Network Models, Protocols, and Router OS Access Methods

Flashcards reviewing the OSI model layers, TCP/IP model layers, network protocols, mapping between OSI and TCP/IP, and functional examples.

What is the OSI Model and when was it created?

The OSI (Open Systems Interconnection) Model is a conceptual framework created by the International Organization for Standardization (ISO) in 1984 that standardizes how network protocols and devices communicate by dividing functions into seven distinct layers.

How does data travel through the OSI Model layers during transmission?

Data travels down through the layers on the sending device (from Layer 7 to Layer 1) and back up through the layers on the receiving device (from Layer 1 to Layer 7).

What is the purpose of OSI Layer 7 (Application Layer) and what are some examples of its protocols?

Layer 7 provides network services directly to users and software applications. Examples of protocols include HTTP, HTTPS, FTP, SMTP, and DNS.

What are the main functions of OSI Layer 6 (Presentation Layer)?

Translation, Encryption, Decryption, Compression, and Decompression.

How does encryption function within network data protection as depicted in the Presentation Layer framework?

Encryption transforms plain data into a secure, unreadable format to keep it safe during transmission.

What are the four main functions of OSI Layer 5 (Session Layer)?

Session Establishment, Session Management, Synchronization (adding checkpoints so communication can resume if interrupted), and Session Termination.

What are the main functions performed by OSI Layer 4 (Transport Layer)?

Segmentation, Reassembly, Reliable Delivery, Flow Control, Error Recovery, and Port Addressing.

How does the Transport Layer (Layer 4) process data as it moves down to the Network Layer?

The Transport Layer breaks large data received from the Session Layer into smaller segments before passing them to the Network Layer.

What is the primary responsibility of OSI Layer 3 (Network Layer)?

Logical addressing and routing, which determines the best path for data to travel from the source device to the destination device across networks.

How does data packet routing function across routers at the Network Layer as shown in this network diagram?

Computer A (192.168.1.1) sends a data packet addressed to IP 192.168.1.2 through Router 1, which routes it to Router 3, and then delivers it to Computer B.

What are the main functions of OSI Layer 2 (Data Link Layer)?

Framing, Physical Addressing (using MAC addresses), Error Detection, Media Access Control, and Flow Control for node-to-node communication on the local network.

How is an Ethernet Frame used by a network switch at the Data Link Layer in this example?

An Ethernet Frame with Source MAC AAA and Destination MAC BBB is transmitted through port 1 of the switch to reach Computer B (MAC: BBB) on port 2.

What mechanisms does the Data Link Layer use to detect errors in transmitted frames?

Frame Check Sequence (FCS) or CRC (Cyclic Redundancy Check).

What are the main functions of OSI Layer 1 (Physical Layer)?

Bit Transmission (raw 0s and 1s), Physical Connection (cables, connectors, ports, wireless), Signal Encoding, Data Rate definition, and Physical Topology description.

What does TCP/IP stand for and how does it compare to the OSI Model?

TCP/IP stands for Transmission Control Protocol / Internet Protocol. It is the practical 4-layer protocol suite used in real-world networking, whereas OSI is a theoretical 7-layer reference framework.

Which protocols are categorized under each of the 4 layers of the TCP/IP Model?

Application: HTTPS, TLS, DNS; Transport: TCP, UDP; Internet: IPv4, IPv6; Network: Ethernet, Wireless LAN.

How do the 7 layers of the OSI Model map to the 4 layers of the TCP/IP Model?

OSI Application, Presentation, and Session map to TCP/IP Application; OSI Transport maps to Transport; OSI Network maps to Internet; OSI Data Link and Physical map to Network Access (or Network Interface/Hardware).

What key characteristics contrast the OSI Model with the TCP/IP Model?

OSI has 7 layers, is a conceptual reference framework, and is an ISO standard; TCP/IP has 4 layers, is a practical real-world internet model, and is an Internet standard.