Fundamentals of Multiprocessor Interconnection Networks Quiz

Explore essential concepts of multiprocessor interconnection networks with this quiz, covering topologies, routing, scalability, and types of communication links. Gain insights into network designs and how multiprocessor systems enable efficient parallel computing through effective communication structures.

1. Basic Definition

   What is the primary function of an interconnection network in a multiprocessor system?

   1. It ensures only one processor is used at a time.
   2. It connects processors and memory modules to enable data transfer.
   3. It formats data before storage on hard drives.
   4. It increases processor speed by doubling the clock rate.

   Explanation: The core function of an interconnection network is to facilitate data transfer between processors and memory in multiprocessor systems, enabling parallel operation. Increasing processor speed (option B) is not the network's job. Formatting data for storage (option C) is unrelated to network connectivity. Ensuring only one processor operates (option D) contradicts the purpose of multiprocessors, which utilize multiple CPUs simultaneously.

2. Types of Topologies

   Which topology connects each processor directly to every other processor, forming a complete graph?

   1. Ring
   2. Fully-connected
   3. Linear bus
   4. Mesh

   Explanation: A fully-connected topology links each processor directly to every other, resulting in the maximum number of possible connections. A linear bus (option B) uses a shared communication line, not direct links. A ring (option C) connects nodes in a closed loop, while a mesh (option D) has connections only between nearby nodes rather than all possible pairs.

3. Direct vs Indirect Networks

   Which statement best describes a direct interconnection network in multiprocessor systems?

   1. Data can only be exchanged serially, one bit at a time.
   2. Each processor communicates with all others through a single central switch.
   3. Processors do not communicate but only access shared disks.
   4. Each processor is connected only to a subset of other processors, usually nearby ones.

   Explanation: Direct networks use point-to-point links between subsets of processors, forming regular patterns like meshes or rings. Option B instead describes an indirect or centralized network. Option C incorrectly claims no communication occurs. Option D references serial transmission, which is not unique to network type.

4. Scalability

   Which feature makes the mesh topology especially favorable for scalable multiprocessor systems?

   1. It automatically doubles processor speed with each new addition.
   2. It requires each processor to have a direct link to all others.
   3. It relies on a central controller, limiting expansion.
   4. It allows the network size to grow easily by adding rows and columns.

   Explanation: A mesh topology enables scalable growth by expanding in two dimensions, facilitating the addition of more nodes without major redesign. Direct links between all processors (option B) describe a fully-connected network, not a mesh. Central controller dependence (option C) actually restricts scalability. Option D misinterprets network growth; processor speed is not inherently doubled.

5. Routing Techniques

   What method is typically used in multiprocessor networks to determine the path taken by a data packet from source to destination?

   1. Routing algorithm
   2. Simple broadcasting
   3. Address arithmetic
   4. Data compression

   Explanation: A routing algorithm is responsible for computing appropriate paths for data packets across network nodes, ensuring communication efficiency and avoiding congestion. Address arithmetic (option B) concerns memory addressing, not network pathfinding. Data compression (option C) reduces data size but does not influence paths. Simple broadcasting (option D) sends data to all nodes, which is inefficient for targeted communication.

6. Performance Bottlenecks

   In a shared bus-based multiprocessor system, what typically limits the overall communication performance as the number of processors increases?

   1. Direct links between all processors enable infinite bandwidth.
   2. Ring topologies cause constant transmission delays.
   3. Processors become slower with more memory modules.
   4. Bus contention makes simultaneous access slower.

   Explanation: As more processors attempt to use the same shared bus, contention increases, slowing overall communication. Adding memory modules (option B) does not inherently slow processors in a bus-based context. Ring topology issues (option C) are not relevant here. Direct links between all processors (option D) do not apply to shared bus systems and do not provide infinite bandwidth.

7. Switching Mechanisms

   Which switching technique in an interconnection network allows multiple packets to be forwarded simultaneously through different paths, improving throughput?

   1. Manual switching
   2. Disk switching
   3. Packet switching
   4. Single-path switching

   Explanation: Packet switching enables the division of data into smaller packets that can travel independently through the network, allowing simultaneous transmissions and improved efficiency. Single-path switching (option B) limits transmission to one path, reducing throughput. Disk switching (option C) is unrelated to network communication. Manual switching (option D) does not refer to automated network operations.

8. Examples of Network Types

   Which of the following is an example of an indirect interconnection network for multiprocessor systems?

   1. Fully-connected network
   2. 2D Mesh network
   3. Linear ring network
   4. Multistage network (like Omega or Butterfly)

   Explanation: Multistage networks, such as Omega or Butterfly, route messages through intermediate switches or stages, making them indirect. Fully-connected, mesh, and ring networks (options B, C, and D) are direct, as they do not use intermediary stages between source and destination.

9. Advantages of Ring Topology

   What is a major potential advantage of using a ring topology for connecting processors in a multiprocessor system?

   1. It provides direct low-latency paths to all processors.
   2. It guarantees zero failures in data transmission.
   3. It uses fewer links per processor compared to a fully-connected network.
   4. It eliminates the need for data routing altogether.

   Explanation: A ring topology connects each processor to only two neighbors, drastically reducing the number of required links as compared to a fully-connected network. Option B is incorrect as not all processors are reached directly. Option C misrepresents network function, since some data routing is always necessary. Zero failures (option D) cannot be guaranteed by any topology.

10. Point-to-Point Links

    What is a point-to-point communication link in the context of multiprocessor interconnection networks?

    1. A direct physical connection between two network nodes
    2. A shared pathway used by all processors and memory modules
    3. A wireless broadcast channel covering multiple processors
    4. A data storage device attached to the network

    Explanation: A point-to-point link refers to a dedicated connection between two nodes, allowing direct, targeted communication. Option B describes a shared bus, not point-to-point. Option C refers to wireless broadcast, which is not specific to point-to-point. Data storage devices (option D) are not communication links and fall outside the scope of network structures.