N2. Basic Architecture

Question 1

Internet Protocol Reference Model.
List Layers
A
T
N
L
Ph

Answer 1

Internet Protocol Reference Model.
A - Application layer
T - Transport layer
N - Network layer
L - (Data) Link layer
Ph - Physical layer 
(Extra layers in application layer (OSI):
presentation and session layers)

Question 2

Protocol at Application-level

Answer 2

Hyper Text Transfer Protocol (HTTP)

Question 3

Protocols at Transport-level

Answer 3

Transmission-Control Protocol (TCP)

User Datagram Protocol (UDP)

Question 4

Protocol at Network-level

Answer 4

Internet Protocol (IP)

Question 5

Internet protocol (IP) key points

Answer 5

• IP is independent of sub-network tech
• IP is the common layer for internetworking
• need to ‘map’ IP onto sub-networking technology

Question 6

Protocol definition

Answer 6

Code prescribing strict adherence to correct etiquette and precedence i.e. instructions/rules that must be followed.

Question 7

Protocol, definitions of message formats

Answer 7

• data structures
• application programming interface (API)
• messages for data, signalling and management

Question 8

What is a connection-less protocol (CL)?

Answer 8

• Send and receive data (datagrams) - no connection set up
• “Send and forget” - typically unconfirmed (confirmed if possible)
• Suitable for “bursty” data

Question 9

What is a connection-oriented protocol (CO)?

Answer 9

Three phases: 
- connection establishment
- data transfer
- connection release 
Connection management: 
- signalling (latency)
- connection state 
- typically confirmed service

Question 10

What is Encapsulation?

Answer 10

(hide most background info but still need some info available)
When we send data/info across network need additional info:
- destination and source addresses
- info about message ordering
- info about message formatting
- protocol, size, error control etc.

Question 11

Message format

Answer 11

Header (and possible trailer) + Payload/Body

[trailer] [payload] [header] —> to network

Header - stores info about message for protocol
Payload/Body - message carried in that layer
(payload increases at each level as the header and trailer from the layer above are consumed into body).