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This article mainly introduces how to classify ipv6 addresses, with certain reference value, friends who need it can refer to. I hope you all have a lot to gain after reading this article. Let's take a look at it together.

IPv6 address classification method: 1, unicast address, a unicast address corresponds to an interface, data packets sent to unicast address will be received by the corresponding interface;2, multicast address, a multicast address corresponds to a group of interfaces, data packets sent to multicast address will be received by all interfaces of this group.

IPv6 address classification method:

For IPv4 addresses, we know that they are divided into Class A, Class B, Class C, multicast addresses and reserved addresses. There are several categories in Class ABC addresses, such as broadcast addresses and private addresses. How are IPv6 addresses classified? This article takes everybody preliminary understanding.

Let's talk about why it's called preliminary understanding, because so far, IPv6 address classification standards are still being formulated, the latest draft standard was formulated in 2006 (see RFC4291 for details), so this article can only lead you to taste fresh, IPv6 address classification and structure have a general understanding. Just like IPv6 standard took 20 years to change from draft to formal standard, the determination of IPv6 address classification standard is also a long process. Of course, with the rapid popularization of IPv6, the determination of this standard will definitely accelerate.

1. IPv6 address representation method

IPv6 addresses have a total of 128 bits. For ease of manual reading and input, IPv6 addresses can also be represented by a string of characters like IPv4 addresses. IPv6 addresses are represented in hexadecimal notation, and IPv6 addresses are divided into 8 blocks of 16 bits each, separated by ":" between blocks. As follows:

At the same time, when multiple address blocks are 0, you can use the "::" sign to simplify.

Principle of simplification:

+ All 0 blocks "0000" can be simplified to "0"

+ Multiple 0 blocks, can be simplified to "::"

+ Only one "::" can appear in an IPv6 address. When multiple 0 blocks appear,"::" to simplify the longest segment, if there is no longest segment, the nearest one (left)

+"::" can appear at the beginning or end of an address

Specific examples are as follows:

IPv6 address types

IPv6 addresses are divided into three categories as a whole: unicast addresses, anycast addresses, and multicast addresses.

Unicast address: A unicast address corresponds to an interface, and data packets sent to the unicast address will be received by the corresponding interface;

Anycast address: an anycast address corresponds to a group of interfaces, and data packets sent to the anycast address will be received by one of the interfaces in this group. Which interface will be received is determined by the specific routing protocol.

Multicast address: A multicast address corresponds to a group of interfaces, and data packets sent to the multicast address will be received by all interfaces of this group;

The specific address allocation is shown in the following figure. Anycast exists in unicast addresses, and there is no special distinction:

Address type specified:

Unspecified address, mainly used at the beginning of the system startup, when IP has not been allocated, when requesting an IP address, it is used as a source address, and it cannot be used in the destination address of the packet.

Loopback address, used when sending packets to oneself, can test the network layer protocol state in daily network troubleshooting.

Local link unicast address, the prefix of local unicast address is FE80::/64, its role is in the network where there is no route (gateway), the host generates IPv6 address through MAC address automatic configuration, can only be used in the local network.

IPv6 address space is allocated by IANA, details can be found on its website.

In addition:php to ipv4 address translation are: ip2long() and long2ip()

Thank you for reading this article carefully, hope Xiaobian share ipv6 address how to classify the content to help everyone, but also hope that everyone more support, pay attention to the industry information channel, encounter problems to find, detailed solutions waiting for you to learn!

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