IPv6
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Background on IPv6
IPv4 address space has been exhausted, and the nearly unlimited address space is the biggest advantage of IPv6
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IPv6 basic header
Based on IPv4, flow labels are added and some redundant fields are removed to make the processing of message headers simpler and more efficient.
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IPv6 extension header
It is an optional header following the IPv6 basic header. There can be one or more
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IPv6 address format
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The length of an IPv6 address is 128 bits, and each 16 bits is divided into a segment. Each segment is represented by 4 hexadecimal numbers and separated by colons.
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IPv6 address consists of two parts: network prefix and interface identifier.
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The leading 0's in each group can be omitted
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A consecutive group of all 0s contained in the address can be replaced by a double colon "::"
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IPv6 address classification
IPv6 addresses are divided into unicast addresses, anycast addresses, and multicast addresses
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Global unicast address
With a fixed prefix, similar to the public network address of IPv4
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link local unicast address
The link local unicast address prefix bit FE80::/ identifies the interface on the link and is automatically generated.
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multicast address
All IPv6 multicast addresses start with FF, identifying a group of interfaces
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anycast address
Use an address to identify a group of network interfaces, belonging to different nodes.
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IPv6 stateless address autoconfiguration
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The network node sends an RS to the connected router to request address prefix information.
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The router replies with address prefix information by sending a router advertisement RA.
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EUI-64 specification
Insert FFFE into the middle of the MAC and reverse the 7th position to generate the interface ID.
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IPv6 stateless address DAD check
When configuring an IPv6 address for an interface, DAD is used to check whether the IPv6 address to be used is unique within the local link range (gratuitous ARP)