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Re: Evolution of the IP model - ICMP and MTUs
Thanks Dan for the ref. to RFC 4963. I had not noticed this RFC,
important as far as the evolution of the IPv4 model is concerned.
IMU, since it shows that, at high data rates, IPv4 fragmentation can
lead to undetected data corruption at the IP layer, it implies that
fragmentation SHOULD be discarded from an updated IPv4 service model
(the DF bit MUST be set in all packets).
Applications that can send datagrams longer than typical MTUs (AFAIK,
Sun NFS needs 8 K) can still work in strict conformity with the IP
model, but in IPv6.
With no fragmentation in the IPv4 model, packet losses due to
insufficient reassembly resources are no longer a concern.
Where ICMP is not filtered by FWs, upper layers can take advantage of
MTU information which, since RFC 1191 of 1990, may be returned in Packet
too Big ICMP massages.