OSI Networking Model Flashcards
How does the OSI model differ from the TCP/IP model?
What is the function of the Physical layer of the OSI model? What is the corresponding layer in the TCP/IP model?
How does the Presentation layer ensure that data presented to the Application layer is in a compatible form?
Which protocols are used by the Data Link layer?
How are host-to-host connections managed?
Which protocols are used to determine the IP address of a known MAC address?
What is Secure Sockets Layer (SSL)
SSL is a data encrypting technology
What is Simple Mail Transport Protocol (SMTP)
SMTP is an email relay protocol
Trivial File Transfer Protocol (TFTP)
TFTP is a file transferring protocol that uses UDP
What is Secure Shell (SSH)
SSH is a remote device connectivity protocol
What is Simple Network Management Protocol (SNMP)
SNMP is a management and troubleshooting protocol
In the OSI model what does the presentation layer do?
Formats data
What does the session layer in the OSI model do?
Session Management - To keep track of sessions on particular systems
What is the OSI model and what does it do?
classifies and organizes the tasks that hosts perform to prepare data for transport across the network.
What are the reasons the OSI model is useful for?
Provides a common language or reference point between network professionals.
Divides networking tasks into logical layers for easier comprehension.
Allows specialization of features at different levels.
Aids in troubleshooting.
Promotes standards and interoperability between networks and devices.
Provides modularity in networking features. Developers can change features without changing the entire approach.
List the limitations of the OSI model
OSI layers are theoretical and do not actually perform real functions.
Industry implementations rarely have a layer-to-layer correspondence with the OSI layers.
Different protocols within the stack perform different functions that help send or receive the overall message.
A particular protocol implementation may not represent every OSI layer, or may spread across multiple layers.
Describe the Application layer in the OSI model
integrates network functionality into the host operating system and enables network services.
List the services of the application Layer
Interface- provides an interface for a service to operate
Communication - enables communication partner identification
File Services - transferring, storing, and updating data
Print Services - enabling network printers to be shared by multiple users.
Message services–transferring data in many formats (text, audio, video) from one location to another or from one user to another.
Application services–sharing application processing throughout the network and enabling specialized network servers to perform processing tasks.
Database services–storing, retrieving, and coordinating database information throughout the network.
What does the presentation layer do in the OSI model?
formats or presents data into a compatible form for receipt by the Application layer or the destination system.
List some of the things the Presentation layer does
Formatting and translation of data between systems.
Negotiation of data transfer syntax between systems by converting character sets to the correct format.
Compatibility with the host.
Encapsulation of data into message envelopes through encryption and compression.
Restoration of data through decryption and decompression.
List some of the protocols of the presentation layer
PEG, BMP, TIFF, PICT
MPEG, WMV, AVI
ASCII, EBCDIC
MIDI, WAV
Describe the Session Layer of the OSI model
managing the sessions in which data is transferred.
Name some of the functions of the Session layer
Keeps data streams separate (session identification).
Sets up, maintains, and tears down communication sessions.
Establishment and maintenance of communication sessions between the network hosts, ensuring that data is transported.
Management of multiple sessions (each client connection is called a session). A server can maintain thousands of sessions simultaneously.
Assignment of the session ID number to each session, which is then used by the Transport layer to properly route the messages.
Dialog control that specifies how the network devices coordinate with each other (simplex, half-duplex, and full-duplex).
Termination of communication sessions between network hosts after completion of the data transfer.
Coordination of requests and responses between different hosts using the same application.
Name some of the protocols on the session layer
Network File System (NFS) Apple Session Protocol (ASP) Structured Query Language (SQL) Remote procedure call (RPC) X Window
Describe the Transport Layer
Enables end to end flow control
Uses port numbers to identify apps running on the same system
Receives Large packets and breaks them down into segments
What two protocols work on the Transport layer?
TCP and UDP
Name some the functions of the network layer
Defines logical addresses (host and network).
