#49 Bad datagram size for UDP IPv6 under FreeBSD

[Olivier Cochard-Labbe]

IPerf use a default size of 1470 byte datagrams when doing UDP IPv6 tests under FreeBSD, but the maximum datagram size is 1430 (IPv4 max datagrams size minus 40 byte because FreeBSD use a MTU of 1480 for IPv6).
All packets generated are fragmented, causing bad throughput result.