1.1 Compare and contrast the Open Systems Interconnection (OSI) model layers and encapsulation concepts Flashcards
What is data encapsulation within the OSI model?
Process of adding headers and trailers around some data.
What is data decapsulation within the OSI model?
Is the reverse process of encapsulation. It involves removing the headers and trailers as data moves up the layers of the OSI model until the application layer receives the original data.
What is the Ethernet header?
The Ethernet header is part of the data link layer
destination source MAC
EtherType field
which indicates the protocol of the encapsulated payload.
What is the Internet Protocol (IP) header?
contains information necessary for routing and delivering packets,
such as source and destination IP addresses version
header length
time-to-live (TTL).
What are Transmission Control Protocol (TCP)?
source and destination port numbers
sequence number,
acknowledgment number,
flags,
window size
checksum
What are User Datagram Protocol (UDP) headers?
UDP Header: Contains fields like source and destination port numbers, length, and checksum.
What is the payload in data encapsulation?
The payload is the actual data being transmitted, which is encapsulated within the headers of various protocols at different layers of the OSI model.
What are TCP flags?
TCP flags are control bits used to manage the state of a connection. Common flags include:
SYN (Synchronize)
ACK (Acknowledgment)
FIN (Finish)
RST (Reset)
PSH (Push)
URG (Urgent)
What is Layer 1 of the OSI model?
Physical:
Physical connection between devices
cables
fiber
signal
What is Layer 2 of the OSI model?
Data Link Layer
Responsible for node-to-node data transfer, error detection, and correction.
MAC addresses
Switches
Hubs
Frames
What is Layer 3 of the OSI model?
Network Layer
Handles routing of data packets via IP addresses.
Fragments frames for travel to different networks
Routers
Fire Wall
Packets
What is Layer 4 of the OSI model?
Layer 4 – Transport:
“Post Office Layer”
Deals with port numbers
Ensures complete data transfer and error recovery.
Includes:
TCP and UDP
What is Layer 5 of the OSI model?
Layer 5 – Session:
Start, Stop, and Restart
Tunnel
Manages connections between applications.
It handles setup, coordination, and termination of sessions.
What is Layer 6 of the OSI model?
Layer 6 – Presentation:
Character Encoding Encryption
Decryption
SSL/TLS
Insures data is in a usable format
What is Layer 7 of the OSI model?
Layer 7 – Application:
The Layer that we see
HTTP
FTP
SMTP
Provides network services directly to applications.
