Network Interface

What Is a Network Interface?[1]

A network interface is the point of interconnection between a computer and a private or public network. A network interface is generally a network interface card (NIC) but does not have to have a physical form. Instead, the network interface can be implemented in software. For example, the loopback interface ( for IPv4 and::1 for IPv6) is not a physical device but a piece of software simulating a network interface. The loopback interface is commonly used in test environments.

The network interface may refer to:

  • Network interface controller, a computer hardware component that connects a computer to a computer network
  • Network interface device, a device that serves as the demarcation point between a telephone carrier's local loop and the customer's wiring
  • Virtual network interface, an abstract virtualized representation of a computer network interface
  • Loopback interface, a virtual network interface that connects a host to itself

A network interface may be associated with a physical device, or it may be a representation of a virtual interface. The “loopback” device, which is a virtual interface available in most Linux environments to connect back to the same machine, is an example of this.

  • LAN: LAN stands for “local area network”. It refers to a network or a portion of a network that is not publicly accessible to the greater internet. A home or office network is an example of a LAN.
  • WAN: WAN stands for “wide area network”. It means a network that is much more extensive than a LAN. While WAN is the relevant term to use to describe large, dispersed networks in general, it is usually meant to mean the internet, as a whole.

If an interface is said to be connected to the WAN, it is generally assumed that it is reachable through the internet.

TCP/IP Network Interfaces[2]

The TCP/IP Network Interface layer formats IP datagrams at the Network layer into packets that specific network technologies can understand and transmit.

A network interface is a network-specific software that communicates with the network-specific device driver and the IP layer in order to provide the IP layer with a consistent interface to all network adapters that might be present.

The IP layer selects the appropriate network interface based on the destination address of the packet to be transmitted. Each network interface has a network address. The Network Interface layer is responsible for adding or removing any link layer protocol header required to deliver a message to its destination. The network adapter device driver controls the network adapter card.

Although not required, a network interface is usually associated with a network adapter. For instance, the loopback interface has no network adapter associated with it. A machine must have one network adapter card for each network (not network type) to which it connects. However, a machine requires only one copy of the network interface software for each network adapter it uses. For instance, if a host attaches to two token-ring networks, it must have two network adapter cards. However, only one copy of the token-ring network interface software and one copy of the token-ring device driver is required.

TCP/IP supports types of network interfaces:

  • Standard Ethernet Version 2 (en)
  • IEEE 802.3 (et)
  • Token-ring (tr)
  • Serial Line Internet Protocol (SLIP)
  • Loopback (lo)
  • FDDI
  • Serial Optical (so)
  • Point-to-Point Protocol (PPP)
  • Virtual IP Address (vi)

Network Interface Types[3]

The Linux system distinguishes two types of network interfaces:

  • Physical network interface: A physical network interface represents a network hardware device such as NIC (Network Interface Card), WNIC (Wireless Network Interface Card), or a modem.
  • Virtual network interface: A virtual network interface does not represent a hardware device but is linked to a network device. It can be associated with a physical or virtual interface.

Components of Network Interface Cards[4]

Network interface card components include the following:

  • Speed. All NICs have a speed rating in terms of Mbps which suggests the general performance of the card when implemented in a computer network with ample bandwidth. If the bandwidth is lower than the NIC or multiple computers are connected with the same controller, the labeled speed will be slowed down. The average Ethernet NICs come in 10 Mbps, 100 Mbps, 1000 Mbps, and 1 Gbps varieties.
  • Driver. This is the required software that passes data between the computer's operating system (OS) and the NIC. When a NIC is installed on a computer, the corresponding driver software is also downloaded. Drivers must stay updated and uncorrupted to ensure optimal performance from the NIC.
  • MAC address. Unique, unchangeable MAC addresses, also known as physical network addresses, are assigned to NICs. These are used to deliver Ethernet packets to the computer.
  • Connectivity LED. Most NICs have an LED indicator integrated into the connector to notify the user of when the network is connected and data is being transmitted.
  • Router. A router is also sometimes needed to enable communication between a computer and other devices. In this case, the NIC connects to the router which is connected to the internet.

Network Interface Porting[5]

A network interface port is the physical docking spot where any external appliance can have a connection to the computer. Along with the physical port, this might be a programmatic docking spot where the data passage happens from program to computer across the Internet.

To know what type of protocol receiving traffic it must be directed to, various port numbers are utilized. They permit only a single host over one IP address to operate a networking service. Every port number provides different services and for every host, there are 65535 ports. This porting is all regulated by IANA.

VLANs and interfacing groups include virtual ports. The interfacing groups consider various physical ports as one port, whereas VLANs divide physical ports into many logical types of ports.

VLAN is the logical type of port that accepts and transmits VLAN-tagged traffic. The features consist of a VLAN ID for the port. The fundamental interface grouping port is termed a VLAN trunk port and the associated switch ports need to be configured to trunk VLAN IDs.

So, computer networking interfaces support a wide range of applications and services like WWW, digital types of audio and video, printers, email and direct messaging, fax equipment, application shared use and accumulation servers, and many more.

See Also

TCP/IP (Transmission Control Protocol/Internet Protocol)