Encapsulation

Hello there. I have a small question...
When passing down data on the osi layers with encapsulation which percentage of the data received of the physical layer is the actual message?

e.g Message 100byte, Ip header 20 byte, TCP header 20 byte, ethernet header 14 byte and ethernet tailer 4 byte.

It's like... Message/58byte *100% ? or there are some additional bytes?

Thanks a lot!

Infact there can be some additional data added by the physical layer for signaling or encoding. For example Manchester encoding (which is used in Ethernet) adds a preamble to allow for synchronisation, the preamble consists of 64 alternating 1s and 0s sent before the frame.

Other encodings such as the 4B/5B exist which encodes each 4bits as a 5bit pattern to provide for synchronization.