Lecture 4 - Computer Networks and Hardware Essentials

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Network Communication 

- Kilobit = 1000 bits

- Kilobits per second is shortened to kb/s, Kbps or kbps.

- 1 kb/s = 1000 bits per second

- 1 KB/s = 1024 bytes per second

- Download KBPS speed = ((Kbps value * 1000) / 8) 1024.

Components of Networks

- Hardware components needed:

   * Network interface card (NIC) is a hardware component, typically a circuit board, which is installed on a computer so it can connect to a network.

   * Interconnecting device allows two or more computers to communicate on the network without direct connection.

2. Software Components

  • Network client software requests information stored on another network computer.
  • Network server software allows a computer to share its resources.
  • Protocols are the rules and formats a computer must use while interacting in a network.
  • NIC driver receives data from protocols and forwards it to physical NIC.

Layers of Network Communication Process

Layer is the steps required for a client to access network.

1. User application: An application tries to access a network.

2.  Network software: Software detects the attempt of access and passes the message on to the network protocol.

3. Network protocol: The protocol packages the message and sends it to the NIC driver.

4. Network interface: The NIC driver forwards it to NIC card which converts it into the signals to be transmitted across the network medium.

TCP (Transmission Control Protocol) / IP (Internet Protocol) is the most common protocol:

1. Logical address - IP address

2. Physical address - MAC address 

IP address is like name of the receiver and MAC address is like postal address.

CIDR (Classless Inter-Domain Routing) is an IP address allocating method.

Broadcast IP address: is a network address used to transmit to all devices connected to a multiple-access communications network.

An internetwork is collection of LANs tied together by routers.

Two or more groups LAN need to be logically separated but still need to communicate and is no longer efficient.

Network Terminology

Private IP Address: Used for communicating within your private network.

192.168.0.0 - 192.168.255.255 

172.16.0.0 - 172.31.255.255 

10.0.0.0 - 10.255.255.255 

Public IP Address: Used for communicating outside your private network.

Packet: data leaving the computer grouped into small chunks and have IP address added to it.

Information is carried as bursts of about 1500 bytes.

Advantages of data carried out in burst is:

  • Pause between bursts allows transfer data.
  • Allows the receiving computer to receive and process received data.
  • Gives the sending computer time to receive data and perform processes.
  • Only the chunks of data involved in the error have to be sent again if transmission is failed. 

Frame: a packet with the source and destination MAC addresses added to it

Encapsulation: the process of adding IP addresses and MAC addresses to chunks of data.

Information added to the front of a packet is called a header (MAC address) and information added to the end is called a trailer (Frame tailer).


 



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