IPV6 link-local address functions and principles of the detailed

Local Link Address: link-local

When IPV6 is enabled on one node, each interface of the node at startup automatically generates a link-local address

The prefix 64 bits are specified by the standard and the 64 bits are then constructed in EUI-64 format

Note: On this link, the next hop in the routing table is the link local address to the end, not the public network IP address

Prefix: FE80::/10

Scope: can only be used on local links, cannot route between subnets

How is link-local made up of?

On the composition of link-local, I looked up some of the information on the Internet, many of them are a version, have not written in front of a positive number seventh to be reversed, byte is fe80+ after the 64-bit for the EUI-64, the result is wrong. Here's what I've verified based on some device providers, and the last one on Cisco's website. Here I deliberately organize a legend, so that people better understand how this link-local is composed.

Why do we need link-local?

--a lot of IPV6 addresses can be configured in one interface, so learning routing can be a lot of the next hop.

Therefore, a link local address uniquely identifies a node. On the local link, you see the next hop as the link-side address.

The link local address of the node and the router does not change during the network relocation process, and can easily be modified without worrying about the network unreachable.

R1 (config-if) #ipv6 address fe80:0:0:0:0123:0456:0789:0abc link-local manually specify link-local addresses

So here I did a little experiment to verify that the routing table was a link-local address:

Topology map: (each address has been identified)