Topologies and Protocol Suites (PART 1)

Q1. What types of topologies are commonly used for Local Area Network (LAN) and Wide Area Network (WAN)?

• Bus, ring, star, mesh, tree and cellular topologies are used for LANs; whereas , point-to-point, multipoint, mesh and cloud topologies are used for WANs.

 

Q2. Explain tree topology.

• A tree topology is a LAN architecture that is similar to the bus topology but with multiple nodes. It can also be defined as a combination of the bus and star topologies.

                                       


Q3. What devices are currently used in LAN networks?

•  The commonly used devices in the LAN network are repeaters, hubs, LAN extenders, bridges, LAN switches and routers.

Q4. What is repeater?

• A repeater is a device used to interconnect the media segments of an extended network. It enables a series of cable segments to be treated as a single cable. Repeaters receive signals from one network segment and amplify, retime, and retransmit those signals to another network segment to prevent signal deterioration caused by long cable lengths and large numbers of connected devices. 

Q5. What is hub?

• A hub is a device that connects multiple user stations , each through a dedicated cable.

Q6. Multiple devices cannot communicate on the network simultaneously; therefore, what type of method must be used to allow one device to access network media at a time?

• Carrier Sense Multiple Access/ Collision Detection (CSMA/CD) and token passing

Q7. What is CSMA/CD?

• CSMA/CD is a layer 2 access method in which if a transmission data station detects another signal while transmitting a frame, it stops transmitting the frame. Instead of the frame, it transmits a jam signal, and then waits for a random time interval before trying to send the frame again.

Q8. What is token passing?

• A token is small frame, which is passed from one node to another in a token ring network. If a node has data to send, it must wait until it receives a token. After the token is received by the node, it seizes the token, makes it as used, and attaches the data. The frame is then addressed to the destination node and the node continues passing the data around the ring until it arrives at the destination node. The destination node copies the data and marks the frame as received. When the sender node receives the frame, it implies that the data is successfully delivered. The sender node then frees the token to be used by another node.

Q9. List the reasons of transmission failure?

• Bad cabling
• Improper termination
• Collisions
• Improper cable length