Lecture 1

Question 1

Name a few physical communication links used for transmission of data.

Answer 1

Ethernet cables
Copper wire
Optical fiber
Radio waves?
Network interface cards.

Question 2

What are routers and link-layer swtiches (packet switches) used for?

Answer 2

They connect multiple communication links.
A router can connect physical devices togheter with wireless, they are used in lan’s (local area network) by connecting several end systems (pc’s) togheter.

Question 3

What are the basic internet ingredients?

Answer 3

Hosts (end-systems)
- PCs, servers, mobile devices, servers, etc

Packet switches (routers and switches)
- Forward (routes) packets between hosts and packet switches using forwarding (routing) tables.

Communication links
- Enables communication between hosts and packet switches (Copper wires, ethernet cables, fiber optics, wifi)
- Network cards physically connects nodes (hosts, packet switches) to communication links. (Network cards)

Standardised network communication protocols
- Governing the communication between hosts and packet switches

Question 4

The protocols, software and hardware in the Internet is organised in a stack with five layers. Name them in the correct order.

Answer 4

Question 5

Network communication protocols define the rules that govern the communication between the hardware and the software entities. What are the 4 elements of the communication protocols?

Answer 5

• The types of messages exchanged between entities
• The syntax (format) of the messages
• The semantics (meaning) the the message fields
• The processing logic for timing and ordering of message
  exchanges