week 1 reading Flashcards
What are the 7 layers?
- Physical
- Datalink
- Network
- Transport
- Session
- Presentation
- Application
“All People Seem To Need Data Processing”
What is data called in the OSI model?
Protocol Data units (PDU)
What is data called in the physical layer?
Bits
What is data called in the datalink layer?
Frames
What is data called in the Network layer?
Packets
What is data called in the transport layer?
Segments
Current State Modulation
The absence/presence of voltage dictates 1s and 0s (note: voltage tries to maintain average of 0)
State transition Modulation
state of change dictates 1s and 0s
What is the physical layer responsible for?
How bits are represented on medium
wiring standards
topology
synchronizing bits
Bandwidth usage
multiplexing strategy
What are the two parts of the data link layer?
MAC (media access control)
LLC (Logic Link control)
What is a MAC address?
unique 48 bit address burned into the Network interface card to uniquely identify your device
Ethernet
Devices on a shared segment check for traffic before transmitting, retransmits if there’s collision
What are the three ways that LLC synchronizes transmissions?
Isynchronous - coordinating through external device’s clock
asychronous - devices look at their own clock
Synchronous - device share clock with each other
What is the MAC sublayer (data-link) responsible for?
Physical addresses, Logical topologies and transmission methods
What is the LLC Sublayer responsible for?
Connection services (flow control & error checking) and Transmission synchronization
What is the Network layer responsible for?
Logical addressing
Switching
Route discovery and selection
Connection services
Packet switching
dividing data into packets, attaching headers and destination address
What does a router do?
Forwards Packets based on logical addresses. Usually found in the Network layer
What does the transport layer contain?
Protocols (TCP/UDP)
Windowing
Buffering
Sliding Window Size
The amount of segments being sent at one time which increases each successful transmission + acknowledgement
Buffering/Queue
Memories to store segments until bandwidth is available at the destination to send more
What does the session layer do?
Setting up a session
Maintaining a session
tearing down a session
What does the presentation layer do?
Data formatting (ascii)
Encryption
What is the application layer?
Services that support applications and let’s applications know that certain services are available to those applications (ie printers
