14 Aug
2014
14 Aug
'14
8:19 p.m.
If you look inside the ICMP packet in wireshark, it will tell you who sent it and what MTU they said was acceptable.
Well, I'm definitely drowning in network confusion here :-).
Everyone's MTU is the default 1500, I checked all systems in the path.
The wireshark display says 1516 in the Length column for the NFS packet that always shows up before the ICMP errors. If I expand the "IP V4" line in the packet, it says "Total Length: 1500" for that READDIRPLUS Reply which says 1516 for the capture length. It also has the "Don't fragment" flag set.
It looks like the 16 byte extra is confusing it, but I have no idea why that is different than the IPv4 length info.