Signals that comprise digital data are sent onto a network by various devices. Data is sent as packets, encapsulated at each layer of the network model according to the OSI (Open Systems Interconnection) model. This conceptual model defines seven layers, with Layer 1 being the physical layer (the actual hardware components of the network) and Layer 7 being the application layer (the software applications that use the network).
Devices that operate at different layers of the OSI model perform different functions in sending data onto a network. For example, a computer’s Ethernet interface card sends data using TCP/IP at Layer 4. In contrast, an SNMP (Simple Network Management Protocol) agent uses UDP at Layer 4 to send management information to a network management station.
What is a Network Interface Card (NIC)?
A network interface card (NIC) is a computer hardware device that connects a computer to a computer network. NICs may be used for both wired and wireless connections.
The NIC serves as a physical interface between the computer and the network. A NIC typically has its dedicated processor, memory, firmware, and driver that work together to move data across the network. A NIC may also be referred to as a network or LAN adapter.
NICs are found in almost all devices connected to a network, including PCs, laptops, servers, routers, switches, and storage systems. They are also found in many embedded devices such as printers, scanners, and cameras. Most NICs support multiple types of networking protocols such as Ethernet, Fiber Distributed Data Interface (FDDI), token ring, and Asynchronous Transfer Mode (ATM).
How Does a NIC Work?
A NIC handles all requests and data to/from a computer on behalf of the computer’s software. When you connect to a network, your NIC is responsible for making the physical connection to the network.
NICs are designed according to a specific standard that dictates what kinds of signals they can send and receive and how they send and receive them. The best-known networking standard is the Open Systems Interconnection model (OSI). The OSI model divides networking into seven layers, each with specific responsibilities.
Types of NICs
Several different NICs are available today, each designed for different purposes. The most common type is the Ethernet NIC, which connects computers to an Ethernet network. Ethernet NICs can be divided into home and office use and server use. Home and office use Ethernet NICs are typically 10/100 Mbps, while server uses Ethernet NICs are usually 10/100/1000 Mbps or higher.
Other types of NICs include Token Ring NICs, which are used to connect computers to a Token Ring network; Asynchronous Transfer Mode (ATM) NICs, which are used to connect computers to an ATM network; Fiber Distributed Data Interface (FDDI) NICs, which are used to connect computers to an FDDI network; and Wireless LAN (WLAN) NICs, which are used connecting computers to a wireless LAN.
What is an Ethernet Cable?
In computer networking, an Ethernet cable is a popular network cable used to connect devices on a Local Area Network (LAN). It is commonly used in homes and offices to connect computers, routers, modems, and other devices. Different Ethernet cables are available, but the most common is the Cat 5 cable.
Ethernet cables are made up of four pairs of twisted wires. Each pair is responsible for carrying a different signal. The first two pairs (pins 1 & 2, and 3 & 6) are used for sending data, while the second two pairs (pins 4, 5, 7 & 8) are used for receiving data. The wires are typically made from copper, but fiber optic cables are also available.
Ethernet cables are classified according to the maximum speed they can support. The most common classification is Cat 5, which can support speeds up to 100 Mbps ( Megabits per second). There are also faster versions available, such as Cat 5e and Cat 6, which can support speeds up to 1000 Mbps.
What is a Modem?
Modems are one of the least understood but most important components of modern computer networks. A modem is a device that modulates an analog carrier signal to encode digital information and demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data.
Modems can be used with any means of transmitting analog signals, from light-emitting diodes (LEDs) to radio waves. A common type of modem is one that turns the digital data of a computer into modulated electrical signals for transmission over telephone lines and demodulated by another modem at the receiver side to recover the digital data.
Computer networks using the Internet Protocol (IP) standard require all communication between devices with assigned IP addresses. For two devices on different networks to communicate, they must use a router as an intermediary. Routers direct traffic by translating IP addresses into physical locations.
All modems include a receive (Rx) and a transmit (Tx) unit, which transmit data in both directions: upstream from receptors such as computers or cameras and downstream toward end users like TVs or monitors.
What is a Router?
A router is a network device that forwards packets between networks. Routers connect two or more logical subnets, which do not necessarily map one-to-one to the router’s physical interface. A single router may have multiple physical interfaces (for example, WiFi and Ethernet), each of which belongs to a different subnet. When a packet arrives at the router, the router determines which physical interface the packet should be sent to based on the packet’s destination IP address and the routing table.
Routers operate at layer 3 of the OSI model. A typical home network contains two or more subnets: one for each device connected to the router (e.g., computer, printer, etc.). The router has an interface for each subnet and routes packets between them based on the destination IP address.
Routers typically also support dynamic routing protocols such as RIP, OSPF, or BGP to discover patients automatically and update their routing tables accordingly. Many routers also support SNMP for monitoring and management purposes.
In conclusion, the device that sends signals from a computer onto a network is referred to as a network interface. This device can be anything from a simple cable or modem to a more complex device such as a router or switch. The network interface is responsible for mediating the communication between the computer and the network.