Error control in Transport Layer vs Data Link Layer?
I understand that under the TCP/IP Protocol Suite, error control, flow control and other such services are provided by both, the Transport Layer and the Data Link Layer.\n\nMy doubt is specific to error control using the Sliding Window protocol (used by the Transport Layer, if I'm not mistaken) and the Stop-and-Wait ARQ (used by the DLL). Do both these processes occur (in the context of the respective layers) *simultaneously?* Or is it *one or the other*? \n\nI also understand that for the Transport Layer, we are concerned with *frames* at either end points, whereas for the DLL, we are concerned with *frames* at each *hop* that a frame makes. Thus, my confusion is this: when we refer to *frames* in both Sliding Window and Stop-and-Wait ARQ, which Layer's PDU's are we talking about? How do these two processes occur?