On Wed, Jan 12, 2022 at 03:57:55PM +0100, Peter Bergin wrote: > IEEE 802.3 minimum PDU size is 64 bytes. PTP messages SYNC, FOLLOW_UP and > DELAY_REQ is smaller than that, 58 bytes. Are there any spec telling how to > send PTP messages smaller than 64 bytes on Ethernet?
FWIW, the minimum length of an Ethernet frame includes the 32-bit frame check sequence (FCS), i.e. the minimum payload length (assuming no VLAN tags, etc) is 46 octets. The minimum length of a PTP message is 44 octets, so at most 2 octets are needed to pad a PTP message to the required length. If more padding is needed, the PTP specification allows messages to be padded to (almost) any length with the PAD TLV, but I'm not sure if it is supposed to be the only way. -- Miroslav Lichvar _______________________________________________ Linuxptp-users mailing list Linuxptp-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-users
