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Which type of network typically connects computing devices over a small geographic area such as a building or a department?
In network architecture, which setup allows each node to act as both a client and a server?
Which of the following devices would NOT typically be considered a processing device in a computer network?
What characteristic best differentiates a Local Area Network (LAN) from a Wide Area Network (WAN)?
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Which term best describes a device that requests access to resources on a network?
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Which of the following accurately defines a Wide Area Network (WAN)?
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What is a primary characteristic of a Personal Area Network (PAN)?
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In a Home Area Network (HAN), what is typically used for connecting devices?
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Which statement is true regarding Peer-to-Peer (P2P) network architecture?
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What distinguishes Client/Server network architecture from Peer-to-Peer?
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Which of the following is NOT a characteristic of a Wide Area Network?
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Which example best represents a Personal Area Network (PAN)?
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Which description is accurate for the connection types found in a WAN?
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What type of devices are commonly connected in a Home Area Network (HAN)?
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Which statement best describes a possible limitation of a Peer-to-Peer (P2P) network?
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What transfer method is used in the Transport Layer to ensure that data segments are sequenced in order?
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Which function is primarily associated with the Data Link Layer?
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What is the primary protocol data unit (PDU) of the Network Layer?
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What type of delivery does the Transport Layer provide that involves maintaining a virtual circuit?
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In which layer is data compressed, encrypted, or encoded before being passed to the next layer?
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What does the physical topology in the Physical Layer relate to?
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What method is typically used by routers to determine the best path for forwarding data packets?
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What is the primary purpose of the OSI model's layered architecture?
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Which layers of the OSI model are responsible for communication between host applications?
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What is the correct term for the data units created by the OSI model's layers during data transmission?
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Which statement accurately describes the encapsulation process in the OSI model?
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How do peer layers in the OSI model communicate?
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What role does the Application Layer (Layer 7) serve in the OSI model?
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What is the main distinction between upper layers and lower layers in the OSI model?
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What does the OSI model enable through industry standardization?
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Which category of twisted pair cables is capable of transmitting data at a rate of 10,000 Mbps?
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What is the function of the jam signal in the CSMA/CD protocol?
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Which type of cable is characterized by individually insulated copper wires twisted in pairs?
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Which type of fibre-optic cable is designed for longer distances and less signal loss?
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What is a key advantage of fibre-optic cables over copper cables?
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What distinguishes broadband from baseband in data transmission?
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What distinguishes a broadcast domain from a collision domain in networking?
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Which type of interference is primarily caused by radio signals?
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Which coaxial cable variant is characterized by a maximum segment length of 200 m and supports up to 30 nodes?
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Which twisted pair category provides a maximum transmission frequency of 100 MHz?
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What is the primary material in coaxial cables that enhances their capability to reduce EMI and RFI?
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Which type of connector is characterized by a mechanical transfer registered jack?
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What factors primarily determine throughput in data transmission?
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What is the maximum distance limit for Twisted Pair cables in standard applications?
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Which type of connector is specifically associated with coaxial cables?
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What is the primary function of the Application Layer in the TCP/IP model?
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Which of the following accurately describes a function of the Internet Layer?
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What type of Protocol Data Unit (PDU) is used by the Transport Layer?
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In the context of the TCP/IP model, which statement correctly describes TCP?
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Which aspect differentiates TCP from UDP in terms of communication?
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Which layer in the TCP/IP model is responsible for adding headers and trailers for transmission?
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What is the primary purpose of the encapsulation process in the TCP/IP model?
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Which of the following transport protocols is acknowledged for connection-oriented communication?
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Which protocol is responsible for resolving the MAC address from a known IP address?
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What unit of information is handled by the Data Link Layer during encapsulation?
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Which network access layer protocol is specifically used for wired connections?
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In the decapsulation process, what is the immediate action taken by the Internet layer?
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Which of the following best describes the function of Traceroute?
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What is the purpose of the frame header added during the encapsulation process?
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Which encapsulation unit does the physical layer handle in the OSI model?
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Study Notes
Basic Definitions
- A computer network is two or more computing devices that are connected to communicate or share resources, such as data, software applications, or hardware devices.
