OSI Model
What is the PDU for the Physical layer?
Bits
____ is the Protocol Data Unit for layers 5-7.
Data
The process of taking a piece of network traffic, and adding more information to the beginning (and sometimes the end) to form a new piece of data.
Data Encapsulation
What process occurs when the PDU goes from a bit to a frame?
Decapsulation
When information is going up the stack (layer 1 to layer 7) When we go up, we are removing a header from the data
Decapsulation
When data is "moving up the stack", what process is occurring?
Decapsulation is going up the stack
Once your data has been fully encapsulated and transmitted to the destination, what process occurs to unpack that information?
Decapulation
Network layer 3
Decides which physical path the data will take
Transport layer 4
Decides which physical path the data will take
Datalink layer 2
Defines the format of data on the network
Who was responsible for the development of the TCP/IP Reference Model?
DoD
What is described as the process of taking a piece of data and wrapping it in another type of data?
Encapsulation
When information is going down the stack (layer 7 to layer 1) When we go down, we are adding a header to the data
Encapsulation
Presentation layer 6
Ensures that data is in a usable format and is where data encryption occurs
What hardware are associated with layer 4?
Firewall?
What is the data unit for the Data Link Layer?
Frames
What are the Layer 3 services discussed?
Host addressing and Packet Forwarding/Routing
Application layer 7
Human-computer interaction layer, where applications can access the network service
Antennas Repeaters/Amplifiers Network Adapters Cables Hubs Voltages & Radio frequencies
Layer 1 Hardware
USB belongs to what Layer of the OSI model?
Layer 1 Physical
The Physical Layer (Layer 1) specifies the physical and electrical components, including cables, cards, and any other physical aspects. This layer is where data is moved across the network. Layer 1's data unit is "bit" Layer 1 is responsible for: Transmission and reception of raw data between a device and transmission medium (Ethernet, Wi-Fi, etc) Bit rate control to define transmission mode (Simplex, half-duplex, and full-duplex) Converts the digital bits into electrical, radio, optical signals, and electromagnetic waves This is the most complex layer due to the diversity of available hardware technologies, their characteristics, and how they interact with the above layers.
Layer 1 Physical Layer
Circuit Switching Multiplexing Physical Topologies Bus, Star, Mesh, etc
Layer 1 Services
IEEE 802.3 (Ethernet) DSL USB
Layer 1 Technologies
In which layer, during encapsulation, is a header and trailer added to a packet?
Layer 2 Data Link
What layer of the OSI model is concerned with error detection and flow control, and is split into two sublayers?
Layer 2 Data Link
The Data Link Layer (Layer 2) transfers data between adjacent network nodes in a WAN or between nodes on the same LAN segment. Layer 2's data unit is "frame" Layer 2 is responsible for: Detecting and (sometimes) correcting errors that may occur at the physical layer Defining the protocol to establish and terminate a connection between two connected devices Defining the protocol for flow control between devices Flow control makes it possible for a the recipient of data to tell you how fast/slow you should send data, and vice versa
Layer 2 Data Link Layer
Network cards Switches
Layer 2 Hardware
ATM (Copper telecommunications) IEEE 802.2 (LLC) IEEE 802.3 (Ethernet) IEEE 802.11 (Wi-Fi) HDLC / Frame Relay / MPLS / PPP (WAN Protocols) ARP
Layer 2 Protocol
Media Access Control (MAC) Addresses (Used for MANs, Switches, Physical addressing, etc.)
