Chapter 32

Question 1

What is the difference between ipv6 and ipv4

Answer 1

ipv6 has optional headers, format change, source and destination addresses has longer space (16 Octets, 4 times bigger than ipv4).

Question 2

What is path MTU

Answer 2

Host finds out MTU size of whole network in path and then it must choose a datagram that fit in the minimum MTU size of that path or in other words, the minimum MTU size that is chosen along the path is called path MTU.

Question 3

What is path MTU discovery

Answer 3

The method tp chose path MTU is called path MTU discovery.

Question 4

What is the purpose of multiple/extension headers

Answer 4

There are 2 advantages of multiple headers

1. Economy (IPv6 saves the space)
2. Extendible (we can add different features and protocol in IPv6)

Question 5

What is IPv6 addressing

Answer 5

There are hierarchy of addressing in IPv6 addressing

Question 6

What are 3 special types of addressing

Answer 6

1. Unicast: Single destination computer
2. Multicast: Multiple destinations; possibly not at same site
3. Cluster: Collection of computers with same prefix; datagram is delivered to one computer out of cluster.

Question 7

What is IPv6 colon hexadecimal notation

Answer 7

IP addresses representation in IPv6. 128 bit addresses requires 16 numbers

Question 8

What is zero compression

Answer 8

IPv6 addresses often contain consecutive hexadecimal fields of zeros. To simplify address entry, you can use two colons (::) to represent the consecutive fields of zeros when typing the IPv6 address. For example
Original format: 1234:1234:0000:0000:0000:0000:3456:3434
Using zero compression: 1234:1234::3456:3434

Question 9

What is ARP in IPv6

Answer 9

In ARP(Address Resolution Protocol), we can bind IP addresses to corresponding hardware addresses. And after binding we can deliver those addresses to hardware level.

Question 10

What is ICMP

Answer 10

Internet control message protocol is an error reporting mechanism that reports back.

Question 11

What is best effort delivery

Answer 11

IP is best effort delivery. It means they can be late, duplicate, lost and out of order. All these errors can be present but IP does not have to deal with it. There are other layers in TCP/IP suit that deals with them.

Question 12

Why checksum present in IP datagram

Answer 12

For discard errors in certain situations

Question 13

What are 2 types of ICMP messages

Answer 13

1. Error messages

2. Information messages

Question 14

What are examples of error messages

Answer 14

• Source quench
• Time exceeded
• Destination unreachable
• Redirect
• Parameter problem

Question 15

What is Source quench error message

Answer 15

Whenever IP discard new datagram due to buffer limit problem, it sends source quench message to the host so it change the rate of transmission.

Question 16

What is time exceeded error message

Answer 16

Time exceeded message is sent in 2 cases.

1. Whenever router reduce TTL field to zero
2. If reassembly time expires

Question 17

What is destination unreachable error message

Answer 17

When router can not deliver ip datagram to its destination, destination unreachable error message send back to host. It tells destination, the reason of destination unreachable. Either network down or destination individual computer down.

Question 18

What is redirect error message

Answer 18

When message directed to wrong router and router redirect it.

Question 19

What is parameter problem error message

Answer 19

When parameter is missing or wrong

Question 20

What are examples of Information messages

Answer 20

• Echo request/reply
• Address mask request/reply
• Router discovery