Lecture slides from the 3rd-year module on Computer Networks at the University of Birmingham, UK.
This presentation covers the Data-Link layer of the networks stack, primarily Error Control, Flow Control and Framing.
35. Hamming Codes w/ Logarithmic Parity 0 0 0 0 0 0 0 0 0 0 0 0 r 1 r 2 m 1 r 3 m 2 m 3 m 4 r 4 m 5 m 6 m 7 m 8 1 2 3 4 5 6 7 8 9 10 11 12 r 4 (8) r 3 (4) r 2 (2) r 1 (1) 12 11 10 9 8 7 6 5 4 3 2 1
36. Hamming Codes w/ Logarithmic Parity ? ? 0 ? 0 1 0 ? 1 1 0 0 r 1 r 2 m 1 r 3 m 2 m 3 m 4 r 4 m 5 m 6 m 7 m 8 1 2 3 4 5 6 7 8 9 10 11 12 r 4 (8) r 3 (4) r 2 (2) r 1 (1) 12 11 10 9 8 7 6 5 4 3 2 1
37. Hamming Codes w/ Logarithmic Parity 1 0 0 1 0 1 0 0 1 1 0 0 r 1 r 2 m 1 r 3 m 2 m 3 m 4 r 4 m 5 m 6 m 7 m 8 1 2 3 4 5 6 7 8 9 10 11 12 r 4 (8) r 3 (4) r 2 (2) r 1 (1) 12 11 10 9 8 7 6 5 4 3 2 1
74. Putting it all together… DATA a chunk of network-layer binary data
75. Putting it all together… ESC DATA ESC bytes or 0 bits stuffed
76. Putting it all together… CTRL ESC DATA Control information such as sender/receiver/seq. number/etc... (see Flow Control and MAC sub-layer) Control information such as sender/receiver/seq. number/etc... (see Flow Control and MAC sub-layer)
77. Putting it all together… CRC ESC DATA CRC checksum or other error-control information CTRL
115. The MAC sub-layer Data-Link Layer provides packet send/receive service to Network Layer
116. The MAC sub-layer Physical Layer provides binary send/receive to Data-Link Layer
117. The MAC sub-layer But, different media have different constraints about multiple nodes accessing the medium
118.
119. The MAC sub-layer MAC layer provides medium-access service to the Data-Link layer A separate protocol is needed to implement the service for each different transmission medium