configured output power, in dBm (for optical interfaces).
### Enabled
If not selected, this interface will be treated as disabled/inoperative.
### Management Only
Designates the interface as handling management traffic only (e.g. for out-of-band management connections).
### Mark Connected
If selected, this component will be treated as if a cable has been connected.
### Parent Interface
Virtual interfaces can be bound to a physical parent interface. This is helpful for modeling virtual interfaces which employ encapsulation on a physical interface, such as an 802.1Q VLAN-tagged subinterface.
Interfaces can be bridged to other interfaces on a device in two manners: symmetric or grouped.
* **Symmetric:** For example, eth0 is bridged to eth1, and eth1 is bridged to eth0. This effects a point-to-point bridge between the two interfaces, which NetBox will follow when tracing cable paths.
* **Grouped:** Multiple interfaces are each bridged to a common virtual bridge interface, effecting a multiaccess bridged segment. NetBox cannot follow these relationships when tracing cable paths, because no forwarding information is available.
### LAG Interface
Physical interfaces may be arranged into link aggregation groups (LAGs, also known as "trunks") and associated with a parent LAG (virtual) interface. LAG interfaces can be recursively nested to model bonding of trunk groups. Like all virtual interfaces, LAG interfaces cannot be connected physically.
### PoE Mode
The power over Ethernet (PoE) mode for this interface. (This field must be left empty for interfaces which do not support PoE.) Choices include:
* Powered device (PD)
* Power-supplying equipment (PSE)
### PoE Type
The classification of PoE transmission supported, for PoE-enabled interfaces. This can be one of the listed IEEE 802.3 standards, or a passive setting (24 or 48 volts across two or four pairs).
### 802.1Q Mode
For switched Ethernet interfaces, this identifies the 802.1Q encapsulation strategy in effect. Options include:
* **Access:** All traffic is assigned to a single VLAN, with no tagging.
* **Tagged:** One untagged "native" VLAN is allowed, as well as any number of tagged VLANs.
* **Tagged (all):** Implies that all VLANs are carried by the interface. One untagged VLAN may be designated.
The configured operation frequency of a wireless interface, in MHz. This is typically inferred by the configured channel above, but may be set manually e.g. to identify a licensed channel not available for general use.
The configured channel width of a wireless interface, in MHz. This is typically inferred by the configured channel above, but may be set manually e.g. to identify a licensed channel not available for general use.
