LAN bridges and interoperability: Because bridges are store-and-forward (they buffer complete frames before forwarding), is it possible to interconnect different LAN segments that use different MAC protocols (for example, Ethernet and Token Ring) using an appropriate translational bridge?

Introduction:
Bridges are classic Layer 2 devices that receive entire frames, buffer them, and then forward them based on MAC addresses. A frequent question in exams is whether buffering alone enables interoperability across different LAN types. The nuanced answer is that translational bridges can, in fact, connect different MAC protocols (for example, Ethernet to Token Ring) by translating framing details, while still performing the store-and-forward action typical of bridges.

Given Data / Assumptions:

• Bridge operates in store-and-forward mode (buffers frames).
• Different LAN segments may use different MAC/PHY conventions (e.g., frame formats, bit order, MTU).
• The question asks if interconnection is possible using suitable bridging.

Concept / Approach:
A standard transparent bridge connects like-technology LANs (e.g., Ethernet to Ethernet). A translational bridge, however, implements protocol translation between dissimilar MACs while still forwarding at Layer 2. Because a translational bridge buffers and rewrites frames, it can map fields, adjust addresses/lengths, and handle differences in framing conventions so end stations can communicate across heterogeneous LANs without a Layer 3 router.

Step-by-Step Solution:
1) Identify that a bridge buffers frames → store-and-forward behavior.2) Recognize two categories: transparent bridges (same MAC type) and translational bridges (different MAC types).3) Understand that translational bridges modify MAC-level encapsulation while preserving payloads.4) Conclude: with the appropriate translational bridge, different MAC LANs can be interconnected.

Verification / Alternative check:
Historical implementations (e.g., Ethernet–Token Ring translational bridges) are well-documented in enterprise networks and standards guidance. They preserve Layer 3 transparency while adapting Layer 2 framing differences.

Why Other Options Are Wrong:

• Incorrect: Dismisses the existence of translational bridges.
• Only possible with routers: Routers operate at Layer 3 and are not required when a translational bridge suffices.
• Applies only to identical Ethernet segments: True for transparent bridges, but the question concerns whether it is possible across different MACs.
• Not applicable in IEEE 802 networks: Misleading; translational bridging has been used within IEEE 802 environments.

Common Pitfalls:
Equating all bridges with “same-MAC only” behavior; forgetting that translational bridging exists to span dissimilar MACs without moving up to routing.

Final Answer:
Correct