Access to the network

Access to the network

1. Physical layer protocols

   • Physical layer connection
     • Types of connections
       • Network interface cards (NICs) connect a device to the network. Ethernet NICs are used for cable connections, as shown in the figure
   • Purpose of the physical layer
     • 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.
     • Physical layer media
       • Copper cable: the signals are electric pulse patterns. Fiber optic cable: signals are light patterns. Wireless connection: signals are microwave transmission patterns.
     • Physical layer standards
       • The Internet Engineering Task Force (IETF) defines the services and protocols of the TCP / IP suite.
   • Characteristics of the physical layer
     • Bandwidth
     • performance
       • The amount of traffic The type of traffic The latency created by the number of network devices found between source and destination
     • Types of physical media

2. Network media

   • Copper wiring
     • Characteristics of copper cabling
       • The networks use copper media because they are inexpensive and easy to install, and have low resistance to electric current. However, copper media are limited by distance and signal interference.
     • Copper media
       • Unshielded twisted pair (UTP) Shielded twisted pair (STP) Coaxial
     • Security of the copper means
       • All three types of copper media are vulnerable to electrical and fire hazards. The danger of fire exists because the coating and insulation of the cables can be flammable or produce toxic fumes when they are heated or burned.
   • UTP cabling
     • Estándares de cableado UTP
       • The UTP cabling complies with the standards set jointly by the TIA / EIA. In particular, the TIA / EIA-568 stipulates commercial cabling standards for LAN installations and is the most widely used standard in LAN cabling environments.
     • UTP connectors
       • UTP cables are usually terminated with an RJ-45 connector. This connector is used for a variety of physical layer specifications, one of which is Ethernet.
     • Types of UTP cables
   • Fiber optic cabling
     • Design of fiber optic media cables
       • The optical fiber is composed of two types of glass (core and coating) and an outer protective shield (coating). Click on each component of the figure for more information.
     • Fiber optic connectors
       • The three most popular types of fiber optic connectors: ST, SC and LC.
     • Test fiber optic cables
       • Misalignment: fiber optic media does not align precisely when joined. Separation of the ends: there is no complete contact of the means in the connection or the connection. Finishing: the ends of the media are not well polished or dirt can be seen on the finish.
   • Wireless media
     • Types of wireless media
     • Wireless LAN
       • Punto de acceso inalámbrico (AP) Adaptadores NIC inalámbricos

3. Data link layer protocols

   • Purpose of the data link layer
     • The data link layer
       • It allows the upper layers to access the media. Accepts layer 3 packages and packages them in frames. Prepares the network data for the physical network.
     • Data link sublayers
     • Media access control
     • Provision of access to the media
       • The router in the figure has an Ethernet interface to connect to the LAN and a serial interface to connect to the WAN. As the router processes frames, it will use the services of the data link layer to receive the frame from a medium

4. Media access control

   • Topologies
     • Control of access to the media
     • Physical and logical topologies
   • WAN topologies
     • Common WAN physical topologies
       • Point to point: this is the simplest topology, consisting of a permanent link between two terminals. Hub-and-spoke: is a WAN version of the star topology, in which a central site interconnects branch sites through point-to-point links. Mesh: this topology provides high availability, but requires that each end system be interconnected with all other systems.
     • Point-to-point physical topology
     • Logical topology point to point
   • LAN topologies
     • LAN physical topologies
     • Half duplex y Full duplex
       • Half-duplex communication: the two devices can transmit and receive in the media but can not do it simultaneously. Full duplex communication: both devices can transmit and receive in the media at the same time.
     • Methods of control of access to the environment

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