Saturday, August 9, 2014
IPv6
(Internet Protocol version 6) is a set of specifications from the Internet
Engineering Task Force (IETF) that's essentially an upgrade of IP version 4
(IPv4). The basics of IPv6 are similar to those of IPv4 -- devices can use IPv6
as source and destination addresses to pass packets over a network, and tools
like ping work for network testing as they do in IPv4, with some slight
variations.
The
most obvious improvement in IPv6 over IPv4 is that IP addresses are lengthened
from 32 bits to 128 bits. This extension anticipates considerable future growth
of the Internet and provides relief for what was perceived as an impending
shortage of network addresses. IPv6 also supports auto-configuration to help
correct most of the shortcomings in version 4, and it has integrated security
and mobility features.
IPv6 features include:
§ Supports source and destination addresses that are
128 bits (16 bytes) long.
§ Requires IPSec support.
§ Uses Flow Label field to identify packet flow for
QoS handling by router.
§ Allows the host to send fragments packets but not
routers.
§ Doesn't include a checksum in the header.
§ Uses a link-local scope all-nodes multicast address.
§ Does not require manual configuration or DHCP.
§ Uses host address (AAAA) resource records in DNS to
map host names to IPv6 addresses.
§ Uses pointer (PTR) resource records in the IP6.ARPA
DNS domain to map IPv6 addresses to host names.
§ Supports a 1280-byte packet size (without
fragmentation).
§ Moves optional data to IPv6 extension headers.
§ Uses Multicast Neighbor Solicitation messages to
resolve IP addresses to link-layer addresses.
§ Uses Multicast Listener Discovery (MLD) messages to
manage membership in local subnet groups.
§ Uses ICMPv6 Router Solicitation and Router
Advertisement messages to determine the IP address of the best default gateway.
