[CSAL] Comm. and Internet Technologies

Network Topology

  • show understanding of a bus topology network and the implications of how packets are transmitted between two hosts

  • show understanding of a star topology network and the implications of how packets are transmitted between two hosts

In Data communications

  • Sender
  • Receiver
  • Transmission medium - Carry the message, physical
  • Message - Both ends required to have an agreed protocol to send
  • Protocol

Network Topology - how physically devices connected in a single (isolated) network

Name  and diagram Description Adv/Disadv Example
Point-to-point

 
Bus

 
Ring

 
Star
 
Mesh
 
Name  and diagram Description Adv/Disadv
Point-to-point

 		 Two nodes connected directly
Bus

 		 All devices shared a central "Bus", all data sent in a bus is broadcasted
Ring

 		 Each end system has a point-to-point connection to the two adjacent end-systems
Star
 		 All nodes connected to a central device
Mesh
 		 Each node has a point-to-point connections to every single node

Network Hardware Devices

  • show understanding of a wireless network

  • explain how hardware is used to support a LAN: switch, router, servers, Network Interface Cards (NICs), wireless access points

  • show understanding of Ethernet and how collision detection and avoidance (such as CSMA/CD) works

Wireless Networks

Tech Distance Bandwidth Radio Freq Typical Usage Other features
Bluetooth v2
Bluetooth v4
802.11n
802.11ac
1G Voice Comm. Analog Only
2G Voice Comm.
3G
4G
5G

Research and complete the table

LAN hardware

  • Router
    • Routes (path planning) for packet from one network to another
  • Network Interface Card (NIC)
    • The hardware component that allows the device communicate with other devices
  • Wireless Access Point (AP)
    • Hardware device allow other WiFi device to connect to wired network
  • Hub / Switch
    • Provide wired connection to multiple devices, distribute packets to connected devices
    • Central device in a Star network

Hub vs Switch

  • Hub
    • "broadcast" all incoming message
    • i.e. re-transmit to all connected devices
  • Switch
    • inspect the packet to determine the destination of the packet
    • Only forward the message to designated recipient
    • Switch work in Layer 2 (Data link layer) of OSI model, and it inspect the MAC address of the packet

TCP/IP Protocols

  • Show understanding of why a protocol is essential for
    communication between computers
  • Show understanding of how protocol implementation
    can be viewed as a stack, where each layer has its own
    functionality
  • Show understanding of the TCP / IP protocol suite
  • Show understanding of protocols (HTTP, FTP, POP3,
    IMAP, SMTP, BitTorrent) and their purposes

TCP/IP Protocols

  • TCP - Transmission Control Protocol
  • IP - Internet Protocol
  • TCP/IP Suite is a stack of many different protocols:
    • Link Layer (network interface)
    • Network layer
    • Transport layer
    • Application layer
  • Upper layer will communicate with the next immediate layer and relying on it to take care all lower level actions
    • e.g. HTTP (application layer) can send data via any physical layer (e.g. ethernet, bluetooth) without changing any implementation, since it relies on TCP (transport layer) only

OSI compares to TCP/IP model

TCP/IP model with some example protocols

Network Layer (OSI layer 3)

  • Data packets
  • Internet Protocol, IP Address
  • Ensure data packet correctly routed over the Internet
  • Router is a layer-3 device which compares to switch is layer-2
    • Router routes data packets (with IP address)
    • Switch distributes data frames (with MAC address)
    • What about hub?

Ethernet Data Frame

Dataframe vs Data packet

Data is wrapped in different layers across TCP/IP Suite

Transport Layer (OSI Level 4)

  • TCP
    • ensures message is safely delivered to the receiver
    • also ensure response can be directed back to the application protocol
      • On top of IP address, port is defined
      • Port is virtual and refers to different communication channel over the same IP address
    • TCP is connection-oriented, which means a virtual connection will establish between devices, while IP or lower levels are connection-less

Application Protocols

  • HTTP/S
  • FTP
  • Email
  • P2P

FTP

  • File Transfer Protocol
  • Design for clients to upload and download files from a file server
POP3 IMAP SMTP
Full name
Function
Features



 

Email Protocols

P2P Protocol

  • BitTorrent is a peer to peer (p2p) protocol which allows files to be shared, without hosting the files in server
  • https://www.youtube.com/watch?v=6PWUCFmOQwQ
  • Watch and answer:
    • How BT different from downloading from server
    • What is Tracker and Peer

Transmission Modes

  • show understanding of circuit switching and where it is applicable
  • show understanding of packet switching
  • show understanding of the function of a router in packet switching
  • explain how packet switching is used to pass messages across a network, including the Internet

Circuit Switching

  • Circuit switching requires establishing dedicated physical connection between devices
  • Example: Traditional Telephone switching system (PSTN)

Packet Switching

  • Instead of dedicated connection, connections are shared in packet switching
  • Data is splitted into small chunks, call packets
  • Each packet has headers identifying source and destination address, along with other control data
  • Packets take different pathway to the destination
  • On the Internet, packets are forwarded by Router
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