- A node is a computing device on a computer network. Some examples are processing devices such as phones, tablets, laptops, desktops, and servers; input devices such as scanners and cameras; output devices such as printers and displays; storage devices such as network attached storage (NAS); and navigation devices such as switches, access points, routers, and firewalls.
- A client requests access to a resource.
- A server provides access to a resource. Some examples are file servers, print servers, mail servers, web servers, database servers, and application servers.
Types of Networks (Distance)
- A Local Area Network (LAN) connects two or more nodes and covers a small geographic area, like a room, floor, building, compound, department, or branch. It has a constant, private, and fast connection (100 Mbps or more).
- A Metropolitan Area Network (MAN) covers a moderate geographic area, such as a city.
- A Wide Area Network (WAN) connects two or more networks and covers a large geographic area, such as cities across a country, countries across the world, or the internet. It has an occasional, public, and slow connection (100 Mbps or less).
- A Personal Area Network (PAN) connects devices via Bluetooth, such as phones, tablets, laptops, desktops, speakers, keyboards, mice, and smart devices like fitness trackers, scales, blood pressure and blood glucose machines.
- A Home Area Network (HAN) connects devices within a home, typically via Wi-Fi using a wireless router.
Types of Networks (Architecture)
- Peer-to-peer (P2P) networks have computers with mixed roles of client and server with no central authority for access and resources. This is a basic operating system feature that is offered by Windows 10, 8.x, 7, and XP, macOS, and Linux.
- Client/Server networks have computers with dedicated roles of either client or server and have a central authority for access and resources. It is an advanced operating system feature and is offered by Windows Server 2019, 2016, 2012, 2003, macOS Server, Linux, and UNIX.
Types of Networks (Topology)
- Physical topology refers to how devices are physically connected.
- Logical topology refers to how data flows.
Bus Topology
- This topology uses a single cable (called a backbone) between two terminators with nodes connected to the backbone.
- It is hardly used today.
- Advantages: Inexpensive and easy to implement.
- Disadvantages: Difficult to add, move, or change devices, difficult to troubleshoot, all components are a single point of failure, prone to congestion due to broadcasts, and all data is seen by all nodes.
Ring Topology
- This topology has nodes connected in sequence, with each node connected to the previous and next node. The last node is then connected to the first node.
- This topology is used for WANs.
- Advantages: Inexpensive and easy to implement, easy to add, move, or change devices, and easy to troubleshoot.
- Disadvantages: All components are a single point of failure and all data is seen by all nodes.
Star Topology
- This topology has a central device with individual cables connecting each node.
- This topology is used for LAN "edges", meaning client computers.
- Advantages: Easy to implement, easy to add, move, or change devices, easy to troubleshoot, no single point of failure for cables or nodes, less congestion due to fewer broadcasts, and data is seen by the target node.
- Disadvantages: Expensive to implement and the central device is a single point of failure.
Mesh Topology
- This topology has each node connected to each other node. The number of connections is calculated using the formula N(N-1)/2.
- This topology is used for LAN “core”, meaning server computers.
Hybrid Topology
- This topology is a mix of two or more topologies.
Basic Definitions
- A protocol is a set of rules that enable communication between two or more network nodes by transmitting and receiving data.
Background
- Early computer networks were "closed" systems, meaning they were tied to specific vendor technologies, like IBM's SNA or DEC's DECNet.
- The International Organization for Standards (ISO) developed the OSI Model, an architectural blueprint for "open" communication, promoting compatibility between applications, protocols, services, and devices.
- The OSI Model allows for interoperability through industry standardization and multi-vendor development.
Layered Architectures
- The OSI Model is a layered architecture that simplifies the development, design, implementation, and support of network components.
- It defines who does what, when, and how during network communication.
- It's important to understand that it's a reference model, not an implementation model.
The 7 Layers
- The OSI model has seven layers, often remembered by the acronym "All People Seem To Need Data Processing":
- Application Layer (Layer 7)
- Presentation Layer (Layer 6)
- Session Layer (Layer 5)
- Transport Layer (Layer 4)
- Network Layer (Layer 3)
- Data Link Layer (Layer 2)
- Physical Layer (Layer 1)
Upper vs Lower Layers
- The upper layers (5-7) are responsible for communication between host applications.
