What is an interface; what is the difference between a physical (ETH) interface and a virtual interface?

Short answer

An interface is the point where the device connects to a network; IP addresses and routes are defined on interfaces. In TR7, physical interfaces are of the ETH type: they are located in the hardware of the device or on the virtual card provided by the virtualization platform, and they cannot be added or deleted from the TR7 user interface; in the Edit Interface form, their name and type cannot be changed, while their route table, Details settings (e.g. MTU) and, in a cluster, VIP settings are edited. Virtual interfaces, on the other hand, are created on ETHs (or on one another) with the Add Interface form and can be deleted: VLAN, VXLAN, V-ETH, V-ETH(Peer), Bond, LACP and Bridge. Virtual interfaces are used to divide a connection into networks with tags (VLAN), to carry L2 over L3 (VXLAN), to combine ports (Bond, LACP), to connect interfaces to the same L2 segment (Bridge), to open a sub-interface with an independent MAC (V-ETH) or to connect route tables to one another (V-ETH(Peer)) (Interface types and use cases).

Where It Is Used in TR7

Where	Field / label	What for
Network → Interfaces	Interfaces List: Type column, status indicator, IP and route rows	Listing the interfaces, adding IPs and routes
Network → Interfaces → Actions → Add Interface	Type (ETH is disabled in the list)	Creating a virtual interface
Network → Interfaces → Edit Interface	Edit Interface form; on ETH, Interface name is read-only	Changing the interface settings
Settings → Device Management → Hardware Management	Hardware Management table (Name, MAC address, Usage…)	Physical interface inventory; Sync interface selection for the cluster
Left Monitor Panel → Interfaces	Interfaces tab; when a row is clicked, the Dashboard screen of the interface opens	Monitoring the interfaces with status and traffic metrics
WEB-CLI	network interface add, network interface list (network interface); sys-cmd ip show address (ip show address)	Managing the interface definitions; seeing the interfaces in the system and their addresses

Interface Types

Type	What it is for	Built on
ETH	Physical interface or the interface provided by the virtualization platform	Hardware; not added, not deleted
VLAN	Logical network separated with an 802.1Q tag (What is a VLAN; what is a VLAN interface for in TR7?)	ETH, Bond, LACP
VXLAN	Carrying an L2 segment over L3 with UDP (What is VXLAN; how does it differ from VLAN?)	ETH, VLAN, Bond, LACP
V-ETH	Virtual interface with an independent MAC address on a parent interface	ETH, VLAN, Bond, LACP
V-ETH(Peer)	Two-ended virtual cable; the ends can be in different route tables	Independent (as a pair)
Bond, LACP	Combining more than one ETH in a single logical interface (What is the difference between Bond and LACP?)	ETH members
Bridge	Connecting interfaces to the same L2 segment (What is a bridge interface; why is STP important?)	Interfaces in the same route table

Common Misconceptions

• "An ETH interface can be deleted and recreated." ETH comes from the hardware; a delete attempt is rejected with Cannot delete physical interface. Only virtual interfaces are deleted.
• "A virtual interface works like a separate physical connection." VLAN, V-ETH and VXLAN traffic flows over the physical connection of the interface beneath it; if that connection is lost, the virtual interface is also affected.
• "The type of an interface can be changed later." Type is read-only in the edit form; for a different type, a new interface is created.

How it is done in the documentation

• Interfaces List · Supported Interface Types
• Add Interface · Interface Types and Use Cases
• Edit Interface · What Is Edit Interface?
• Hardware Management

Related questions

• What is the difference between the Up, No Link and Down states of an interface?
• What is a VLAN; what is a VLAN interface for in TR7?
• What is the difference between Bond and LACP?
• What is the Left Monitor Panel; which objects does it let me monitor?