Layer 2 Services
Routers
Layer 3 Hardware
Which layer uses IP addresses to route data
Layer 3 Network
The Network Layer (Layer 3) provides the means of transferring packets from one source to destination via one or more networks. Layer 3's data unit is a "packet" Layer 3 is responsible for: Forwarding and routing data packets Provide cross-network addresses Construction and updating of routing tables Fragmentation of data packets Fragmentation is when a layer 3 packet is too big to send, so the router splits the message into several pieces. At the destination, these pieces are put back together in order, and the packet is processed normally
Layer 3 Network Layer
IPv4 IPv6 ICMP IGMP IPSec (security protocol) NAT RIP OSPF EIGRP
Layer 3 Protocols
Host addressing Packet Forwarding/Routing
Layer 3 Services
Firewalls
Layer 4 Hardware
TCP (slower, but connection-oriented) UDP (fast and connectionless) Authentication Header (IPsec)
Layer 4 Protocol
Connection-Oriented Communication Flow control/Congestion Avoidance
Layer 4 Services
What layer is responsible for the following: - Controlling how much data is sent, and where it is sent to - Controlling how fast data is sent - Monitoring the state, connection, and success of delivery for certain protocols
Layer 4 Transport
The Transport Layer (Layer 4) manages reliability and quality of traffic. Layer 4's data unit is a "segment". Layer 4 is responsible for: Segmentation/Desegmentation of the data stream Segmentation is when a layer 4 segment is too big to send, so it is split into several pieces. At the destination, these pieces are put back together in order, and the traffic is processed normally Managing Layer 3 traffic flow to reduce congestion Controlling how much data is sent, and where it is sent to Security functionalities (Firewall and some encryption methods) Monitoring the state, connection, and success of delivery for certain protocols Encapsulating packets for transmission up to higher layers The Transport layer gives the above layers a standardized view of data, so that they do not have to be involved in knowing the characteristics of lower level network traffic and how it communicates. This is the highest layer of network communications
Layer 4 Transport Layer
Authentication/Authorization Session Management/Restoration NetBIOS (API for applications)
Layer 5 Services
Which layer establishes, manages, and terminates connections between applications?
Layer 5 Session
Which layer is responsible for the following- Establishing and managing connections between local and remote applications - Providing simplex, half-duplex, or full-duplex operations - Establishing procedures for check-pointing, suspending, restarting, and terminating a connection
Layer 5 Session
The Session Layer (Layer 5) controls the connections between computers, and establishes request/response communication. It also receives service requests from Layer 6 and issues requests to Layer 4 through APIs. Inputs from the user, regarding the session, make a request (Authentication, closing sessions, restoring sessions, etc) This is the first layer discussed that use a client/server concept Layer 5 is responsible for: Establishing and managing connections between local and remote applications Providing simplex, half-duplex, or full-duplex operations Establishing procedures for checkpointing, suspending, restarting, and terminating a session This is done because Layer 5 organizes and synchronizes all data exchanges, allowing for it to be checkpointed Closing and re-opening connections that have not been used in a long period of time This concept is referred to as Layer 5 having a semi-permanent dialogue
Layer 5 Session Layer
Security Protocols belong to which layer of the OSI Model?
Layer 6 Presentation
What layer of the OSI model hosts the security protocols TLS and SSL?
Layer 6 Presentation
What layer of the OSI model primarily deals with technologies such as JPEG and MPEG?
Layer 6 Presentation
Which layer primarily handles encryption/decryption?
Layer 6 Presentation
The Presentation Layer (Layer 6) establishes context between application layer syntax/semantics, taking the information from the application layer of one system and reformatting it to be readable by the application layer of another system. This processes of finding and using a common format requires many tools/responsibilities Layer 6 is responsible for: Handling String Representation This essentially means that Layer 6 can identify data Allows the Application layer to point to data to have it moved, and the Presentation layer will deal with the rest Data Compression Encryption/Decryption Encryption is primarily done here, but can be done at other layers, each having its own advantages and disadvantages
Layer 6 Presentation Layer
TLS/SSL (Security Protocols)
Layer 6 Protocols
Data Encryption/Decryption ASCII MPEG
Layer 6 Services
Which of the layers discussed is responsible for relaying information to the user in order for them to see and interact with it?
