Advantages of link local address in IPv6

Replace both routers G0/0/0 Interface IPv6 Address , But the business on both sides is not interrupted
The topology is as follows

R1 Of G0/0/0 Interface IPv6 The address is 2003::1  LoopBack 0 IPv6 The address is 2001::1
R2 Of G0/0/0 Interface IPv6 The address is 2003::2  LoopBack 0 IPv6 The address is 2002::1

The configuration command is as follows ：

R1

[Huawei]ipv6
[Huawei]int LoopBack  0
[Huawei-LoopBack0]ipv6  enable  
[Huawei-LoopBack0]ipv6  address  2001::1 128（ Configure the ring return address ）
[Huawei]int g0/0/0
[Huawei-GigabitEthernet0/0/0]ipv6  enable  
[Huawei-GigabitEthernet0/0/0]ipv6  address  2003::1 64
[Huawei]ripng
[Huawei]int lo 0
[Huawei-LoopBack0]ripng 1 enable  （ Enable ripng agreement ）
[Huawei-LoopBack0]int g0/0/0
[Huawei-GigabitEthernet0/0/0]ripng 1 enable  

R2

[Huawei]ipv6
[Huawei]int LoopBack  0
[Huawei-LoopBack0]ipv6  enable  
[Huawei-LoopBack0]ipv6  address  2002::1 128
[Huawei]int g0/0/0
[Huawei-GigabitEthernet0/0/0]ipv6  enable  
[Huawei-GigabitEthernet0/0/0]ipv6  address  2003::2 64
[Huawei]ripng
[Huawei]int lo 0
[Huawei-LoopBack0]ripng 1 enable  
[Huawei-LoopBack0]int g0/0/0
[Huawei-GigabitEthernet0/0/0]ripng 1 enable

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use ping ipv6  -a 2001::1 2002::1 The command shows that the bilateral routers are interconnected

If in IPv4 Modify the routers of both sides in the network g0/0/0 Interface IP The network connection will definitely be interrupted
But in IPv6 You can modify it at will in the network g0/0/0 The interface of IP
You can use ping ipv6  -c 10000 -a 2001::1 2002::1 This order continues ping Package testing

And the reason is that IPv6 The next hop address in the link is the link local address
The routing protocol works on the local address of the link
You can use dis ipv6 routing-table protocol  ripng see
Pictured ：