Note: We skipped the slides on multicast last lecture.

Link layer #

Link layer services #

MAC = media access control, MAC addresses are 48 bits.

Where the link layer is implemented #

rdt = reliable data transfer

Error detection/correction #

$G$ can be any sequence as long as the sender and receiver use the same sequence.

So if we pad the right side of $D$ with $R = 011$ , we will get a remainder of $0$ when the receiver performs the division.

Multiple access protocols #

CSMA/CD is used by ethernet, CSMA/CA is used by wifi.

On axis: C = collision, E = empty, S = successful

If we have $N$ nodes, for a given node in slotted ALOHA, the probability is $Np(1 - p)(1-p)(1-p) \cdots (1-p)$ .

Success = $Np(1-p)^{N-1}$ .

CSMA is still a random access protocol.