Layer 7 Application
The Application Layer (Layer 7) is the "visual layer" It receives input from the user, and displays data in a way they can understand Provides an interface for the end user's device that is connected to a network It is not an application - it represents the components in the application, which controls communication with other nodes Layer 7 is responsible for: Displaying received information to the user (via the interface) Controls the interface methods used in communications across the network
Layer 7 Application Layer
HTTP/HTTPS (Web browsing) Telnet/SSH/RDP (Remote access) FTP/TFTP (File Sharing) TLS/SSL (Security Protocols) DHCP/DNS (Networking Support) POP3/IMAP/SMTP (Email) SNMP/LDAP (Host/Network management)
Layer 7 Protocols
These layers control the interactions and usage with application programs, user display, and allowing access to network resources for end users. There are distinct duties and characteristics of each of these layers in the OSI Model, but some services/protocols apply to more than one of them The data unit (PDU) for all 3 of these layers is "data"
Layers 5-7 Session, Presentation, and Application
Layer 2 Data Link: Responsible for identifying and encapsulating network layer protocols, and controls error checking and frame synchronization Scans for errors
Logical Link Control (LLC)
What are the two sublayers of layer 2?
MAC and LLC
Session layer 5
Maintains connections and is responsible for controlling ports and session
Layer 2 Data Link: Responsible for controlling how devices in a network gain access to a medium (Ethernet, Wi-Fi, etc) and their permission to transmit data Ensures that those who need network access have a way to gain it, by providing it access to your transmission medium How access data and position.
Medium Access Control (MAC)
IEEE Project 802 splits the data link layer into two sublayers:
Medium Access Control (MAC) and Logical Link Control (LLC)
Is a conceptual model used in networking to standardize how nodes and networks communicate from start to finish. The OSI model breaks data transmission into the following 7 layers
OSI Model
The OSI layer 3 Protocol Data unit is referred to as a(n) "____".
Packet
What is the Protocol Data unit (PDU) for layer 3?
Packets
What devices are associated with the Network layer?
Routers
What is the Protocol Data Unit for Layer 4?
Segment
What is one thing that the Transport Layer is responsible for?
Segmentation, Relieving congestion, Managing Traffic Flow.
When data is handed to the Session Layer, a(n) ___ is tagged to the data
Session ID
What is the purpose of standardization?
So that different manufacturers can communicate with each other
Name one of the protocols discussed that operate at Layer 4 of the OSI model?
TCP, UDP, IPsec
The __ model is used to describe how networks connect and properly communicate, rather than how network communication functions from start to finish?
TCP/IP
Why do we use the TCP/IP Model over the OSI Model?
TCP/IP Describes implementation of network OSI Model service and hardware specifically and isn't necessary to know
The TCP/IP Model was developed by DARPA and the DoD, and predates the worldwide, global internet and OSI Model. As the internet grew, this model was released to the public Because of this, it is also referred to as the DoD Model, or the "internet model" The TCP/IP Model defines a suite of protocols that had an end goal of ensuring a connection between a source and destination. The TCP/IP Model is the model that every organization follows today when discussing networking
TCP/IP Model
Is the standard for actual use by network engineers, NOT the OSI model, when building and maintaining network connections.
TCP/IP Model Standard
Email and ATM
Transmission Control Protocol (TCP)
Physical layer 1
Transmits raw bit stream over the physical medium
True or False: The PDUs for the TCP/IP Model are the same as the OSI Model.
True
True or False: The Physical Layer is the most complex OSI layer.
True
True or False: The data link layer is the only layer of the OSI model that applies both a header and a trailer.
True
True or False: The modern TCP/IP Model is 5 layers.
True
Youtube and Twitch Fast not as efficient as TCP Packet loss
User Datagram Protocol (UDP)
How many layers are in the TCP/IP Model?
5 Layers
The OSI Model consists of how many layers?
7
A 5 layer Model that wraps Layers 5-7 of the OSI model into one layer. The layers are as follows from top to bottom: The functions of Layers 1-4 are the same as the OSI Model, with the Application Layer simply being the culmination of Layer 5-7 of the OSI model in terms of services, function, and protocols associated.
Application Transport Network/Internet Data Link Physical
HTTP resides at layer ___ of the OSI model.HTTPS resides at layer ___ of the OSI model (Format: '____, ____')
Application, Application
