Por que o endereço ipv6 do “link do escopo” pode ser pingado por meio de interfaces nas quais ele não está ativo?

Question

[root @ 2_01 ~] # / sbin / ip -6 addr mostra pubeth0

inet6 2001:1::6/64 scope global
inet6 2001:1::1/64 scope global
inet6 fe80::20c:29ff:fe69:f9e8/64 scope link

[raiz @ v2_01 ~] # / sbin / ip -6 addr mostra pubeth1

inet6 fe80::20c:29ff:fe69:f906/64 scope link

[root @ 2_01 ~] # ping6 fe80 :: 20c: 29ff: fe69: f9e8% pubeth1

PING fe80::20c:29ff:fe69:f9e8%pubeth1(fe80::20c:29ff:fe69:f9e8) 56 data bytes
64 bytes from fe80::20c:29ff:fe69:f9e8: icmp_seq=1 ttl=64 time=0.259 ms
--- fe80::20c:29ff:fe69:f9e8%pubeth1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 286ms
rtt min/avg/max/mdev = 0.259/0.259/0.259/0.000 ms

[root @ 2_01 ~] # ping6 fe80 :: 20c: 29ff: fe69: f9e8% pubeth0

PING fe80::20c:29ff:fe69:f9e8%pubeth0(fe80::20c:29ff:fe69:f9e8) 56 data bytes
64 bytes from fe80::20c:29ff:fe69:f9e8: icmp_seq=1 ttl=64 time=0.057 ms 
--- fe80::20c:29ff:fe69:f9e8%pubeth0 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 390ms
rtt min/avg/max/mdev = 0.057/0.057/0.057/0.000 ms

Por que eu posso pingar "fe80 :: 20c: 29ff: fe69: f9e8" via pubeth1?