Encapsulation in layered networking Which option best describes encapsulation as used by layered protocols during data transmission?

Introduction / Context:
Encapsulation is the fundamental mechanism that enables layered network models (such as OSI or TCP/IP) to work. Each layer provides services to the layer above by wrapping its data with appropriate headers (and sometimes trailers), producing a new protocol data unit for transmission across the next lower layer.

Given Data / Assumptions:

• We are discussing general, layer-to-layer interactions.
• The lower layer provides a service interface to the higher layer.
• Headers/trailers are added at each step to convey control information.

Concept / Approach:
Encapsulation occurs when, for example, TCP hands a segment to IP, which places the TCP segment into the payload of an IP packet; IP then hands that to Ethernet, which places the IP packet into the payload of an Ethernet frame. This “wrapping” is how addressing, reliability, and physical delivery are layered and kept modular.

Step-by-Step Solution:
Identify the higher-layer data unit (e.g., application payload or TCP segment).Lower layer adds its header/trailer, creating a new PDU.Repeat down the stack until the physical layer transmits bits on the medium.At the receiver, decapsulation removes headers in reverse order.

Verification / Alternative check:
Protocol analyzers (e.g., Wireshark) display nested headers, visually confirming encapsulation: Ethernet > IP > TCP > application data.

Why Other Options Are Wrong:
Best-effort loop avoidance: relates to TTL/hop-limit, not encapsulation.IP fragmentation: creates smaller datagrams; still not the definition of encapsulation.“All of the above”: incorrect because only one statement defines encapsulation.

Common Pitfalls:

• Confusing encapsulation with tunneling; tunneling encapsulates entire packets inside another protocol but is a specific use-case.
• Equating fragmentation with encapsulation; they solve different problems.
• Forgetting trailers (e.g., FCS) also participate at some layers.

Final Answer:
A process where a lower-layer protocol takes a higher-layer message and places it into the data field of its own frame