- The lower layers (1-4) are responsible for the actual data transmission between hosts.
Peer Layers
- Layers communicate logically with their corresponding layers in other devices.
Service Layers
- Layers communicate physically with their lower layers.
Encapsulation
- As data travels down the layers, each lower layer adds its own protocol data unit (PDU) with a header and sometimes a trailer.
- This process is called encapsulation.
- Each sender layer communicates with the corresponding receiver layer.
Decapsulation
- As data travels up the layers, each higher layer removes the PDU of the lower layer.
- This process is called decapsulation.
Layer 7: Application Layer
- This layer provides a user interface for applications and handles communication protocols for applications.
- Examples of application protocols include:
- HTTP for web browsers
- SMTP/IMAP/POP for email clients
- FTP for file transfer applications
- The application layer encapsulates data to be sent to the Presentation Layer.
Layer 6: Presentation Layer
- This layer is responsible for translating and formatting data, ensuring consistent presentation across different systems.
- Processes include:
- Encoding/Decoding
- Encrypting/Decrypting
- Compressing/Decompressing
- The Presentation layer encapsulates data to be sent to the Session Layer.
Layer 5: Session Layer
- This layer manages the communication session between applications, controlling dialog flow and data separation between different applications.
- Session types include:
- Simplex (unidirectional)
- Half duplex (bidirectional asynchronous)
- Full duplex (bidirectional synchronous)
- The Session layer encapsulates data to be sent to the Transport Layer.
Layer 4: Transport Layer
- This layer provides end-to-end connection between hosts, establishing a logical connection (virtual circuit).
- It segments data into data streams and ensures reliable or unreliable delivery.
- Delivery types include:
- Reliable (connection-oriented)
- Unreliable (connection-less)
- The Transport layer encapsulates data to be sent to the Network Layer.
Connection-Oriented Transport
- Uses a three-way handshake (SYN, SYN/ACK, ACK) to establish a virtual circuit between the sender and receiver.
- Maintains flow control using acknowledgments, retransmissions, and segment sequencing.
- Windowing is used to specify the number of segments acknowledged at a time.
Layer 3: Network Layer
- This layer provides logical addressing of hosts, identifying and locating them on a network.
- Encapsulates data into a packet.
- It is responsible for routing data between networks using routing tables.
- Routers use routing tables to:
- Accept data destined for their network.
- Forward data destined for known networks.
- Drop data destined for unknown networks.
- The Network layer encapsulates data to be sent to the Data Link Layer.
Layer 2: Data Link Layer
- This layer provides hardware addressing of devices, identifying and locating nodes on the network.
- Encapsulates data into a frame.
- It's responsible for:
- Framing
- Error detection (not correction)
- Defining the logical topology.
- The Data Link layer encapsulates data to be sent to the Physical Layer.
Layer 1: Physical Layer
- Deals with the physical transmission of data, converting data into electrical, light, or audio signals for transmission.
- Encapsulates data into a bit.
- Provides the physical topology for data transmission.
- The Physical layer transmits bits to the transmission media.
Transmission Media
- Actual physical carriers for data transmission, including copper cable, fiber optic cable, and wireless media.
Transmission Media
- Wired and wireless transmission media are two main categories.
- Wired media include copper, fiber, and various types of cables.
- Wireless media include Bluetooth, Wi-Fi, and microwaves.
Basic Definitions
- Digital data is discrete states, while analog data is continuous states.
- Data transfer rates are measured in bits per second (bps).
- Bandwidth is the maximum data transfer rate possible.
- Throughput is the actual data transfer rate, which is less than or equal to bandwidth.
- Broadband allows multiple data streams, while baseband uses a single data stream.
- Electromagnetic Interference (EMI) is caused by electrical and/or magnetic signals.
- Radio Frequency Interference (RFI) is caused by the presence of radio signals.
- Attenuation is the signal loss caused by degradation over distance.
Copper
- Copper is a soft, malleable, and ductile metal.
- It is a good conductor of heat and electricity.
- Data is transmitted as analog signals.
Coaxial Cable
- Coaxial cable consists of a thick copper wire surrounded by three layers: plastic jacket, braided shield, and plastic insulation (PVC or Teflon).
