Vault sync: 2021-11-03 23:36:47

School/Analyse/Layers/2. Datalink Layer.md

@@ -3,4 +3,21 @@ The Data Link Layer is responsible for handling the data transfer between two de
 
 The Data Link Layer also splits up packets into smaller chunks called a frame. The reverse happens on the receiving device (reassembling frames into packets).
 
-Like the Network Layer the Data Link Layer is also responsible for flow control and error checking. However it only does this for inter-network communications. (Local network)
+Like the Network Layer the Data Link Layer is also responsible for flow control and error checking.
+
+## Error detection
+Transmissions are not always error free. In case of an error, it should be detected and the message should be re transmitted (whenever possible)
+
+Detecting errors are handled by different algorithms:
+- Parity bits
+- CRC
+
+## Data Framing
+Data is split up in smaller chunks called frames. For each frame we add some extra data:
+
+- Who is sender?
+- Who is receiver?
+- Length of chunk
+- Type of chunk (normal message, error me)
+- Error checking values (ex. CRC code)
+- Data and metadata are put in single message called frame