I made a file /etc/sysconfig/network-scripts/route6-eth0 with the following contents:
default dev eth0 src ****:****::**** metric 50 pref medium
However, it doesn't show up when I execute ip -6 route:
# ip -6 route
::1 dev lo proto kernel metric 256 pref medium
****:****:****:****::/64 dev eth0 proto ra metric 100 pref medium
****:****::**** dev eth0 proto kernel metric 100 pref medium
fe80::/64 dev eth0 proto kernel metric 100 pref medium
default via ****::****:****:****:**** dev eth0 proto ra metric 100 pref medium
I did the same for IPv4, and there it works fine, /etc/sysconfig/network-scripts/route-eth0 contents:
default dev eth0 src ***.***.***.*** metric 50
ip route:
# ip route
default dev eth0 proto static scope link src ***.***.***.*** metric 50
default via ***.***.***.*** dev eth0 proto dhcp metric 100
***.***.***.*** via ***.***.***.*** dev eth0 proto dhcp metric 100
***.***.***.***/23 dev eth0 proto kernel scope link src ***.***.***.*** metric 100
My goal with this config is to change the default source address, which works for IPv4. I think the route6 is not working because of router advertisements, but that's just a guess. Maybe the RA overrides the routes.