Maximum Transmission Unit Determination
A couple of notes to determine the maximum transmission unit (MTU) of a network link...
$ ping -s 1472 server.domain.tld -M do
$ ping -D -s 1472 server.domain.tld
C:\> ping -f -l 1472 server.domain.tld
1472 should work (for
MTU=1500). If not, the results will instruct about the maximum transmission unit, such as:
ping: local error: Message too long, mtu=1480
In that case, it is necessary to lower the MTU value, for example, of a tunnel interface, in iptables, etc.
Note: The static ICMP header size of 8 bytes was changed by RFC1812. Therefore, the size of 1472B is just for the initial testing phase and may differ.
The above details are solely based on a king help provided by the DSLReports FAQ.