ACCESS TO THE NETWORK

ACCESS TO THE NETWORK

1. TYPES OF CONNECTIONS

   • Physical connection, completely depends on the configuration of the network. For example, in many corporate offices, employees have desktops or laptops that are physically connected, via cables, to a shared switch. This type of configuration is called a wired network. The data is transmitted through a physical cable.
   • Wireless connection, for laptops, tablets and smartphones. In the case of wireless devices, the data is transmitted by radio waves. As people and businesses discover the advantages of offering wireless services, the use of wireless connectivity is becoming more frequent. To offer wireless capabilities, devices that are in a wireless network must be connected to a wireless access point (AP).

2. NETWORK INTERFACE CARDS

   • Network interface cards (NICs) connect a device to the network
   • Ethernet NICs are used for cable connections. In terms of performance, a cable connection will not cause performance degradation.
   • Wireless Local Area Network (WLAN) NICs are used for wireless connections. In terms of performance, a wireless device will experience a decrease in performance depending on the distance it is from the wireless access point. The further away from the access point the device is, the weaker the wireless signal it receives will be. This may mean lower bandwidth or the absolute absence of a wireless connection.
     • Devices for end users may include one type of NIC or both. A network printer, for example, can only have an Ethernet NIC and, therefore, must be connected to the network through an Ethernet cable. Other devices, such as tablets and smartphones, may contain only one WLAN NIC and must use a wireless connection

3. PHYSICAL LAYER

   • The OSI physical layer provides the means of transporting the bits that make up a frame of the data link layer through the network means. This layer accepts a complete frame from the data link layer and encodes it as a sequence of signals that are transmitted in the local media. A final device or an intermediate device receives the coded bits that make up a frame.
     • - The transport layer segments the user data, the network layer places them in packets and the data link layer encapsulates them in the form of a frame.
     • - The transport layer segments the user data, the network layer places them in packets and the data link layer encapsulates them in the form of a frame.
     • - Then, these signals are sent through the media one at a time.
     • - The transport layer segments the user data, the network layer places them in packets and the data link layer encapsulates them in the form of a frame.

4. MEDIA OF THE PHYSICAL LAYER

   • There are three basic formats of network media. The physical layer produces the representation and the groupings of bits for each type of medium in the following way:
     • - Copper cable: the signals are electric pulse patterns.
     • - Fiber optic cable: signals are light patterns.
     • - Wireless connection: the signals are microwave transmission patterns.

5. BANDWIDTH

   • The bandwidth is the capacity of a means to transport data. The digital bandwidth measures the amount of data that can flow from one place to another in a given period of time. The bandwidth is usually measured in kilobits per second (kbps), megabits per second (Mbps) or gigabits per second (Gbps). Sometimes, the bandwidth is thought of as the speed at which the bits travel, however, this is not adequate. For example, in Ethernet of 10 Mbps and 100 Mbps, bits are sent at the speed of electricity

6. PERFORMANCE

   • Performance is the measure of bit transfer through the media during a given period of time, due to different factors, the performance generally does not match the bandwidth specified in the physical layer implementations. Many factors influence performance, including the following:
     • - The amount of traffic
     • - The type of traffic
     • - Latency created by the number of network devices found between origin and destination

7. TYPES OF PHYSICAL MEANS

   • This physical layer produces the representation and grouping of bits in voltages, radiofrequency and light pulses, the standards for copper media are defined as follows:
     • - Type of copper wiring used
     • - Communication bandwidth
     • - Type of connectors used
     • - Pin diagram and color codes of connections to media
     • Maximum distance of the media

8. COPPER MEDIA

   • These cables are used to interconnect nodes on a LAN and infrastructure devices, such as switches, routers, and wireless access points. Each type of connection and its complementary devices include cabling requirements stipulated by the standards of the physical layer; There are three main types of copper media that are used in networks:
     • - BRAIDED TORQUE UNATTENDED (UTP): Unshielded twisted pair (UTP) wiring is the most common network medium. UTP cabling, which is terminated with RJ-45 connectors, is used to interconnect network hosts with network intermediary devices, such as switches and routers.
     • - ARMORED BRAIDED TORQUE (STP): The shielded twisted pair (STP) provides better protection against noise than UTP wiring. However, compared to the UTP cable, the STP cable is much more expensive and difficult to install. Like the UTP cable, the STP uses an RJ-45 connector.
     • - COAXIAL: The coaxial cable gets its name from the fact that there are two conductors that share the same axis, the coaxial cable consists of the following:
       • A copper conductor used to transmit electronic signals.
       • A layer of flexible plastic insulation that surrounds the copper conductor.
       • On this insulating material, there is a woven copper mesh or a metal sheet that acts as a second thread in the circuit and as a shield for the internal conductor. The second layer or shield reduces the amount of external electromagnetic interference.
       • The entire cable is covered by a coating to prevent minor physical damage.

Bilder und Dateien der Mindmap