Networking Models 5 Flashcards
Name the seven layers of the OSI model
All People Seem To Need Data Processing
Application layer Presentation layer Session layer Transport layer Network layer Data link layer Physical layer
The OSI Reference Model is
A network model developed by ISO for communication in open system networks. Divides the data communication process into seven tasks called layers. Each layer is designed to link the layers above it. A layer provides services to the layer above and requests service from the layer below
describe what an open system network is
A network that supports multiple communication protocol suites that different vendors develop
The layers in the OSI reference model can be classified into two functional blocks
Application support : consists of the upper three layers. Application, presentation, session. Primary function is to connect software programs to the network
Network support : consists of the lower four layers. Transport, network, data link, physical. Primary function is moving data on the network
Describe the physical layer 1
Transmits data packets over a physical medium. Determines the mode and medium Od data transmission. Receives fully formatted data packets from the data link layer and places them in the media. Network adapters and WAP are some devices that operate at this layer.
Technologies that operate at this layer are Ethernet, fast Ethernet, token ring, FDDI, ATM Asynchronous Transfer Mode
Describe what a packet is
A unit of data transmitted on a network. All packets contain three parts : header, data, and footer/trailer.
What is a multilayer device
Network devices that can perform tasks on more than one layer and functions actress layers. Ex WAPs, gateways, hubs and repeaters
Describe the data link layer 2
Responsible for grouping data bits into frames and attaching the address of the receiving node to each frame to form the data packet
Error free transfer of data packets between nodes on the network. After transfer waits for acknowledgement from receiving node
Adds error correction and detection codes to frames to perform error checks and corrections.
Devices operating at this layer. Switches.
Protocols operating at this layer. PPP point to point protocols and SLIP serial line Internet protocol
Can be divided into two sub-layers LLC & MAC
LLC sub-layer of data link layer
Responsible for identifying network layer protocols and encapsulating so multiple upper layer protocols can share the same media. Controls how frames are places on the media by controlling the physical layer device. Checks the CRC the frame and either ACKs or NACKs the data
The MAC sub-layer of the data link layer
Defines now packets are placed on the media. In contention based network responsible for detecting collisions for the carrier sense
In token passing network responsible for the token
Describe network acknowledgement
A signal used by communication protocol between nodes on a network to acknowledge the receipt of data ACK positive successful receipt NACK negative bad transmission REJ rejection of data ARQ automatic request for retransmission
Describe the network layer 3
Responsible for addressing data packets, routing packets from a source to the destination through the network and ensuring data delivery. Controls congestion on the network by taking proper routing decisions. Defines protocols for interconnecting two or more similar networks such as IP, ARP, DHCP, ICMP, RIP, BGP, OSPF, IGMP
Routers and switches operate at this layer.
Describe the transport layer 4
Accepts data from upper layers and breaks it into smaller units called segments. Then passes these segments to the lower layers and ensures that all Segments arrive correctly at the receiving end. This layer adds a sequence number to reach segment to help reconstruct the original sequence of segments. Also responsible for error correction and sending ACK at the network level.
Defines protocols for interconnecting networks using difference protocols.
Gateways operate at this layer.
Protocols functioning at this layer TCP, UDP, IPSec, PPTP, RDP, L2TP
Network and transport layer protocol families
Reliability protocols. Provide method of ensuring reliable data transfer. Checksum value in header or trailer
Connection protocols. Establish and maintain s connection less or connection oriented server for the upper layers. In connection oriented the sending and receiving nodes maintain constant communication to mediate the transfer of data
In connection less the message is Packaged, delivered, and sent when communication exists between two nodes
Routing protocols. Ensures data transfer to the correct destination.
Explain checksum value
Lets the recover test the I integrity of received data. If corrupted the receiver fires back an error message to the sender to retransmit the data
Describe the session layer 5
Established connections between devices and applications, maintains the connection, and then Terminates or re establishes it when required.
Controls how, when, and for how long a device can transmit or receive data.
Sockets and session establishment in TCP function at this layer.
Describe the presentation layer 6
Responsible for encoding data into a standard network compatible format. Used to enable devices with different representation techniques to communicate with each other. Adds data compression and encryption.
Technologies and protocols operating at this layer are : MME, SSL, TLS, GIF, JPEG, TIFF
Technologies operating at the presentation layer 6
MME. Mesh Made Easy. Used for routing in wireless networks
GIF. Graphics Interchange Format. Graphic interchange format used on the Internet
JPEG. Joint photographic Experts Group. Graphical file format that reduced file size
TIFF. Tagged Image File Format. Digital format used to handle images used in publishing and photography
Protocols that function at the transport layer 4
TCP. Transmission Control Protocol UDP. User Datagram Protocol IPSec. Internet Protocol security PPTP. Point to Point Tunneling Protocol RDP. Remote Desktop Protocol L2TP Layer 2 Tunneling Protocol
Describe the application layer 7
Provides utilities and services that allow applications to access the network and it resources. Defines protocols for tasks, advertises itself to server resources available in each system for usage on the network. User directly interacts with this layer
Technologies, protocols and services that function at this layer: HHTP, DNS, FTP, Gopher, NFS, NTP, SNMP, SMTP, Telnet
Technologies, protocols, and services operating at the application layer 7
HTTP. hyper text transfer protocol DNS. Domain Name Service FTP. File Transfer Protocol NFS. Network File System NTP. Network Time Protocol SNMP. Simple Network Management Protocol SMTP. Simple Mail Transfer Protocol Telnet Gopher
Application, presentation, session layer protocol families
Terminal emulation protocols. Enable computers to act as standard terminals to access hosts
File access and file transfer protocols. Enables nodes to access files on the network
Email protocols. Email delivery and message handling
Remote action and multiple session protocols. Determines if processes performed remotely on s client node or directly by a server
Network management protocols. Provide tools for setting up and maintaining the network.
Task to task protocols. Enable software processes to communicate Over the network
Codeset and data structure protocols. Define the representation of data. Translate data for nodes using different coding schemes.
Describe the overall process of data transmission through the OSI model
During Data transmission data is added to the application layer 7. It is then forwarded to the lower layers until the physical layer 1 transfers the data to the network media.
During data reception, data is added to the physical layer 1. Then it is forwarded to the layers above it until it reaches the application layer 7. Each layer removes the information it needs before transmitting the remaining data to the next layer
Define the TCP/IP protocols
A network protocol suite that is routable and allows computers to communicate across all types of networks. Protocol of the Internet. Is non-proprietary.
