IPv4: 32bit address, a "decimal", "dotted", "paragraph 4" record.
IPv4 addresses on the Internet already is not enough, most of the current solutions use NAT technology, at the expense of speed at the expense of maintaining the network traffic.
IPv6: 128bit addresses, using "run (No.) minutes", "Hex", "8 segments" record, and support the "compression notation 0" and "embedded IPv4 address notation." Support plug and play .
3-1-4 rule (Pi rule):
3: represents the global prefix are three 16-bit binary number.
1: Indicates the subnet ID is a 16-bit binary number.
4: Interface ID is four 16-bit binary number.
IPv6 can provide a huge address space, i.e., 2 ^ 128 340 trillion trillion trillion addresses, each piece sufficient sand on earth is assigned an IP address.
(1) unicast (unicast): conventional point to point communication.
(2) Multicast (multicast): a multipoint communication.
(3) anycast (anycast): This is a type of IPv6 increased. Anycast destination station is a set of computers, but at the time of delivery of a datagram delivery wherein only, usually the nearest one.
IPv6 address allocation provides three ways:
1, manually configured global unicast address
Static configuration: similar to IPv4
EUI-64: This arrangement allows you to specify the prefix and prefix length, dynamically generated interface ID.
Unnumbered IP: IP interface to allow other interfaces on the same device.
2, EUI-64 configuration
EUI-64 configuration manually configured prefix autoconfiguration ID interfaces . Generating the interface ID is generated based on the MAC address of the network card. First 48 bits of the MAC address 24 is the OUI (manufacturer code) 24 is a network card ID.
① 48-bit MAC address from the middle into two parts;
② FFFE is inserted between the bit and the OUI identifiers, binary FFFE is 1,111,111,111,111,110. IEEE FFFE is a reserved value used to identify EUI-64 address is generated by a 48 bit MAC address.
③U / L inversion.
U / L (Universally / Locally, the global / local) bit, a byte is the first of seven 'bit, is used to determine that the IPv6 address is a global address or unified management locally administered address, assigned by a 0 indicates IEEE, 1 represents It is a local administrator to configure.
Are U / L at the reverse seems to be some contradictions, some mentioned in the document, when the U / L bit is only 0 should be reversed, but on Cisco devices regardless of the values will be reversed.
3, the unnumbered IPv6 IP configuration occupying another interface of the same device.
SLAAC: When using this method, the length of the prefix and inform the relevant announcement message by the ND router device, and the interface ID EUI-64 created by the process.
DHCPv6: similar to DHCP IPv4, the use of DHCP server automatically assigns IP addresses.
From the IPv4 to IPv6 transition is by no means easy, but step by step, but to use gradual evolution approach , it is also necessary to make the new IPv6 system installed backward compatibility: IPv6 systems must be able to receive and forward the IPv4 packet, and can an IPv4 packet routing.
Two strategies: dual stack and tunneling
Dual-stack (dual stack) means prior to complete transition to IPv6, so that part of the host (or router) is provided with two protocol stacks, a IPv4 and a IPv6. Dual stack host (or routers) referred to as IPv6 / IPv4, indicating that it has both an IP address: an IPv6 address and an IPv4 address. Dual stack host and the IPv6 host communication is employed when the IPv6 address and an IPv4 host and the IPv4 address to communicate. It can be determined using the IPv4 address or an IPv6 address from the address returned by the DNS type.
Tunneling , upon IPv6 packet to the IPv4 network, the IPv6 packet encapsulated into an IPv4 packet, the entire IPv6 packet into an IPv4 datagram data portion. When the IPv4 datagram leaving IPv4 tunnel in the network, then the data portion (i.e., the original IPv6 packet) to the IPv6 protocol stack of the host.
