Data Transmission and Network Interconnection

Posted on Aug 24, 2024 in Computers

Data Transmission Methods

According to Transmission:

Series: All signals are transmitted via a single line of data sequentially.

Parallel: Transmitting a group of bits simultaneously, one for each line of the canal.

According to Transmitted Signal:

Analog and Digital, Baseband or Broadband: (modulated signal)

Exploitation of Data Systems:

Simplex: It has clearly defined the roles of issuer and receiver, and the transmission is unidirectional.

Half Duplex: The communication may be bidirectional but not simultaneously. Has a single physical channel and one logical channel.

Duplex: Bidirectional and Simultaneous. There is one physical channel and two logical channels.

Modulation and its Advantages

Modulation: Modification of the carrier wave to better tailor their properties to the media in question, to represent the message.

Advantages of Modulation:

  • Facilitates Propagation
  • Regulates the Radio Spectrum
  • Decreases Size of the Antenna
  • Optimizes Bandwidth
  • Avoids Interference between channels
  • Protects against Noise
  • Defines the Quality of information transmitted

Transmission Problems

Attenuation: Weakening of the signal due to electrical resistance.

Distortion: Signal deformation produced normally because the channel behaves differently at each frequency.

Interference: Addition of a known signal and undesired signal is transmitted.

Noise: Sum of multiple interference of unknown and possibly random nature.

Interconnection Basics

Modems

Modem: A device that allows a computer to send and receive information through the RTC, which transmits an analog signal. May be internal or external. There are plenty of standards. We have 2 types:

  • Those related to communication between computer and modem
  • Those that specify the type of communication between two modems over a phone line

Network Cards

Network Card: Performs the role of intermediary between the computer and communication network. In it are recorded the communication protocols of the network physical level, data link, and network. Communication with the computer is by the expansion slots. The steps performed to transmit are:

  1. To determine the characteristics of the system
  2. Converting the bit stream in parallel with a sequence number
  3. Changing the serial bit stream to form a suitable electrical signal

Parts of a Network Card:

  • Main Processor: (Make communication operations)
  • Connection Bus: (Route between the network card and the computer bus)
  • BIOS ROM Socket: (Used to insert a memory ROM)
  • Transceiver: (Gives access to the network transmission medium and can be installed on the card or you can connect to it from the outside with the appropriate cable. Is responsible for detecting the carrier signal flowing through the middle and collisions that may occur)
  • Wake On LAN Connector: (Connects through a cable card and the motherboard allowing remote start the computer)
  • Status Indicators

Repeaters, Amplifiers, and Concentrators

Repeaters: Used in digital transmission.

Amplifiers: Used in analog transmission.

Limitations of Amplifiers and Repeaters: The sections of cable that separate always have a maximum length, and the signal cannot traverse an infinite number of amplifiers.

Concentrator Cabling: Centralizes the connections between stations in a single device while maintaining its status indicator lights and preventing one of them from crashing the entire network. There are 2 types:

  • Passive: (Acting as a simple hub to connect the network)
  • Active: (Also amplify and regenerate the signals)

It also has 2 types of connections:

  • One for stations
  • Another to connect to other hubs

The topology is a star, with the hub in the center. Are classified depending on how they make connections and internally distributed messages:

  • Hubs with Logic Topology Bus (HUB): (Make the network behave as a bus. The bus behaves like a broadcast medium, therefore producing collisions)
  • Hubs with Logic Topology Ring (MAU): (Sends the signal that comes through a port to the next. The communication protocol should check that station can transmit to avoid collisions)
  • VPN Concentrators: (Used to create private networks, allowing virtual teams communication for clients connected to the internet)

The connection between two MAU is done through 2 Special RI and RO ports provided in parallel.

Wireless Networking

Wireless Access Points: Devices that centralize network connections.

Wireless Networking Cards: Devices that communicate with the network stations.

Aspects to Consider When Assembling a Wireless Network:

  • Note that each access point has enough coverage to reach all computers that have the necessary power.
  • Taking into account the difficulty that will be the signal to reach different places and interference that may cause other appliances.

Network Interconnection: Bridges

Bridges: Allow interconnecting networks of different topologies and different MAC level protocols and levels of link. Make the necessary adjustments to a LAN to another so you can exchange information. Consist of 2 different connectors coupled to the corresponding network. They behave like ordinary seasons, without any privilege over the rest. A bridge acts as a filter on the network. It can be used to connect 2 LAN peers. Can be constrained in 2 ways:

  • Hardware: (Bridge hardware is a specific device for interconnecting LANS)
  • Software: (A bridge is a computer software that behaves as such. Must be installed 2 network cards together with a program that would give the bridge behavior.)

Bridge Rates:

  • From 802.x to 802.y: Used to connect networks of IEEE 802.
  • Transparent: Allow complete transparency, to install does not require any modification to the networks that are being installed. Works in promiscuous mode.
  • Remote: Allows 2 or more LAN interfaces that are separated to a great distance. A wireless access point can be considered a bridge if you have RJ45.