> It's local system policy, how do I react to packets. If it doesn't > violate the min/max limits for ipv6 packets it emits onto the internet > I don't see this as something that can be seen as mandatory.
And if you *truly* do want to violate internet standards you can indeed already achieve this behaviour by dropping incoming icmpv6 packet too big errors (and there's lots of reasons why that is a bad idea...). I'll repeat what I said previously: this is a userspace visible regression in behaviour, of none or very questionable benefit. It results in TCP over IPv6 simply not working to destinations to which your locked mtu is higher then the real path mtu. This is why 'locked mtu' on IPv4 turns of the Don't Fragment bit - to allow fragmentation at intermediate routers. There is no such thing in IPv6. There is no DF bit, and there is no router fragmentation - all ipv6 fragmentation is supposed to happen at the source host. This is why hosts must either use 1280 min guaranteed mtu or be responsive to pmtu errors. Otherwise things simply don't work.
