fragmentation
termnetworking
Splitting a packet because it is larger than a link along the path will carry.
It is the classic source of faults that pass every simple test: small packets work, the connection establishes, and transfers hang once real data starts. That happens when the message asking the sender to reduce its size is filtered, which is common because the message is ICMP and somebody blocked ICMP as a precaution. Tunnels make it routine by adding headers to packets already sized for the original path, which is why the first question about any VPN complaint is the effective maximum size.
Also known as: ip fragmentation