Network

Question 1

What is forwarding?

Answer 1

A process in which a packet arrives at a router then later output to the next router

Question 2

What is routing

Answer 2

Determine the best route for packet delivery

Question 3

What is VC & its characteristics?

Answer 3

• connection oriented data transmission
  ~ data transfer stays on source & destination path
  ~ requires buffer & bandwidth thus costly

Question 4

What is datagram?

Answer 4

• connectionless data transmission in small units by all intermediate routers
  ~ packet consisting of destination address header

Question 5

What are the routing algorithms?

Answer 5

1. distance vector
2. link state
3. hierarchical

Question 6

What are the 3 routing methods?

Answer 6

1. Routing Information Protocol
2. Open Shortest Path First
3. Border Gateway Protocol

Question 7

What is RIP & how it works

Answer 7

• Routing Information Protocol
  ~ determine best path via hop count
  ~ 1 router = 1 hop (max=15)
  ~ exchange with neighbour for 30s, after 180s no response, send new advertisement to new neighbour
  ~ < hop count = best path

Question 8

What is OSPF & how it works?

Answer 8

• Open Shortest Path First
  ~ determine best path by mapping out networking link
  ~ gather link state information, map out network, network based on dest ip address, compute shortest path using Dijksha algorithm

Question 9

What is BGP & how it works?

Answer 9

• Border Gateway Protocol
• determine path by exchanging routing & reachability among autonomous system
• information from iBGP & eBGP, advertise prefix & forward datagram

Question 10

What is IPv4

Answer 10

• 32 bit address to identify host & network route

Question 11

How to get IPv4 address?

Answer 11

Domain Host Configuration Protocol
- device connects to router
- device DHCP request is being encapsulated downwards
- request then receive by DCP server
- demux the request at server side
- DHCP ACK send from server which later encapsulated
- demux at client’s end which receive ip address

Question 12

IPv4 subnet & NAT

Answer 12

• consists of 3 network subnet & 1 host subnet
• Network Address Translation
  ~ convert local address to public NAT address

Question 13

what is IPv6?

Answer 13

-128 bit address

Question 14

Why use IPv6?

Answer 14

solve IPv4 limitation & issues with NAT

Question 15

What is IPv6 subnet?

Answer 15

• consists of 8 subnet portions
• 0/1 is 4 hexa bits = 16 bits
• has global subnet, subnet ID (organization) & interface ID (host)

Question 16

What is selective repeat pipeline?

Answer 16

• only retransmit the selective unACK packet
• sender keeps time for each not ACK packet