Question Error Detection And Error Checking In The OSI Model

Nov 9, 2021
I learned that the LLC sublayer of Data Link layer is responsible for Error Detection and Error Correction.
However, while I read some articles, I found out that the transport layer carries out Error Checking. I'm really confused about this.
I guess it depends on what you call a "error". I mean it is done even at the application level.

Things done at the data link layer are very simple in nature. They look for bit that get damaged basically.

If look at say as tcp session as a example it can detect things like packets out of order or packet fragmentation issues. These are a much more complex concept than a bit get damaged. It also detect issues where thing like the ip headers are being changed by routers in the path and something gets set wrong and the router upstream can detect this.

Note pretty much the only data link layer that does "correction" other than very simplistic corrections is wifi. Almost everything else just discards data that is damaged and force a higher layer to do the corrections. So the higher layers must detect and fix what is now loss of large amounts of data rather than just a bit that is wrong.
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