IPv6

Lets discuss regarding IPv6. Feel free to post your queries or answers..

1. What is IPv6 ?
    It is the protocol with capabilities to replace/upgrade IPv4.

2. Difference between IPv6 and IPv4 addresses ?
    a. IPv4 uses decimal number as numbering format for ip address
        IPv6 uses hexadecimal number as numbering format for ip address
    b. IPv4 is 32-bit numeric address
        IPv6 is 128-bit address in hexadecimal
    c. IPv4 uses class-based addressing
        IPv6 uses classless addressing

3. What is the need for IPv6 ?
     a. Limitation in address space offered by IPv4
     b. Absence of security features on its own in IPv4
     c. Limitation in data prioritization / QoS offered by IPv4

4.How will you port an application from IPv4 to IPv6 ?
   The system calls should be updated with appropriate arguments as per IPv6.

5. How will you represent an IPv6 address ?
    It shall be represented as 8 groups of 4 hexadecimal digits separated by colons.

6. How could the IPv4 address exhaustion could be handled ?
    There are various approaches like Subnetting/CIDR, NAT/PAT, Use of Private networks & DHCP

7. What changes are made in header for IPv6 ?
    All unnecessary information and options that are present in IPv4 are moved to the end of IPv6 header

8. What is the size of IPv6 header ?
     IPv6 header has a fixed header size of 40 bytes, whereas the IPv4 header has a variable length due to options field.

9. Which fields are same in IPv4 and IPv6 ?
    Version field, Type of Service (IPv4) is similar as Traffic Class(IPv6), Total
    length(IPv4) is somewhat similar as Payload length(IPv6), TTL (IPv4) is same as Hop
    Limit(IPv6), Protocol(IPv4) is somewhat similar as Next Header(IPv6)

10.What is the additional field in IPv6 that is absent in IPv4 ?
     Flow label for sequencing of packets

11. Which fields have been eliminated/deleted in IPv6 from that of IPv4 ?
      Header checksum, Header length & Fragmentation fields are eliminated. The Options field is moved into payload

12. What are the new features with IPv6 ?
      a. Stateless auto configuration
             i) No need for DHCP
            ii) New host can assign its own host address
      b. New IP security protocols
             i) Authentication of source
           iii) Encryption of payload
      c. Jumbo payload option that can carry packet upto 4GB

13. What ways IPv6 devices can be deployed ?
      a. By Tunneling IPv6 over IPv4
      b. Using Dual stack router that supports both IPv4 and IPv6
      c. Using a NAT device for translation between IPv4 and IPv6