alt Hacker News"IPv6 is weird. One of the more strange parts of the standard is that every interface's link local addresses are in fe80::whatever`."
How is IPv6 weird here, it's the exact same thing in IPv4, no? If you have two different network interfaces, you have to identify which is which somehow, either by assigning a specific IP range to it or by adding some kind of identifier.
Making zones part of addresses in the first place was probably a mistake, I agree, but the problem of address conflicts when users can choose arbitrary addresses certainly isn't a design flaw of IPv6.
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A link-local address necessarily needs a way to specify a link, and the link is local to the sending host and not something the receiving host knows. I suppose they could have used the upper address bits, but the sending host would need to know to convert them to 0 when sending the packet out on the wire, and with the interface ID when receiving.
I think the weirdness comes from the use of multiple addresses at once, specifically fe80::whatever addresses always being present and getting used even on normal setups when everything's working fine and a global address is configured, as opposed to 169.254.whatever addresses, which most networks never intend to use and so usually only show up when something is wrong.
The title of the post suggests the issue is allowing that syntax in URLs.
Is there an equivalent syntax for IPv4 addresses?
> you have to identify which is which somehow
The _routing_ system does. You have the same problem if you have multiple public IPs on a machine. Your local routing will not automatically return packets back through the address they came to. They will go to the _default_ route. So if you have this configuration you need to setup either the routing tables or the firewall to re-route packets "back out" the proper interface or IP address.
This is strictly a routing problem and not an addressing problem.
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There aren't address conflicts. And users aren't choosing this, it's part of the IPv6 spec. Each interface has a unique address, but you can't tell from looking at an address which network it lives on.