New Contect

Question 1

Define: Transport Entity

Answer 1

Hardware/ Software providing services

Question 2

Why is the transport layer necessary?

Answer 2

IP as network layer is “best effort” so we need transport layer for reliable service

Question 3

What is the key difference between the data link and network layer

Answer 3

Data layer moves frames from one end of a wire to the other, while network layer moves packets globally from source to destination using multiple hops

Question 4

What must the network layer know and choose?

Answer 4

must know the topology of the network and choose appropriate paths accordingly

Question 5

Define Routing

Answer 5

Deciding the overall path for packet/ frame through the network from source to destination through multiple hops/trans

Question 6

Define Forwarding

Answer 6

Local decision made within a router to choose appropriate outgoing link for a given pack/ frame as part of overall path

Question 7

What is important for the routing algorithm?

Answer 7

Correctness important, robustness critical

Fairness and efficiency are also desirable

Question 8

What is the most effective congestion control?

Answer 8

reducing network load cooperatively by network and transport layers

Question 9

What are some issues to consider for achieving the quality of service with less?

Answer 9

application requirements, regulation of traffic, resource reservation, traffic acceptance margin

Question 10

What does the network layer do?

Answer 10

Provides services to the transport layer at the network layer/ transport layer interface
Provides end-to-end packet delivery using datagrams or virtual circuits

Question 11

What are the 5 parts of link state routing?

Answer 11

1. Discover its neighbors and learn their network addresses
2. Determine the link cost (to each of its neighbors)
3. Preoparation of link state packets
4. Distributed Link State Packets
5. Local Shortest-path computation

Question 12

What is the IP Address Resolution Protocol?

Answer 12

in IPv4, enables association of MAC and IP addresses
- When host only has IP addr of destination, broadcases an inquiry to identify owner, which will be the sole responder, providing its MAC address
(ARP request)
- MAC/ IP cached together
- expires after a few minutes to allow mapping change

Question 13

What is the Dynamic Host Configuration Protocol?

Answer 13

in IPv6,

• every server has a designated DHCP server
• New host broadcasts a ‘DHCP discover’ request, which must reach server
• server responds with ‘DHCP’ offer pack that provides an available IP address for host
• addres not permanent

Question 14

What is the transport layers purpose?

Answer 14

to provide a reliable service on top of an unreliable network

Question 15

What are the 5 basic primitives of the transport layer?

Answer 15

Listen, connect, send, recieve and disconnect

Question 16

What are elements of the transport protocols?

Answer 16

• Addressing
• connection establishment
• connection release
• error/ flow control
• multiplexing and inverse multiplexing
• crash recovery

Question 17

Where is conjecstion detected and controlled? and how

Answer 17

Detected in network layer (routers) and controlled in transport layer (hosts) by reducing rate of entry of packets to network

Question 18

What does the user datagram protocol do?

Answer 18

provides a way for applications to send encapsulated IP datagrams without having to establish a connection
- unreliable with no set up

Question 19

What does the transmission control protocol provide?

Answer 19

Reliable service through setup (whereas UDP is unreliable with no setup)
Provide reliable end-to-end byte stream over unreliable inter network

Question 20

What is the transmission (sliding window) policy?

Answer 20

decouples acks and recvr buffer allocation; delayed acks; special algorithms to control with data is sent