Network Models Ch 1 Flashcards
Layer 1
Physical
Anything that moves data from once system to another system
Does not care about the data it moves
Cabling and Central Box and Hub
Copper, Fiber, Ethernet, Radio Waves
NIC (also part of Layer 2 Data link)
Layer 2
Data - Link
Identifies devices on physical layer
Any device that deals with a MAC address
Switch and NIC
NIC Creates, sends, as well as receives, and reads, Frames
Transfers data in frames between nodes on a network segment across the physical layer.
Layer 3
Network
Network layer provides the means of transferring network packets from a source to a destination host via one or more networks.
Routers assign IP address to send and Receive Packets
Layer 4
Transport
Breaks data down into manageable chunks with TCP
UDP also operates at this layer
TCP Segments
Ports
Layer 5
Session
Manages connections between machines
Provides the mechanism for opening, closing and managing a session between end-user application processes
Sockets operate at this layer
Example: Web browser connection to a web server
Layer 6
Presentation
Translates data from lower levels into format usable by the application layer and vice-versa
Manages data encryption
Data Compression
Layer 7
Application
Provides tools for programs to access the network and lower layers
Does not refer to the application themselves, refers to the code built into the all OS’s that enables network aware applications
API (Application Programming Interfaces)
Example
SSL/TLS
FTP
SNTP
DNS
DHCP
IMAP
HTTP(S)
What is the difference between the OSI and TC/IP models?
TCP IP model consists of only 4 Layers:
Application
Transport
Network
Network Access Layer/Network Interface
Application Application
Presentation Application
Session Application
Transport Transport
Network Network
Data Link Network Interface
Physical Network Interface
Frame
Encapsulates data to transfer across network. Does not move out of a LAN
Part of Layer 2
Frame Model
Preamble | Recipient MAC | Sender MAC | Type- Data | Pad| FCS (Frame Check Sequence)
Type-sums up data in frame
Data - Minimum 64 bytes of data
Pad - Extra Data to bring it up to minimum data
FCS - Error Checking and makes sure all data is sent
Define TCP
Transmission Control Protocol
Packet
Packets get created and addressed so they can go from one network from another
Part of Layer 3
IP piece of data makes sure data gets to where it needs to go on the network
Packet Model
Destination IP| Source IP | Data
MAC
Media Access Control
Known as Physical Address
IP Address
IP (Internet Protocol)
Known as logical address
4 8 bit numbers
each 8 bit ranges from 0-255
0.0.0.0
Define Segment and what Layer its part of
Data that has been broken up into chucks called segments to be transferred across the network.
Part of Layer 4
TCP Segment Model
Source Port | Destination Port | Sequence Number | Acknowledgment (ACK) Number | STUFF | Data
What makes up UDP Data Gram?
Part of Layer 4
UDP Data Gram Model
Source Port | Destination Port | Length | Checksum | Data
Checksum - Simple error detection method that adds numerical value to each packet, allows receiver to detect corruption as it moves the rough network.
