3. Communication Flashcards
First layer in the TCP/IP 5-layer stack model name and role (3)
Physical layer
- Transmits raw data
- Consists of hardware such as switches and routers
- Deals with all aspects of setting up and maintaining a link between communicating computers
Second layer in the TCP/IP 5-layer stack model name and role
Data link layer
- Sends data from the network layer (contains routers) to the physical layer (to transmit raw data)
- Divides the data to be sent into data frames
- Handles the acknowledgements sent from receiver - handshaking
- Ensures incoming data has been received correctly
Third layer in the TCP/IP 5-layer stack model name and role
Network layer
- Responsible for the addressing and routing of data
- Includes routers to direct data from sender to reciever
Fourth layer in the TCP/IP 5-layer stack model name and role
Transport layer
- Ensures data is transferred from one point to another reliably and without errors
- Responsible for making sure data’s sent and received in correct order
- Acts as an interface between communicating computers and the network
Fifth layer in the TCP/IP 5-layer stack model name and role
Application Layer
- Provides interfaces to the software to allow it to use the network
IP address definition
An address using the Internet Protocol which can uniquely identify every device on the internet, thus allowing communication between them
How does DNS work?
- User types website’s name into browser
- Browser sends it to a DNS server
- Server checks in its database and finds corresponding IP address
- This unique address is then used to route you to the appropriate webpage
Circuit switching defintion
Provides a dedicated link between 2 nodes; no other data can be transmitted along same route while the connection’s open; e.g. landline phone system
Circuit switching ✅ and ❌
✅Reliable, fast once connection established, error free
❌Takes time to establish connection
Packet switching definition
Data is split into packets which are routed (along the best route) along the network by routers and then reassembled e.g. The Internet
Packet switching ✅ and ❌
✅Don’t need dedicated line, can take alternative routes, efficient - only one packet needs to be re-sent
❌Could arrive in wrong order, delay til all arrived, large memory to hold packets until all arrived
Contents of a TCP/IP packet (6)
- Source address
- Destination address
- info allowing reassemblage (no. split into, the packet’s no.)
- the data
- a checksum that checks the data hasn’t been corrupted
Ring network - describe
Nodes are connected in a ring - each node connects to 2 others
Ring network ✅and ❌
✅High transfer speeds - no collisions/bottleneck - single path in one direction - simple definition
❌ if one node fails, network fails
Bus network definition
Nodes are directly connected to a common linear cable/bus
Bus network ✅and ❌
✅Cheap and easy to set up and add new nodes
❌Not that secure
Can be slow if heavy traffic
Break in main bus - break network
How data is transferred in ring and bus network
Message is sent along - location check if it’s for it - not for it them passes on to next node - if for it - download
Mesh network definition
Uses direct communication between each node
Mesh network ✅ and ❌
✅reliable
✅very robust- no single point which will bring down network
✅data can be routed both via other nodes and directly transported
❌expensive and complex to set up
Wired network ✅ and ❌
✅ transmission speeds are faster and more secure
❌ difficult and expensive to install
Wireless network ✅and ❌
✅ mobile equipment can log in
✅ easy and cheap to install
❌ can be hacked more easily
❌ transmissions speeds slow as more users join
Network definition
A collection of computing devices connected together
Network ✅ and❌
✅ share hardware, software and data
✅ computers can communicate
✅ administration can be centralised
✅ can log onto any device
❌ viruses can spread to all computers ❌hackers can access whole network
❌can be pricey
❌slower
LAN definition
Local area network
Computer systems are all located relatively close to each other
