To reproduce:
# ip li add name dummy0 type dummy
# site_id=$(head -c6 /dev/urandom | od -tx2 -An | tr ' ' ':')
# for ((i = 0; i < 65536; i++)) do
> ip ad ad $(printf fd80$site_id::%04x $i)/128 dev dummy0
> done
# (ulimit -s 900; getent ahosts localhost)
# ip li de dummy0