10 things you need to know about IPv6

In the past few years, IPv6 has gradually become the mainstream, but many IT professionals are still helpless when facing IPv6. Indeed, IPv6 and IPv4 are quite different, this article is intended to help you eliminate IPv6 phobia.

1. The IPv6 address is a 128-bit hexadecimal number.

An IPv4 address consists of a total of 32 digits in four digit groups. The IPv6 address length is 128 bits and consists of hexadecimal characters. In IPv4, each bit group consists of 0-decimal digits, which are separated by English periods. IPv6 addresses are composed of eight groups, each bit group consists of a 4-character hexadecimal number.

2. It is easy to identify the local Unicast address of the link.

IPv6 retains special address headers for different address types. The most obvious example is that all local unicast addresses on the Link start with PE80 and multicast addresses start with FF0x, here, x is a placeholder. you can replace it with numbers 1-8.

3. abbreviation of supported addresses

Because IPv6 addresses are long and often contain many zeros, if all characters in a bit group are 0, these zeros can be abbreviated as 0. For example, the following address:

FE80: CD00: 0000: 0CDE: 1257: 0000: 211E: 729C

Can be abbreviated

FE80: CD00: 0: CDN: 1257: 0: 211E: 729C

4. Consecutive 0 values can be omitted.

If all the characters in multiple consecutive single-digit groups are 0, all 0 values can be omitted. For example, the following address:

FE80: CD00: 0000: 0000: 0000: 211E: 729C

In addition to the abbreviations described in Article 3rd, you can also omit consecutive 0 values and replace them with two colons. After the Operating System displays the IPv6 address, naturally, the characters between them are all 0. Therefore, the preceding address can be abbreviated

FE80: CD00: 211E: 729C

5. IPv6 loopback address

In IPv4, we know that the loopback address is a special address pointing to the local machine, that is, we are familiar with 127.0.0.1, and IPv6 is no exception. We also designed the loopback address, as shown below:

0000: 0000: 0000: 0000: 0000: 0000: 0000: 0001

Refer to the 4th omitted statement, and the IPv6 loopback address becomes

: 1

Does this look like a valid IP address.

6. The traditional subnet mask is not required.

In IPv4, each IP address must be used with a subnet mask. IPv6 also uses the subnet concept, but the subnet ID is directly embedded in the address. In IPv6, the first 48 bits indicate the network prefix, followed by the 16-bit subnet ID, and the last 64 bits indicate the interface ID, that is, the interface ID or device ID. If necessary, the bit reserved for the device ID can be used to represent an additional subnet mask, but this is usually not required, because the 16-bit subnet and 64-bit device ID can provide up to 65536 subnets.

7. IPv6 still needs DNS

In IPv4, host record is A record) ing IP addresses to host names. IPv6 still uses DNS technology, but IPv6 no longer uses host records. On the contrary, IPv6 uses AAAA resource records, ip6.arpa is used for reverse host name resolution.

8. IPv6 tunnel communication across IPv4 networks

One reason why IPv6 cannot be effectively promoted is that it is not fully compatible with IPv4. As a result, the tunnel technology for IPv6 communication on IPv4 networks appears, one is Teredo and the other is 6to4, although they work in different ways, the basic idea is to encapsulate IPv6 data packets into IPv4 data packets for transmission, but both ends of the communication must have the ability to package and unpackage.

9. You may already be using IPv6

Starting from Windows Vista, Microsoft has installed the IPv6 driver by default and enabled the IPv6 protocol by default, because it is automatically configured and you may not know it yet, however, IPv6 is not enough only for the operating system. All vswitches and vrouters must support IPv6. In addition, some poorly designed applications hard-code IPv4 addresses into the program, they are all obstacles to IPv6 popularization.

10. Windows does not fully support IPv6

Although Microsoft is very active in supporting IPv6, Windows does not fully support IPv6. For example, in Windows, we can use the UNC general naming convention in the past) access to the Internet shared folder such as \ 127.0.0.1 \ C $), but IPv6 cannot be used now, because when Windows sees the colon in the IPv6 address, it treats it as a drive letter.

To solve this problem, Microsoft has created a special domain for IPv6 address translation. If you use an IPv6 address in a UNC path, you must use a break number instead of a colon, and add the suffix .20.6.literal.net at the end of the address, for example, FE80-AB00-200D-617B.ipv6.literal.net.