In a Token Ring network, what is the primary use of a Multistation Access Unit (MAU)?

Introduction / Context:
Token Ring networks use a logical ring topology to pass a token between stations, controlling which station can transmit at any time. However, the physical cabling in many Token Ring installations does not form a simple loop from workstation to workstation. Instead, a central device known as a Multistation Access Unit is used. Understanding what this device does and why it is needed is a common topic in networking exam questions.

Given Data / Assumptions:

• The network type is IEEE 802.5 or IBM Token Ring.
• The device in question is the Multistation Access Unit, abbreviated MAU.
• The token must circulate from station to station to control access to the medium.
• The question asks for the primary use or purpose of the MAU.

Concept / Approach:
In Token Ring networks, the MAU is a central hub like device. Workstations are connected to the MAU using lobe cables, creating a star shaped physical layout. Inside the MAU, the ports are interconnected to form a logical ring so that the token passes from one station to the next. The MAU also contains bypass relays or similar mechanisms that can remove a faulty or powered off station from the logical ring to maintain network integrity. Therefore, its primary use is to act as a concentrator that physically centralizes wiring while maintaining the logical ring structure required for token passing.

Step-by-Step Solution:
Step 1: Recall that Token Ring requires a logical ring over which the token circulates.Step 2: Recognize that instead of daisy chaining workstations directly in a ring, many networks run individual cables from each station to a central device.Step 3: Understand that the MAU is this central device and that it internally connects ports to form the logical ring.Step 4: Note that the MAU simplifies cabling, makes troubleshooting easier, and can isolate faulty stations using internal relays.Step 5: Conclude that the primary use of the MAU is as a central wiring concentrator that preserves the logical ring for token passing.

Verification / Alternative check:
Diagrams of Token Ring networks in textbooks show a MAU in the center with multiple workstations connected to it in a star configuration. The internal circuitry of the MAU routes the token around the ports. Vendor documentation for Token Ring hubs describes features such as port bypass and ring management, reinforcing the idea that the MAU is a specialized concentrator for forming and maintaining the ring. These references confirm the described primary use.

Why Other Options Are Wrong:
Option B is incorrect because routing IP packets between subnets is the job of routers at the network layer, not of Token Ring MAUs. Option C is wrong because firewalls are designed to inspect and filter traffic, a security function that is different from simple ring formation and wiring concentration. Option D is incorrect because converting analog telephone signals into digital form is the role of voice gateways or adapters, not a Token Ring MAU.

Common Pitfalls:
Students sometimes assume that any central device that looks like a hub or switch performs routing or firewall functions. In reality, a Multistation Access Unit is much simpler and is specialized for Token Ring topology. Another pitfall is to assume that Token Ring always uses a pure physical ring; understanding that the physical layer can be star wired while the logical layer is ring based helps make sense of the MAU design.

Final Answer:
In a Token Ring network, a MAU is primarily used to act as a central wiring concentrator that connects multiple stations in a star wired layout while forming a logical ring for token passing.