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by WhyNotHugo 8 days ago
It's not the same as IPv4. IPv4 doesn't solve this problem. If eth0 and eth1 are both 169.254.0.20 on two different networks, you can't specify that you want to ping 169.254.0.1 on a specific interface. There's no way to disambiguate both destinations.
2 comments
fragmede 8 days ago
https://linux.die.net/man/8/ping

ping takes a -I argument you specify which interface to use.

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sznio 8 days ago
except in ipv4 getting a link-local address means "I fucked up DHCP" and isn't really meant to be a feature it didn't really work in ipv4 land, and as per the OP, doesn't work in ipv6 land too. Just give everything a proper address and leave link-local to mdns or whatever it was meant to support
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throw0101a 8 days ago
> except in ipv4 getting a link-local address means "I fucked up DHCP" […]

No, it means "there is no infrastructure on this link segment". No router (to send out IPv6 RAs), and (as you say) no (working) DHCP server.

Still being able to have network connectivity automatically in this scenario can still be handy. If mDNS is running on things, then the user doesn't even have to bother manually setting an address: the link light comes on and you have connectivity to the local segment.

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