OSI Model (TCP Model Ports/Protocol) Flashcards
What does OSI stand for and name 2 facts, on witch mode do networks operate today?
open systems interconnect model
developed 1977 international organization for standardization
its a reference model (used to categorize the functions of a network, useful for troubleshooting)
under the TCP/IP mode
Name the acronym to list all OSI Layers in the correct order beginning with layer 1
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physical layer 1
data link layer 2
network layer 3
transport layer 4
session layer 5
presentation layer 6
application layer 7
What are networks designed to?
to make data flow across networks
Name the acronmy for data flows through the OSI model
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Data 5 - 7
Segments Layer 4
Packets Layer 3
Frames Layer 2
Bits Layer 1
Name the Physical Layer Overview (2 points) and the Transition Modulation 1 point
first layer transmission of bits across the network occurs and includes physical and electrical network characteristics
Data type occurs as bits (binary bits represented as a serios of 1s and 0s)
transition moulation switching between levels to represent 1 or 0 (copper wire (cat 5/cat 6 - uses voltage 0V or +5/-5V, fiber optic cable - uses light on for 1 off for 0)
What are Layer 1 Connector Standards 4 points
RJ-45 connector - used in cat5/6 cables
wiring standards (TIA/EIA-568A, TIA/EIA-568B)
Crossover cables - TIA/EIA 568A on one end and B on the other end
Straight-through cables - TIA/EIA568B both sides
Name 6 different physical network toplogy layouts of layer 1
Bus, Ring, Star, Hub-and Spoke, Full Mesh, Partial Mesh
based on how cables are physically connected
Name and describe the two synchronization types of layer 1
Asychronous Communication (start and stop bits for out-of-sync data transmission
Synchronous Communication (real-time communication using a common time source)
Name 2 types of bandwitdth utilization of layer 1
Broadband (divides bandwith into spereate channels, cable TV
Baseband (uses all frequency of the cable all the time, telephone
What is multiplexing in layer 1 and name 3 types
involves taking some limited amount of resoucre and using it more efficiently (allows multiple people to use baseband connection same time)
Time Division Multiplexing (TDM) allocates dedicated time slots
Statistical Time Division Multiplexing (StatTDM) dynamically allocates time slots based on when people need it
Frequency Division Multiplexing(FDM) divides the medium into channels
Name 3 Layer 1 Devices and 2 layer 1 device characteristics
Cables - media (fiber optic, ethernet, coaxial)
Wireless Media (bluetooth,wifi, near field communication)
Inftrastructure Devices (hubs, access points, media converters)
simply repeat whatever they receive
no logic or decision-making at layer 1
What does layer 2 (Data Link Layer) do?
responsible for packaging bits from layer 1 into frames and transmitting them across the network
perform error detection and correction, identifies devices using MAC addresses and provides flow control
What does MAC (layer 2) stand for?
Media Access Control Address
Describe Mac (L2) in 3 points
a means for identifiying a device physically and allowing it to operate on a logical topology
a unique 48 bit physical addressing systsem is assigned to everey network interface card (NIC) produced (written in hexadecimal, first 24 bits - identify manufacturer, remaining 24 - identify the specific device
curcial for logical topology - identifying devices on the network
What is Logical Link Control (LLC) in Layer 2 3 points
provides connection services and acknowledges message receipt, ensuring controlled data flow
most basic form of flow control (limits data sent by a sender prevents receiver overwhelm
uses a cheksum to detect corrupted data frames
Name 3 Synchronization Methods at Layer 2
ischronous mode (common reference clock, time slots for transmissions, less overhead)
synchronous method (devices use the same clock, with beginning and ending frames, control characters for sync
asynchronous (devices reference own clock cycles, no strict control over communication timing
Name 3 Layer 2 devices and list operation to one of them
network interface cards (NICs)
bridges
switches (intelligent use of logic to learn and send data to specific devices based on mac addresses
switch operation (switches can use content addressable memory tables (CAM) with MAC addresses to identify physical ports connected to devices, enables selective data transmission to specific areas in network)
What is Network Layer 3 and Logical Addressing
concerned with routing and forwarding traffic using logical addresses
logical addressing (IP variants - common logical addressing schemes IPv4 - written in dotted octet notation which are four sets of numbers (172.16.254.1), IPv6
other protocols - replaced by ip (AppleTalk, IPX internetwork packet exchange)
Name 3 layer 3 switching/routing methods
packet switching (routing) (data is divided into packets and then forwarded, most commonly used method)
circuit switching (a dedicated communicationn link is established between two devices
message switching (data is divided into messages which may be stored and then forwarded)
2 points of route discorvery and selection on layer 3
routers maintain routing tables for determining the best path (dynamic protocols (RIP Routing Information Protocol, OSPF Open Shortest Path First) enable routers to share and update route information
routing protocols help decide how data is going to flow across the network and how routers are going to communicate that information)
Name 3 Connection Services at Layer 3
augments layer 2 services
involves flow control (prevents sender from overwhelming receiver)
packt reordering (ensures data packets arrive and are reassambled in the correct order)