Backgorounds

Network admins have to cope even with link-locals
when a routing trouble occurs, global addresses might not be used to fix the trouble.
should use a router's link-local to telnet to a bad router

EBGP peering
using specific ISP's global addresses would be unfair
using link-local would be better in a neutral IX
link-local addresses should be specified in a router's configuration file

We should disambiguate links of such link-local addresses;
a router usually connects to multiple links
we can't just type "fe80::1"