1. IPv6 basic packet header
Field Description Version Version number, length 4 bits, value 6 Traffic Class Flow category, equivalent to the TOS field in the IPv4 packet header, indicating the priority of the data message, mainly used for QoS Flow Label Flow label, length 20 bits, used to distinguish real-time traffic Payload Length Payload length, 16 bits Next Header The next header, 8 bits, defines the extension header type Hop Limit Hop limit, 8 bits, equivalent to the TTL field in IPv4 Source Address Source address, 128bits Destination Address Destination address, 128bits
2. IPv6 address format
(1) Use hexadecimal number representation, there are 8 fields in total, such as X:X:X:X:X:X:X:X, X is represented
by hexadecimal number (2) Leading zero can be omitted, such as 2031:0:130F:0:0:9C0:876A:130B
(3) A group of consecutive 0s can be used:: means, but only allowed to be used once, such as FF01:0:0:0:0:0:0: 1 can be expressed as FF01::1
3. IPv6 address type
(1) Unicast
identifies an interface, and the message whose destination address is the unicast address will be sent to the identified interface.
(2) Multicast
identifies multiple interfaces, and the message whose destination address is the multicast address will be sent to all the identified interfaces
(3) Anycast
identifies multiple interfaces, and the message whose destination is the anycast address will be sent The nearest identified interface, the nearest node is defined by the routing protocol
4. EUI-64 address
Use the 48-bit MAC address to insert FFFE in the middle to make up 64 bits to ensure that the selected address is changed from a unique Ethernet MAC address, the 7th bit (U/L bit) 1 is changed to 0, and 0 is changed to 1.
5. Stateless address automatic configuration
Process:
(1) The host sends a Router Solicitation message
(2) The router responds to a Router Advertisement message
(3) The host obtains the prefix and other parameters
(4) The router periodically sends out RA messages
6. IPv6 address configuration
// Enable IPv6
ipv6
// Enable IPv6 on the interface
ipv6 enable
// Manually configure the IPv6 global unicast address
ipv6 address 2001::1/64 
// Configure the IPv6 global unicast address in EUI-64 mode
ipv6 address 2001::/64 
// Manually configure the link local address
ipv6 address FE80::1 link-local 
// Automatically generate the link local address
ipv6 address auto link-local 
// Configure the interface anycast address
ipv6 address 2001::1/64 anycast