Joe Maimon wrote:
So IPv6 fixes the fragmentation and MTU issues of IPv4 by how exactly?
Completely wrongly.
Or was the fix incorporating the breakage into the basic design?
Yes. Because IPv6 requires ICMP packet too big generated against multicast, it is designed to cause ICMP implosions, which means ISPs must filter ICMP packet too big at least against multicast packets and, as distinguishing them from unicast ones is not very easy, often against unicast ones. For further details, see my presentation at APNIC32: http://meetings.apnic.net/32/program/apops How Path MTU Discovery Doesn't work Masataka Ohta
In IPv4 I can make tunneling just work nearly all of the time. So I have to munge a tcp mss header, or clear a df-bit, or fragment the encapsulated packet when all else fails, but at least the tools are there. And on the host, /proc/sys/net
FYI, IETF is trying to inhibit clearing DF bit explicitly with draft-ietf-intarea-ipv4-id-update-05.txt >> IPv4 datagram transit devices MUST NOT clear the DF bit. which is now under the last call. Masataka Ohta