- These layers reduce EMI and RFI.
- Thin Ethernet (Thinnet) and Thick Ethernet (Thicknet) are two common coaxial cable types.
- Thinnet (10 Base 2) supports 10 Mbps, baseband, up to 200 meters, and uses RG-58 cable.
- Thicknet (10 Base 5) supports 10 Mbps, baseband, up to 500 meters, and uses RG-8 cable.
Coaxial Connectors
- Two common coaxial connectors are the F-type connector (75 ohm) and the BNC connector (50 ohm).
Twisted Pair
- Twisted pair consists of individually insulated copper wires twisted in pairs.
- The twists reduce crosstalk and EMI/RFI.
- Twisted pairs are limited to 100 meters.
Twisted Pair Cables
- There are two types of twisted pair cables: Shielded (STP) and Unshielded (UTP).
Twisted Pair Connectors
- Common twisted pair connectors include the RJ-11 (telephone jack) and the RJ-45.
Previous Twisted Pair Categories
- Cat 1: Voice grade (POTS) with 2 pairs (4 wires).
- Cat 2: 4 Mbps (Early Token Ring) with 4 pairs (8 wires).
- Cat 3: 10 Mbps (10 Base T) with 4 pairs (8 wires).
- Cat 4: 16 Mbps (Newer Token Ring) with 4 pairs (8 wires).
Current Twisted Pair Categories
- Cat 5: 100 MHz / 2 pairs; 100 Mbps (100 Base TX).
- Cat 5e: 100 MHz / 4 pairs; 1,000 Mbps (1000 Base T).
- Cat 6: 250 MHz / 2 pairs; 1,000 Mbps (1000 Base TX).
- Cat 6a: 500 MHz / 4 pairs; 10,000 Mbps (10G Base T).
Collision Domains
- A collision domain is a physical segment where all nodes hear all communication.
- Hubs create a single collision domain.
Broadcast Domains
- A broadcast domain is a physical segment where all nodes hear all broadcasts.
- Switches create a single broadcast domain.
Carrier Sense Multiple Access with Collision Detect (CSMA/CD)
- Nodes listen to the wire (carrier sense) before transmitting.
- If multiple nodes transmit at the same time, a collision occurs.
- Nodes send a jam signal and use the back-off algorithm to wait and resend.
Fiber Optic
- Fiber optic cable consists of a flexible, transparent strand of glass or plastic (thinner than a human hair) that transmits light between its ends.
- It allows longer distances and higher bandwidths compared to copper cables.
- Data is transmitted digitally.
Fiber-Optic
- The core is made of glass or plastic and surrounded by cladding, plastic, armor coating, (usually Kevlar) and PVC or Teflon.
- Fiber optic is immune to EMI and RFI.
- It is expensive to implement and support.
Fiber-Optic Cables
- Two types of fiber optic cables are multimode fiber (MMF) and single-mode fiber (SMF).
Fiber-Optic Connectors
- Fiber optic connectors come in various types:
- Angled Physical Contact (APC) vs Ultra Physical Contact (UPC)
- Straight Tip (ST) vs Subscriber or Square Connector (SC)
- Small Form Factor Connectors: Mechanical Transfer Registered Jack (MTRJ) vs Local Connector (LC)
Media Converters
- Media converters are used to connect different types of media within a network.
TCP/IP Model
- This will be covered in the next lecture.
TCP/IP Model Overview
- TCP/IP model originated in the DoD ARPANet
- TCP/IP model popularized through Unix BSD “shareware” and “open source"
- TCP/IP replaced other implementation models including Novell IPX/SPX, Apple AppleTalk, and IBM/Microsoft NetBEUI
- TCP/IP model is based on four layers: Application, Transport, Internet, and Network Access
- Application, Transport, Internet, and Network Access layers correspond to layers 7-5, 4, 3, and 2-1 respectively, from the OSI model.
- The Application Layer handles communication between host applications
- The Transport, Internet, and Network Access layers are responsible for data transmission between hosts
- Peer layers logically communicate with their corresponding layers across different hosts
- Service layers communicate physically with their lower layers on the same host
- Encapsulation occurs when the sender's data is wrapped in Protocol Data Units (PDUs) by each lower layer, adding header and sometimes trailer.
