Which protocol is responsible for managing retransmission? the ethernet protocol or tcp or both?

Question

I wonder which protocol is responsible for managing retransmission? the ethernet protocol or tcp or both?

I was attending a TCPIP course and it is not clear for me which protocol is responsible for managing retransmission

Answer 1

To answer your question, TCP handles retransmission of corrupt frames. Ethernet only detects it.

Systems communicating over Ethernet divide a stream of data into shorter pieces called frames. Each frame contains source and destination addresses, and error-checking data so that damaged frames can be detected and discarded; most often, higher-layer protocols trigger retransmission of lost frames. Per the OSI model, Ethernet provides services up to and including the data link layer.

So the “responsibility” is on TCP. Note that speaking of responsibilities is misleading. You can have UDP (OSI layer 4) over Ethernet (OSI layer 2) in which case the “responsibility” for handling missing data is on the application which may choose to NOT resend (I.e. video streaming in which it doesn’t make sense).

On other data link protocols the resending of frames can be built into the protocol itself.

In that sense, handling retransmissions would be more of a property or feature of the TCP protocol rather than a “responsibility”