IPv6 Advance Features
By
Hamisu Ibrahim Usman
Why Internet Protocol?
An Internet Protocol address (IP address) is a numerical
label(or a hexadecimal in the case of IPv6) assigned to each device (e.g., computer, printer, mobile) participating in a computer network that uses the Internet Protocol for communication.
An IP address serves two principal functions:
host or network interface identification and location addressing.
Its role has been characterized as:
A name indicates what we seek An address indicates where it is A route indicates how to get there
The Internet Assigned Numbers Authority (IANA) manages
the IP address space allocations globally and delegates five regional Internet registries (RIRs) to allocate IP address blocks to local Internet registries (Internet service providers) and other entities.
IPv6 is 128 bits long (16 bytes). Basic architecture is 64
bits for the network number and 64 bits for the host number
The number of IPv6 addresses is 1028 (79 228 162 514 264
337 593 543 950 336) times larger than the number of IPv4 addresses. The text form of the IPv6 address is xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx, where each x is a hexadecimal digit, representing 4 bits. Leading zeros can be omitted.
The double colon (::) can be used once in the text form of
an address to designate any number of 0 bits.
Why IPv6?
IPv4 has not been substantially changed since the publication of
its specifications in 1981.
IPv4 has proved to be robust, easily implemented, interoperable
and scalable enough to enable a global utility of the size of today’s Internet.
However, the initial design did not anticipate IP’s huge
deployment, and several problem snow lead to the deployment of IPv6 include:
The explosive growth of the Internet and the emerging exhaustion
of IPv4 addresses. IPv4 addresses have become relatively scarce.
The growth of the Internet and the ability of Internet backbone routers to
maintain large routing tables.
The need for simpler configuration. Most current IPv4
implementations have to be either manually configured or use a stateful address configuration protocol such as Dynamic Host Configuration Protocol (DHCP).
With more computers and devices using IP, there is a need
for a simpler and more automatic configuration of addresses and other configuration settings.
The IPv6 stateless auto-configuration enables the
deployment of unmanaged networks (for home applications for instance) or fast evolving networks (military applications, crisis management…)
The requirement for security at the IP level. Private
communications over a public medium like the Internet require encryption services that protect the data being sent from being viewed or modified in transit.
Although a standard now exists for providing security for
IPv4 packets (known as Internet Protocol security or IPsec), this standard is optional. The support of IPsec is mandatory in IPv6implementations.
The need for better support for real-time delivery of data,
called as well quality of service (QoS).
QoS also exists for IPv4. Unfortunately, the IPv4 field has
limited functionalities and over time there were various local interpretations. In addition, payload identification may not be possible when IP security is in use.
IPv6 keeps the existing IPv4 (Traffic Class in IPv6) but it can be
enriched with the use of the flow label field in the IPv6 header.
Efficient mobility mechanisms in IP have become critical with
the apparition of new mobile devices such as PDAs or mobile phones.
IPv6 has been designed with efficient built -in mobility
mechanisms.
Address Space
IPv6 has 128-bit (16-byte) source and destination IP
addresses. In addition, the large address space of IPv6 has been designed to allow for multiple levels of sub-netting and address allocation from the Internet backbone to the individual subnets within an organization.
Even with the most pessimistic estimate made by IP
experts, IPv6 would provide 1,564 addresses for each square meter of the surface of the planet.
With a much larger number of available addresses,
address-conservation techniques, such as the deployment of NAT, are no longer necessary.
The New Header Format
The IPv6 header has a new format that is designed to keep
header overhead to a minimum. This is achieved by moving both non-essential fields and option fields to extension headers that are placed after the IPv6 header.
The streamlined IPv6 header provides more efficient
processing at intermediate routers. IPv4 and IPv6 headers are not interoperable. A host or router must use an implementation of both IPv4 and IPv6 in order to recognize and process both header formats.
The new IPv6 header is only twice as large as the IPv4 header,
even though IPv6 addresses are four times as large as IPv4 addresses.
Efficient and Hierarchical Addressing and Routing
Infrastructure
IPv6 global addresses used on the IPv6 portion of the
Internet are designed to create an efficient, hierarchical, and summarizable routing infrastructure that is based on the common occurrence of multiple levels of Internet service providers.
On the IPv6 Internet, backbone routers have much smaller
routing tables, corresponding to the routing infrastructure of Top-Level Aggregators (TLA)
Stateless and Stateful Address Configuration
To simplify host configuration, IPv6 supports both stateful
address configuration (such as address configuration in the presence of a DHCP server) and stateless address configuration (address configuration in the absence of a DHCP server).
With stateless address configuration, hosts on a link
automatically configure themselves with IPv6 addresses for the link (called link-local addresses) and with addresses derived from prefixes advertised by local routers.
Even in the absence of a router, hosts on the same link can
automatically configure themselves with link-local addresses and communicate without manual configuration.
The same mechanism can also be used in order to
configure the default router address in the hosts.
Built -in Security
Support for IPsec is an IPv6 protocol suite requirement.
This requirement provides a standards-based solution for network security needs and promotes interoperability between different IPv6 implementations
Built -in Mobility
IPv6 mobility mechanisms benefit from the IPv6
auto-configuration features and the flexibility of IPv6 header extensions. Mobility was taken into account from the very beginning of IPv6 design, making Mobile IPv6 implementations more efficient than IPv4 ones.
Standard in IPv6
Key distribution
Photuris (zero-knowledge key exchange) Based on Diffie-Hellman protocol
Authentication
Keyed MD5
Encryption
DES-CBC
See from RFC 2401 to RFC 2412
Multicast Support
From the start, multicast has also been taken into account
in IPv6. Multicast support is mandatory in IPv6 implementations, and IPv6 devices are dimensioned for multicast.
Better Support for QoS
New fields in the IPv6 header define how traffic is
identified and handled. Traffic identification using a Flow Label field in the IPv6 header allows routers to identify and provide special handling for packets belonging to a flow, a series of packets between a source and destination
.
The interaction of QoS with IPsec is handled by the IPv6
implementation, even when the packet payload is encrypted.
New Protocol for Neighboring Node Interaction
The Neighbor Discovery Protocol for IPv6 is based on
ICMPv6 (Internet Control Message Protocol for IPv6) and manages the interaction of neighboring nodes (nodes on the same link).
Neighbor Discovery replaces the broadcast-based Address
Resolution Protocol (ARP), ICMPv4 Router Discovery and ICMPv4 Redirect Messages.
The IPv6 Dead Peer Detection is much more efficient than
the ARP one.