- Layers on the sender communicate with corresponding layers on the receiver
Application Layer
- The Application Layer uses data as the protocol data unit.
- The Appplication Layer performs encoding, encryption, and data compression.
- The Application Layer passes data to Transport Layer.
- Examples of Application protocols include web services, mail services, file services, print services, remote access services, and miscellaneous services.
Application Layer Protocols
-
Web services:
- Hypertext Transfer Protocol (HTTP)
- Hypertext Transfer Protocol Secure (HTTPS)
-
Mail Services:
- Simple Mail Transfer Protocol (SMTP)
- Post Office Protocol (POP)
- Internet Message Access Protocol (IMAP)
-
File Services:
- File Transfer Protocol (FTP)
- File Transfer Protocol Secure (FTPS)
- SSH FTP (SFTP)
- Trivial File Transfer Protocol (TFTP)
- Server Message Block (SMB)
-
Print Services:
- Server Message Block (SMB)
-
Remote Access Services:
- Telnet
- Secure Shell (SSH)
- Remote Desktop Protocol (RDP)
-
Miscellaneous Services:
- Dynamic Host Configuration Protocol (DHCP)
- Domain Name Service (DNS)
- Network Time Protocol (NTP)
- Simple Network Management Protocol (SNMP)
Transport Layer
- The Transport Layer uses segments as the protocol data unit.
- The Transport Layer performs sequencing and data integrity checks
- The Transport Layer uses port numbers for simultaneous conversations between hosts
- Target Ports: well-known port numbers below 1023
- Source Ports: dynamically assigned port numbers above 1024
- The Transport Layer adds a Segment Header and passes segments to the Internet Layer.
- Examples of Transport protocols include: TCP and UDP.
Transport Layer Protocols
-
TCP:
- Connection-oriented
- Reliable
- Segments data, numbers segments and awaits acknowledgment for the segments
- Full Duplex
-
UDP:
- Connectionless
- Unreliable
- Segments data without numbering and acknowledgment
- Simplex
Internet Layer
- The Internet Layer uses packets as the protocol data unit
- The Internet Layer is responsible for logical addressing using IP addresses
- The Internet Layer determines the best path to route packets across the network
- The Internet Layer adds a Packet Header and passes packets to the Network Access Layer.
- Examples of Internet layer protocols include: IP, ICMP, ARP.
Internet Layer Protocols
-
IP (Internet Protocol)
- The IP protocol looks at each packet’s destination address and uses a routing table to determine where to send the packet (network) and how (the best path).
-
ICMP (Internet Control Message Protocol)
- ICMP provides hosts with information about network problems, e.g., destination unreachable or buffer full.
-
ARP (Address Resolution Protocol)
- ARP finds a physical hardware (MAC) address from a known logical software (IP) address
- Ping: uses echo request and reply messages to check the physical & logical connectivity of hosts
- Traceroute: uses Time-to-Live (TTL) timeouts to discover the path packets travel
Network Access Layer
- The Network Access Layer uses frames and bits as the protocol data unit.
- The Network Access Layer is responsible for hardware addressing using MAC addresses, topology, and physical transmission.
- The Network Access Layer adds a frame header and trailer and passes bits to the Transmission Media.
- Examples of Network Access Layer Protocols include: 802.3, 802.4, 802.5, and 802.11.
Network Access Layer Protocols
-
Wired:
- 802.3: Ethernet (CSMA/CD)
- 802.4: Token Passing Bus
- 802.5: Token Passing Ring
-
Wireless:
- 802.11: Wi-Fi (CSMA/CA)
- 802.15: Wireless PAN
Decapsulation
- The Transport Layer passes data to the Application Layer
- The Internet Layer passes segments to the Transport Layer
- The Network Access Layer passes packets to the Internet Layer
- The Transmission Media passes bits to the Network Access Layer
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Description
This quiz covers fundamental definitions related to computer networks, including network nodes, clients, and servers. You will also learn about different types of networks, specifically Local Area Networks (LAN). Test your understanding of these key concepts in networking.
