14 Sep
2019
14 Sep
'19
4:01 a.m.
Peter Jeremy:
NFS ran much faster when you turned off the UDP
checksums as well.
(Though there was still the Ethernet CRC32).
Dave Horsfall:
Blerk... That just tells you that the packet came across the wire more or
less OK.
=====
UDP (and TCP) checksums are nearly useless against
the sort of corruption Larry described. Since they
are a simple addition with carry wraparound, you
can insert or remove any number of word-aligned pairs
of zero octets without the checksum changing.
I discovered this the hard way, while tracking down
a kernel bug that caused exactly that sort of corruption.
Does IPv6 require a meaningful checksum, or just the
useless old ritual one?
Norman Wilson
Toronto ON