Chapter 1

Question 1

Point to point (2)

Answer 1

1) Each machine is individually connected with the other machines.
2) Uni casting is a p2p where there are 1 sender and 1 receiver.

Question 2

Broadcast network (3)

Answer 2

1) All machines share the communication channel. The package has the receiver address. The receiver will accept the package and the other machines will refuse it.
2) Broadcasting: sending packages to the whole network.
3) Multi casting: sending packages to a subset of the network.

Question 3

PAN (1)

Answer 3

Private Area network, which allows communication over the range of a person (ex Bluetooth)

Question 4

LAN (4)

Answer 4

1) Local Area Network, allows communication in the range of a building.
2) Enterprise Networks are LANs for companies.
3) VLAN is a virtual division of a LAN in smaller logic LANs.
4) Power Line Networks are LANs which can operate through power outlets.

Question 5

802.11 (1)

Answer 5

1) Each machine uses an access point to communicate with other machines and the internet.

Question 6

802.3 (2)

Answer 6

1) Every machine is connected through a P2P link with a switch.
2) The switch sends the packages to the machine which matches the address.

Question 7

Allocation Methods (2)

Answer 7

1) Static: each machine has a predefined time slot in which it can communicate.
2) Dynamic: channels are allocated by a central entity or by the machines based on their needs.

Question 8

MAN (2)

Answer 8

1) Metropolitan Area Networks allow communication over a city.
2) Television network has been adapted to allow two way communication.

Question 9

WAN (2)

Answer 9

1) Wide area networks connect entire countries or continents.
2) Hosts are connected over a subnet which allows communication.

Question 10

Subnet (3)

Answer 10

1) Composed by Transmission lines and routers.
2) Transmission lines transport the physical bits between machines.
3) Routers are machines that connect two or more TL and decide on which to send the packages.

Question 11

WAN Variations (2)

Answer 11

1) VPN: connects hosts using the internet instead of the TL

2) ISP: the subnet is managed by a NSP which allows connections from multiple customers.

Question 12

Internetworks (2)

Answer 12

1) Networks connected between them through gateways.

2) Usually built and maintained by different companies, and using different technologies.

Question 13

Gateway (1)

Answer 13

1) Machine which allows connection between networks and provides necessary translations.

Question 14

Layers or Levels (1)

Answer 14

1) Offer services to higher levels without sharing implementation details

Question 15

Protocol (1)

Answer 15

1) Set of rules governing format and meaning of packets or messages exchanged with peer entities. machines

Question 16

Network Architecture (1)

Answer 16

1) Set of layers and protocols

Question 17

Protocol stack (1)

Answer 17

1) List of protocols used by a system

Question 18

Interface (1)

Answer 18

1) Defines operations made available to upper layers

Question 19

Physical Medium (1)

Answer 19

1) How machines communicate physically.

Question 20

Connection oriented service (3)

Answer 20

1) Service user establishes a connection, uses it, and when it’s done it releases it.
2) Users negotiate on parameters such as message size…
3) User send bits which are received in the same order as they are sent.

Question 21

Connectionless (3)

Answer 21

1) Each packet contains a destination address and is sent independently.
2) Store-and-forward switching: packet is received fully before sending to next node.
3) Cut through switching: transmission begins before complete reception.

Question 22

Message sequence (2)

Answer 22

1) Connection-oriented service

2) Preserves message boundaries

Question 23

Byte streams (2)

Answer 23

1) Connection-oriented service.

2) Streams bytes without boundaries.

Question 24

Unreliable connection (2)

Answer 24

1) Connection-oriented

2) Used if delays from acknowledgement are not acceptable.

Question 25

Datagram (2)

Answer 25

1) Connectionless

2) Does not send acknowledgement

Question 26

Acknowledged Datagram (2)

Answer 26

1) Connectionless

2) each packet sent expects a return packet which confirms that it was received.

Question 27

Request reply (2)

Answer 27

1) Connectionless

2) the sender transmits a datagram with a request and the receiver replies to the request.

Question 28

Primitives (1)

Answer 28

1) Set of operations available to user processes for a service.

Question 29

Service (1)

Answer 29

1) set of primitives that a layer provides to the layer above it.
2) It is an interface between the service provider and the service user.

Question 30

OSI (6)

Answer 30

1) Connects communicating systems
2) Composed by 7 layers.
3) Each layer performs services for the above layer
4) The layer interface tells how to access the layer.
5) Each layer can use any protocol as long as it provides the declared services.
6) Transport layer only supports connection-oriented communication.

Question 31

TCP/IP (3)

Answer 31

1) Built around protocols
2) Has 4 layers
3) Supports both connection and connectionless communications in the transport layer.