L2 - Architecture and Principles

Question 1

Internet’s sub problems

Answer 1

1) Multiplexing (sharing) - solved with packet switching.

2) Interconnection of existing networks - solved with ‘narrow waist’ of IP

Question 2

Packet- switching characteristics

Answer 2

1) Variable Delay

2) Sharing of network resources

Question 3

Circuit-switching characteristics

Answer 3

1) Busy Signals

2) Dedicated Resources between Sender and Receiver

Question 4

What are the 5 layers of the protocol stack?

Answer 4

5 - Application Layer (e.g. HTTP, SMTP)
4 - Transport Layer (TCP or UDP)
3 - Network Layer (IP)
2- Link Layer (includes Ethernet)
1 - Physical Layer

Question 5

What is the end-to-end argument?

Answer 5

intelligence required to implement a particular application on the communication system should be placed at the end points rather than the middle of the network. “Dumb network, intelligent endpoints”. Allowed the internet to grow rapidly.

Question 6

What are some end-to-end argument violations?

Answer 6

• Network address translators (NAT)
• VPN tunnels
• TCP splitting (happens often when last hop is wireless)
• Spam filters
• Peer 2 Peer systems
• Caches