Uses path determination (identification and selection).
Routes packets.
Describes how data is routed across networks and to the destination.
Maintains addresses of neighboring routers.
Maintains a list of known networks.
Determines the next network point to which data should be sent. Routers use a routing protocol to take into account various factors, such as the number of hops in the path, link speed, and link reliability to select the optimal path for data.
What protocols work on the Network Layer
IP
AppleTalk
List functions of the data link layer
Converts bits into bytes and bytes into frames.
Uses MAC address (also called the burned in address or hardware address).
Defines the logical network topology.
Specifies media access methods.
Implements host-to-host flow control.
Uses parity and CRC.
What is the Logical Link Control layer?
provides an interface between the MAC layer and upper-layer protocols.
What is the Logical Link Control layer responsible for?
Maintaining orderly delivery of frames through sequencing.
Controlling the flow or rate of transmissions using:
Acknowledgements
Buffering
Windowing
Ensuring error-free reception of messages by retransmitting.
Converting data into an acceptable form for the upper layers.
Removing framing information from the packet and forwarding the message to the Network layer.
Providing a way for upper layers of the OSI model to use any MAC layer protocol.
Defining Service Access Points (SAPs) by tracking and managing different protocols.
What protocols are on the Logical Link Control layer?
LAN protocols:
802.2 (LLC), 802.3 (Ethernet
802.11 (Wireless)
WAN protocols:
PPP
MLPPP
ISDN
Define the Media Access Control (MAC) layer
defines specifications for controlling access to the media.
What are some of the functions of the MAC layer?
Adding frame start and stop information to the packet.
Adding Cyclical Redundancy Check (CRC) for error checking.
Converting frames into bits to be sent across the network.
Identifying network devices and network topologies in preparation for media transmission.
Defining an address (such as the MAC address) for each physical device on the network.
Controlling access to the transmission medium.
Define the Physical Layer of the OSI model
All of the physical connections in a network
List functions of the Physical Layer of the OSI model
Moves bits across the media.
Defines cables, connectors, and pin positions.
Specifies electrical signals (voltage, bit synchronization).
Defines the physical topology (network layout).
Sets standards for sending and receiving electrical signals between devices. It describes how digital data (bits) are converted to electric pulses, radio waves, or pulses of lights. Devices that operate at the physical layer send and receive a stream of bits.
What protocols work on the physical layer
EIA/TIA 232 (serial signaling)
V.35 (modem signaling)
Cat6
RJ45
Define Trivial File Transfer Protocol (TFTP)
lets you transfer files between a host and an FTP server. However, it provides no user authentication and uses UDP instead of TCP as the transport protocol.
What layers does TFTP work on?
Application, Presentation and session layers
What layers does SMPT work on?
Application and Process layers
What layer does SNMP work on
Application/Process layer
What layers does Remote Terminal Emulation (Telnet) work on?
Application, Presentation , Session
Define Address Resolution Protocol
ARP is used to get the MAC address of a host from a known IP address. ARP is used within a subnet to get the MAC address of a device on the same subnet as the requesting device.
What layer does ARP work on?
Network layer
Define Reverse Address Resolution Protocol (RARP)
used to discover the IP address of a device with a known MAC address. BOOTP is an enhancement to RARP and is more commonly implemented than RARP
Define Bootstrap Protocol (BOOTP)
used by computers as they boot to receive an IP address from a BOOTP server. The BOOTP address request packet sent by the host is answered by the server.
What layer does DHCP work on
Network layer
Define Open Shortest Path First (OSPF) protocol
a route discovery protocol that uses the link-state method. It is more efficient than RIP in updating routing tables, especially on large networks.
What layer does Open Shortest Route (OSPF) work on
Network layer
Define Routing Information Protocol (RIP)
RIP is a route discovery protocol that uses the distance-vector method. If the network is large and complex, OSPF should be used instead of RIP
What layer does Routing Information Protocol (RIP) work on?
Network Layer
