Encapsulation and Decapsulation Flashcards
(18 cards)
Encapsulation
Process of adding headers (and sometimes footers) as data moves down the OSI layers.
Decapsulation
Process of removing headers and processing data as it moves up the OSI layers.
Application Layer (OSI)
Generates data (e.g., HTML, HTTP); this is the payload.
Presentation Layer (OSI)
Formats, compresses, or encrypts the data.
Session Layer (OSI)
Manages sessions and maintains connection parameters.
Transport Layer (OSI)
Adds transport header (e.g., TCP/UDP) - data becomes a segment.
Adds transport header (e.g., TCP/UDP) - data becomes a segment.
Adds IP header - data becomes a packet.
Data Link Layer (OSI)
Adds MAC addresses and frame header/trailer - data becomes a frame.
Q: Physical Layer (OSI)
A: Converts the frame into bits and sends it over the media.
Segment
A: The data unit at the Transport Layer.
Packet
A: The data unit at the Network Layer.
Frame
A: The data unit at the Data Link Layer.
Q: Bit
A: The data unit at the Physical Layer.
Q: PDU (Protocol Data Unit)
A: The formatted data unit at each OSI layer.
Q: SDU (Service Data Unit)
A: Data handed down from the layer above to the next layer.
BPDU
A: Bridge Protocol Data Unit, used in Spanning Tree Protocol at Layer 2.
Q: Encapsulation Analogy
A: Like Russian nesting dolls or onion layers - each layer wraps the one above.
Decapsulation Analogy
A: Unwrapping the nesting dolls - each layer removes and processes its header.
