IPv6 link local address generate automatically if IPv6 package is enabled. For enabling IPv6 you may follow this post
[admin@Mikrotik] > /ipv6 address print
Flags: X - disabled, I - invalid, D - dynamic, G - global, L - link-local
# ADDRESS FROM-POOL INTERFACE
0 DL fe80::e97:42ff:fef5:7a00/64 ether1
1 DL fe80::e97:42ff:fef5:7a03/64 ether4
2 DL fe80::e97:42ff:fef5:7a01/64 ether2
3 DL fe80::e97:42ff:fef5:7a02/64 ether3
4 DL fe80::dcac:40ff:feed:b345/64 loopback-1
Unlike IPv4, IPv6 link local address are crucial for routing. So if the address is removed mistakenly it will make routing problem.
[admin@Mikrotik] > /ipv6 address print
Flags: X - disabled, I - invalid, D - dynamic, G - global, L - link-local
# ADDRESS FROM-POOL INTERFACE
0 DL fe80::e97:42ff:fef5:7a03/64 ether4
1 DL fe80::e97:42ff:fef5:7a01/64 ether2
2 DL fe80::e97:42ff:fef5:7a02/64 ether3
3 DL fe80::dcac:40ff:feed:b345/64 loopback-1
4 G 2000:5a40:0:11::2/126 ether1
As you can see, though static IPv6 is configured on the interface , still the address is showing unreachable
How to regenerate link local IPv6 address on Mikrotik when deleted ?
The solution is quiet simple, simply reset (disable and re-enable) the interface. This applicable for all type of interface Ethernet/VLAN/bridge. For minimum impact on live traffic you may try following method
/interface ethernet disable 0; enable 0
Result,
[admin@Mikrotik] /interface ethernet> /ipv6 address print
Flags: X - disabled, I - invalid, D - dynamic, G - global, L - link-local
# ADDRESS FROM-POOL INTERFACE ADVERT
0 DL fe80::e97:42ff:fef5:7a03/64 ether4 no
1 DL fe80::e97:42ff:fef5:7a01/64 ether2 no
2 DL fe80::e97:42ff:fef5:7a02/64 ether3 no
3 DL fe80::dcac:40ff:feed:b345/64 lo-1 no
4 G 2000:5a40:0:11::2/126 ether1 no
5 DL fe80::e97:42ff:fef5:7a00/64 ether1 no
