10. Explain the random-access protocols under the multiple access taxonomy. [10]

Random-access protocols, also known as contention-based protocols, are a type of multiple access protocol where each node has equal access to the transmission medium. These protocols are used in networks where the number of nodes or the amount of data being transmitted can vary significantly. Here are the main types of random-access protocols:

1. ALOHA: This is the simplest type of random-access protocol. In ALOHA, a node sends data whenever it has data to send. If the data packet collides with another packet, the node waits for a random amount of time and then tries again.

2. Slotted ALOHA: This is a variation of ALOHA where time is divided into slots and a node can only send data at the beginning of a time slot. This reduces the chance of collisions but also reduces the throughput.

3. Carrier Sense Multiple Access (CSMA): In CSMA, a node listens to the medium before transmitting. If the medium is busy, the node waits until it is free before transmitting. This reduces the chance of collisions but can lead to a problem known as the "hidden node problem".

4. CSMA with Collision Detection (CSMA/CD): This is a variation of CSMA where a node listens to the medium while it is transmitting. If it detects a collision, it stops transmitting immediately, waits for a random amount of time, and then tries again. This is used in Ethernet networks.

5. CSMA with Collision Avoidance (CSMA/CA): This is another variation of CSMA used in wireless networks. In CSMA/CA, a node sends a short "ready to send" message before transmitting data. If no other node responds with a "clear to send" message, the node begins transmitting.

6. Demand Assigned Multiple Access (DAMA): In DAMA, a central controller assigns transmission slots to nodes based on demand. This is used in satellite networks.

7. Reservation ALOHA (R-ALOHA): In R-ALOHA, nodes reserve future time slots for transmission. This is used in satellite networks.

8. Bit-Map Protocol: In this protocol, a node announces its intention to send a packet in a reservation slot. If more than one node tries to reserve the same slot, a collision occurs and the nodes must try again.

9. Binary Countdown: In this protocol, nodes with data to send broadcast their addresses. The node with the lowest address wins the contention and gets to transmit.

10. Distributed Queue Dual Bus (DQDB): In DQDB, nodes maintain a distributed queue of packets to be transmitted. Nodes can only transmit when they reach the front of the queue.

Each of these protocols has its own advantages and disadvantages, and the choice of protocol depends on the specific requirements of the network.