IPv6 extends the 32-bit IP address in IPv4 to 128 bits. IPv4 addresses are binary numbers represented as decimals, while IPv6 addresses are binary numbers represented as hexadecimal. The IPv4 protocol has a 32-bit address length, while the IPv6 protocol has a 128-bit address length. The IPv6 address length is 4 times the IPv4 address length; an IPv6 IP address consists of 8 address sections, each section contains 16 address bits, the total The length is 16x8=128 bits.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
IPv6 extends the 32-bit IP address in IPv4 to 128 bits.
IPv6 is the abbreviation of "Internet Protocol Version 6" in English. It is the next generation IP protocol designed by the Internet Engineering Task Force (IETF) to replace IPv4. Its address The quantity claims to be able to assign an address to every grain of sand in the world.
The biggest problem of IPv4 is the insufficient network address resources, which seriously restricts the application and development of the Internet. The use of IPv6 can not only solve the problem of the number of network address resources, but also solve the obstacles for multiple access devices to connect to the Internet.
IPv6 is designed to replace IPv4. However, IPv4 has still occupied a dominant position in Internet traffic for a long time, and the use of IPv6 has grown slowly. In April 2022, the percentage of users using Google services through IPv6 exceeded 40% for the first time.
The IPv6 address length is 128 bits, which is 4 times the IPv4 address length. An IPv6 IP address consists of 8 address sections, each section contains 16 address bits, and the total length is 16x8=128 bits.
So the IPv4 dotted decimal format is no longer applicable and is expressed in hexadecimal.
IPv6 has 3 representation methods:
1. Hexadecimal representation
The format is X:X:X:X:X:X:X:X, where each X represents 16b in the address, expressed in hexadecimal, for example:
ABCD:EF01: 2345:6789:ABCD:EF01:2345:6789
In this notation, the leading 0 of each X can be omitted, for example:
2001:0DB8:0000:0023: 0008:0800:200C:417A→ 2001:DB8:0:23:8:800:200C:417A
2. 0-bit compressed representation
in a certain In some cases, an IPv6 address may contain a long period of 0s, and the continuous period of 0s can be compressed into "::". However, to ensure the uniqueness of address resolution, "::" can only appear once in the address, for example:
FF01:0:0:0:0:0:0:1101 → FF01::1101
0:0:0:0:0:0:0:1 → ::1
0:0:0:0:0:0:0:0 → ::
3. Embedded IPv4 address representation
In order to achieve IPv4-IPv6 interoperability, the IPv4 address will be embedded in the IPv6 address. At this time, the address is often expressed as: X:X:X ::X: Typical example, note that in the first 96b, the method of compressing 0 bits is still applicable
The difference between IPv4 and IPv6 protocols
1. The difference between protocol addresses
1), address length
The IPv4 protocol has a 32-bit (4-byte) address length; the IPv6 protocol has a 128-bit (16-byte) address Length
#2), address representation method
IPv4 address is a binary number expressed as a decimal. IPv6 addresses are binary numbers represented in hexadecimal notation.
3) Address configuration
The IPv4 protocol address can be configured manually or through DHCP. [Recommended related video tutorials:HTTP video tutorial]
The IPv4 protocol requires the use of Internet Control Message Protocol version 6 (ICMPv6) or DHCPv6 Stateless Address Autoconfiguration (SLAAC).
2. Differences in data packets
1) Packet size
IPv4 protocol data packets require 576 bytes, fragmentation is optional . The IPv6 protocol data packet requires 1280 bytes and will not be fragmented
2), the header
The length of the IPv4 protocol header is 20 bytes, and does not recognize data for QoS processing Packet stream, including checksum, containing options field of up to 40 bytes.
The IPv6 protocol header is 40 bytes in length and contains the Flow Label field of the packet flow specified for QoS processing, excluding checksum; the IPv6 protocol has no field, but the IPv6 extension header is available.
3) Packet fragmentation
IPv4 protocol packet fragmentation will be completed by the forwarding router and the sending host. Packet fragmentation of the IPv6 protocol is only done by the sending host.
Data packet
3. DNS record
IPv4 protocol address (A) record, mapping host name; pointer (PTR) record, IN-ADDR.ARPA DNS domain.
IPv6 protocol address (AAAA) record, mapped host name; pointer (PTR) record, IP6.ARPA DNS domain
4, IPSec support
IPSec support for the IPv4 protocol is optional only. The IPv4 protocol has built-in IPSec support.
5. Address Resolution Protocol
IPv4 Protocol: Address Resolution Protocol (ARP) can be used to map IPv4 addresses to MAC addresses.
IPv6 protocol: Address Resolution Protocol (ARP) is replaced by the functionality of Neighbor Discovery Protocol (NDP).
6. Authentication and encryption
Pv6 provides authentication and encryption, but IPv4 does not.
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