NWIT 275 - Week 1: Layered Networking Models (OSI and IP Models)

Flashcards covering key vocabulary and concepts from the NWIT 275 Week 1 lecture on Layered Networking Models, including the OSI and TCP/IP models and their respective layers.

Layered Networking Models

Schematic frameworks that describe all the functions devices must implement for meaningful communication to occur by breaking networking tasks into layers responsible for specific functionalities.

OSI Model

The Open Systems Interconnection Reference Model is a generic, ideal network model that describes how a network would behave and function, covering all tasks for end-to-end communications.

TCP/IP Model

A less formal, public networking model based on the TCP/IP protocol suite, outlining the interconnection between network devices on the Internet; considered an implementation of OSI for the internet.

Benefits of Layering

Isolates specific functions into modular components, reduces complexity, makes changes transparent to other layers, helps standardize interfaces, facilitates modular engineering, accelerates technical evolution, aids troubleshooting, and simplifies teaching/learning network communications.

Physical Layer (OSI Layer 1)

Responsible for transmitting bits (1s and 0s) over the communication medium (wired or wireless), specifying electrical, mechanical, procedural, and functional means for activating/maintaining physical links (e.g., connectors, voltages, encoding, fiber optics, hubs).

Data Link Layer (OSI Layer 2)

Defines specifications for delivering data across one physical link, handles error notification, network topology, and flow control. Uses MAC addresses for machine identification and is divided into LLC and MAC sub-layers (e.g., Ethernet, switches, NICs).

Logical Link Control (LLC) Sublayer

A sub-layer of the Data Link Layer (OSI Layer 2) that creates and manages the link, deals with transmission errors (detection, correction, retransmission), and identifies the upper layer protocol being carried in the packet.

Medium Access Control (MAC) Sublayer

A sub-layer of the Data Link Layer (OSI Layer 2) that determines how computers share a common channel (access the network), moves data on/off cabling in proper 'frame' format, and adds unique MAC addresses.

Network Layer (OSI Layer 3)

Defines end-to-end delivery of independently addressed data units (datagrams), defines logical addressing (e.g., IP addresses), and determines the best way to move data between networks (routing) (e.g., IP, ICMP, routers, Layer 3 switches).

Transport Layer (OSI Layer 4)

Focuses on the quality of data delivery (efficient, reliable, cost-effective), including error recovery, segmentation, reassembly, establishment of logical connections, and flow control (e.g., TCP, UDP, Layer 4-7 switches).

Session Layer (OSI Layer 5)

Defines how to establish, maintain, and manage conversations (sessions) between applications, including control and management of multiple bidirectional messages (e.g., NetBIOS, SSL, NFS, RPC).

Presentation Layer (OSI Layer 6)

Defines the formatting of data to ensure it can be understood by the destination application, provides coding and conversion functions, and handles encryption and compression (e.g., ASCII, JPEG, MPEG).

Application Layer (OSI Layer 7)

Defines the interface between communications software and applications needing to communicate outside the device, providing network services to user applications (e.g., HTTP, SMTP, DNS, DHCP, proxy servers). End-user applications themselves are not part of this layer.

Network Interface Layer (TCP/IP Model)

Defines the protocols and hardware needed to deliver data across a 'physical' network, handling communication from a host to the physical medium it resides on. Also known as the Link Layer (e.g., Ethernet, ARP, NICs, Layer 2 switches).

Internetwork Layer (TCP/IP Model)

Handles the movement of packets around the network (routing), getting data closer to its destination one 'hop' at a time. Also known as the Network Layer (e.g., IP, routers, Layer 3 switches).

Transport Layer (TCP/IP Model)

Responsible for the flow of data between two hosts, including error detection and ensuring reliable or unreliable delivery (e.g., TCP for reliable, UDP for unreliable).

Application Layer (TCP/IP Model)

Provides services that applications need, such as file transfer, and acts as an interface between software running on the device and the network itself. Defines services, not the applications themselves (e.g., TFTP, HTTP, SMTP, DNS).