A report on Physical layer

RTL8201 Ethernet PHY chip
Texas Instruments DP83825 - 3mm x 3mm 3.3V PHY chip
Micrel KS8721CL - 3.3V Single Power Supply 10/100BASE-TX/FX MII Physical Layer Transceiver

First and lowest layer; The layer most closely associated with the physical connection between devices.

- Physical layer
RTL8201 Ethernet PHY chip

31 related topics with Alpha

Overall

Communication in the OSI-Model (example with layers 3 to 5)

OSI model

8 links

Conceptual model that describes the universal standard of communication functions of a telecommunication system or computing system, without any regard to the system's underlying internal technology and specific protocol suites.

Conceptual model that describes the universal standard of communication functions of a telecommunication system or computing system, without any regard to the system's underlying internal technology and specific protocol suites.

Communication in the OSI-Model (example with layers 3 to 5)

The Physical Layer is responsible for the transmission and reception of unstructured raw data between a device, such as a network interface controller, Ethernet hub, or network switch, and a physical transmission medium.

Data link layer

6 links

Second layer of the seven-layer OSI model of computer networking.

Second layer of the seven-layer OSI model of computer networking.

This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer.

Network Packet

Computer network

6 links

Set of computers sharing resources located on or provided by network nodes.

Set of computers sharing resources located on or provided by network nodes.

Network Packet
Common network topologies
A sample overlay network
Network links
Fiber optic cables are used to transmit light from one computer/network node to another
2007 map showing submarine optical fiber telecommunication cables around the world.
Computers are very often connected to networks using wireless links
An ATM network interface in the form of an accessory card. A lot of network interfaces are built-in.
A typical home or small office router showing the ADSL telephone line and Ethernet network cable connections
Firewalls
The TCP/IP model and its relation to common protocols used at different layers of the model.
Message flows between two devices (A-B) at the four layers of the TCP/IP model in the presence of a router (R). Red flows are effective communication paths, black paths are across the actual network links.
SONET & SDH
Asynchronous Transfer Mode
Routing calculates good paths through a network for information to take. For example, from node 1 to node 6 the best routes are likely to be 1-8-7-6, 1-8-10-6 or 1-9-10-6, as these are the shortest routes.
Partial map of the Internet, based on the January 15, 2005 data found on opte.org . Each line is drawn between two nodes, representing two IP addresses. The length of the lines is indicative of the delay between those two nodes. This graph represents less than 30% of the Class C networks reachable.

Bus network: all nodes are connected to a common medium along this medium. This was the layout used in the original Ethernet, called 10BASE5 and 10BASE2. This is still a common topology on the data link layer, although modern physical layer variants use point-to-point links instead, forming a star or a tree.

Diagram of the first internetworked connection

Internet protocol suite

4 links

Set of communication protocols used in the Internet and similar computer networks.

Set of communication protocols used in the Internet and similar computer networks.

Diagram of the first internetworked connection
An SRI International Packet Radio Van, used for the first three-way internetworked transmission.
Conceptual data flow in a simple network topology of two hosts (A and B) connected by a link between their respective routers. The application on each host executes read and write operations as if the processes were directly connected to each other by some kind of data pipe. After establishment of this pipe, most details of the communication are hidden from each process, as the underlying principles of communication are implemented in the lower protocol layers. In analogy, at the transport layer the communication appears as host-to-host, without knowledge of the application data structures and the connecting routers, while at the internetworking layer, individual network boundaries are traversed at each router.
Encapsulation of application data descending through the layers described in RFC 1122

These perform functions, such as framing, to prepare the Internet layer packets for transmission, and finally transmit the frames to the physical layer and over a transmission medium.

Diagram of different network topologies.

Network topology

3 links

Arrangement of the elements of a communication network.

Arrangement of the elements of a communication network.

Diagram of different network topologies.
Fiber optic cables are used to transmit light from one computer/network node to another
2007 map showing submarine optical fiber telecommunication cables around the world.
Personal computers are very often connected to networks using wireless links
An ATM network interface in the form of an accessory card. A lot of network interfaces are built-in.
A typical home or small office router showing the ADSL telephone line and Ethernet network cable connections
Bus network topology
Star network topology
Ring network topology
Fully connected mesh topology
Partially connected mesh topology

A network’s physical topology is a particular concern of the physical layer of the OSI model.

8P8C modular plug pin positioning

Ethernet over twisted pair

4 links

8P8C modular plug pin positioning
Cat 6A cable with an M12X connector in one end and a modular connector in the other.
Comparison of twisted-pair-based Ethernet technologies

Ethernet over twisted-pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network.

Link layer

4 links

Lowest layer in the Internet protocol suite, the networking architecture of the Internet.

Lowest layer in the Internet protocol suite, the networking architecture of the Internet.

Despite the different semantics of layering between the Internet protocol suite and OSI model, the link layer is sometimes described as a combination of the OSI's data link layer (layer 2) and physical layer (layer 1).

A 1990s Ethernet network interface controller card that connects to the motherboard via the now-obsolete ISA bus. This combination card features both a BNC connector (left) for use in (now obsolete) 10BASE2 networks and an 8P8C connector (right) for use in 10BASE-T networks.

Network interface controller

3 links

Computer hardware component that connects a computer to a computer network.

Computer hardware component that connects a computer to a computer network.

A 1990s Ethernet network interface controller card that connects to the motherboard via the now-obsolete ISA bus. This combination card features both a BNC connector (left) for use in (now obsolete) 10BASE2 networks and an 8P8C connector (right) for use in 10BASE-T networks.
12 early ISA 8 bit and 16 bit PC network cards. The lower right-most card is an early wireless network card, and the central card with partial beige plastic cover is a PSTN modem.
A Qlogic QLE3442-CU SFP+ dual-port NIC
An ATM network interface.
Intel 82574L Gigabit Ethernet NIC, a PCI Express ×1 card, which provides two hardware receive queues

The network controller implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet or Wi-Fi.

frame

G.hn

4 links

Specification for home networking with data rates up to 2 Gbit/s and operation over four types of legacy wires: telephone wiring, coaxial cables, power lines and plastic optical fiber.

Specification for home networking with data rates up to 2 Gbit/s and operation over four types of legacy wires: telephone wiring, coaxial cables, power lines and plastic optical fiber.

frame
G.hn protocol stack
Relationship between G.hnta and G.hn

ITU-T Recommendation (the ITU's term for standard) G.9960, which received approval on October 9, 2009, specified the physical layers and the architecture of G.hn.

Physical medium dependent

2 links

Physical medium dependent sublayers or PMDs further help to define the physical layer of computer network protocols.