Why segment with a bridge? What are two primary purposes for network segmentation using a bridge (or a modern Layer 2 switch)?

Introduction / Context:
Bridges and modern Layer 2 switches segment LANs into smaller collision domains. By forwarding frames based on MAC addresses and learning, they reduce collisions and increase effective bandwidth. However, they do not break broadcast domains unless VLANs or Layer 3 boundaries are introduced.

Given Data / Assumptions:

• (1) Add more broadcast domains.
• (2) Create more collision domains.
• (3) Add more bandwidth for users.
• (4) Allow more broadcasts for users.

Concept / Approach:

Each switch port is its own collision domain, eliminating collisions seen with hubs. This segmentation means fewer devices contend for the same medium, raising per-user throughput—effectively more bandwidth. Broadcast domains are not changed by simple bridging; broadcasts still flood all ports in the same VLAN or bridge group.

Step-by-Step Solution:

Verification / Alternative check:

Measuring throughput before and after replacing a hub with a switch shows reduced collisions and higher goodput; broadcast volume remains similar unless VLANs are configured.

Why Other Options Are Wrong:

• (1 only) and (4 only) misunderstand broadcast-domain behavior.
• (2 and 4) claims more broadcasts, which is not an intended outcome.
• (1 and 2) mixes a false claim with a true one.

Common Pitfalls:

• Assuming switches reduce broadcasts by default; VLANs or routers are needed to contain broadcasts.
• Overlooking duplex mismatches when migrating from hubs.

Final Answer:

2 and 3 (Create more collision domains; Add more bandwidth for users)