Quality of Service and performance characterization of IPv6 relative to IPv4

II.8 UPPER-LAYER PROTOCOL

A protocol layer that is immediately above IPv6. The impact of IPv6 on upper-layer protocols is minimal because the datagram service has not changed substantially. This section discusses UDP and TCP over IPv6 and describes changes for upper-layer protocols, such as DNS, DHCP when used over IPv6.

II.8.1 DHCPv6

The Dynamic Host Configuration Protocol (DHCP) is a set of rules used by a communications device (such as a computer, or router) to allow the device to request and obtain an IP address from a server which has a list of addresses available for assignment, without requiring a manager to configure information about the computer in a server database.^29(*)

The DHCPv6 enables DHCP servers to pass configuration parameters such as IPv6 network addresses to IPv6 nodes.

II.8.2 IPv6 and the Domain Name System

This section defines the changes that need to be made to the Domain Name System (DNS) to support hosts running IPv6. The DNS is the most important applications that have to run on IPv6 before anyone can use. The changes include a resource record type to store an IPv6 address, and a domain to support lookups based on an IPv6 address.^30(*)

Current support for the storage of Internet addresses in the Domain Name System (DNS) can not easily be extended to support IPv6 addresses since applications assume that address queries return 32-bit IPv4 addresses only.

To support the storage of IPv6 addresses in the DNS, Two new DNS record types have been defined for IPv6 hosts to map a domain name to an IPv6 address.

· New Resource Record Type (AAAA)

«A record type» is used for storing an IP address (specifically, an IPv4 32-bit address) associated with a domain name. So a new one was created to allow a domain name to be associated with IPv6 128-bit address, this new one is called «AAAA record type (also called quad-A records)». This new AAAA has been added to support IPv6 address.

The four «A»s («AAAA») are used to indicate that the IPv6 address is four times the size of the IPv4 address. It is the equivalent of IPv4 A record.

A host that has more than one IPv6 address has an AAAA record for each address.

· A6 type record ^31(*)

This new record types support renumerable and aggregatable IPv6 addressing.

A6 is defined to map a domain name to an IPv6 address, with a provision for indirection for leading "prefix" bits.

* ²⁹ http://en.wikipedia.org/wiki/DHCPv6 (May 22, 2006)

* ³⁰ http://www.faqs.org/rfcs/rfc3596.html (May 23, 2006)

* ³¹ http://www.faqs.org/rfcs/rfc2874.html (October 21, 2006)