1.0 General Networking Flashcards
OSI Model
- The Application Layer
- The Presentation Layer
- The Session Layer
- The Transport Layer (Gateways)
- The Network Layer (Routers)
- The Data Link Layer (Switches, NIC)
- The Physical Layer (Cables, Wireless)
TCP/IP model
- Application
- Transport
- Network
- Data Link
- Physical Layers
Command Line Telnet / SSH
Putty
Telnet - Port 23
SSH - Port 22
can use the telnet <IP> command to telnet to other device</IP>
can use ssh -l <user> <IP> command to ssh</IP></user>
File transfer protocol (FTP)
Is a way to download, upload, and transfer files from one location to another on the Internet and between computer systems. FTP enables the transfer of files back and forth between computers or through the cloud. Users require an Internet connection in order to execute FTP transfers. FTP is built on a client-server model, using separate control and data connections between the client and the server. FTP works by opening two connections that link the computers trying to communicate with each other, over a TCP-based network, such as the Internet.
Trivial File Transfer Protocol (TFTP)
A simple protocol for exchanging files between two TCP/IP machines. TFTP is intended for applications that don’t need the sophisticated interactions that File Transfer Protocol (FTP) provides. TFTP is primarily used for transferring short configuration files to routers and other devices, typically over a short dedicated link or at least within a LAN environment.
Command Line FTP / TFTP
copy <protocol> <location> <IP></IP></location></protocol>
show inventory command
To display the product inventory listing of all Cisco products installed in the networking device, use the show inventory command in user EXEC or privileged EXEC mode.
1.1 Use the OSI and TCP/IP models and their associated protocols to explain how data flows in a network
** OSI Model Layers **
Application Layer (Layer 7)
At this layer, user applications interact with the network. Protocols such as HTTP (Hypertext Transfer Protocol), FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol), and SSH (Secure Shell) operate here.
Presentation Layer (Layer 6)
This layer is responsible for data translation, encryption, and compression. It ensures that data from the application layer is properly formatted for transmission over the network.
Session Layer (Layer 5)
The session layer establishes, maintains, and terminates communication sessions between applications. It manages dialogue control and synchronization between devices.
Transport Layer (Layer 4)
This layer provides end-to-end communication between hosts and ensures that data is reliably delivered. Protocols such as TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) operate at this layer.
Network Layer (Layer 3)
The network layer is responsible for routing packets across different networks. It uses logical addresses (such as IP addresses) to determine the best path for data transmission. Protocols like IP (Internet Protocol) and ICMP (Internet Control Message Protocol) operate here.
Data Link Layer (Layer 2)
This layer is responsible for the reliable transmission of data over a physical medium. It divides data into frames, adds addressing information, and detects and corrects errors. Protocols such as Ethernet, PPP (Point-to-Point Protocol), and MAC (Media Access Control) operate here.
Physical Layer (Layer 1)
- The physical layer deals with the physical transmission of data over the network medium. It defines the hardware specifications, such as cables, connectors, and signaling. Protocols such as Ethernet, Wi-Fi, and DSL (Digital Subscriber Line) operate here.
** TCP/IP Model Layers **
Application Layer
Similar to the OSI model’s application layer, this layer handles user applications and protocols such as HTTP, FTP, SMTP, and SSH.
Transport Layer
In the TCP/IP model, this layer combines the functions of the OSI model’s transport and session layers. It includes protocols such as TCP and UDP for end-to-end communication and error handling.
Internet Layer
Corresponding to the OSI model’s network layer, this layer handles routing and packet forwarding. The IP protocol is the primary protocol used here.
Link Layer (or Network Access Layer)
Combining the OSI model’s data link and physical layers, this layer deals with the physical transmission of data and the framing and addressing of packets. Protocols such as Ethernet, Wi-Fi, and PPP operate here.
Data Flow:
- When a user sends data from an application (e.g., a web browser) to a remote server (e.g., a web server), the data passes down the layers of the OSI or TCP/IP model.
- At each layer, the data is encapsulated with headers and possibly trailers, adding information necessary for that layer’s functionality.
- As the data moves through the layers, lower-level protocols handle tasks like addressing, error detection, and routing.
- Once the data reaches the physical layer, it is transmitted over the network medium (e.g., Ethernet cable, wireless signal).
- At the receiving end, the data is received, and the process is reversed: the data moves up the layers, with each layer stripping off its header or trailer until it reaches the application layer at the destination.
- Throughout this process, protocols at each layer ensure that the data is properly formatted, addressed, and transmitted, resulting in successful communication between the sender and receiver.
1.2 Describe the basic functionality and key differences of this hardware: LAN switch, router, and wireless access points
LAN Switch:
A LAN (Local Area Network) switch is a networking device that operates at the data link layer (Layer 2) or sometimes at the network layer (Layer 3) of the OSI model. Its primary function is to forward data packets within a local network, typically Ethernet-based. Switches use MAC addresses to forward packets between devices within the same network segment. They provide multiple ports to connect devices such as computers, printers, servers, and other network devices. Switches improve network performance by reducing collisions and enabling full-duplex communication between devices. They are used to create and manage local area networks, allowing devices within the same network segment to communicate efficiently. Switches do not perform routing functions or manage traffic between different networks.
Router:
Routers operate at Layer 3 of the OSI model, focusing on IP addresses for packet routing. Its primary function is to forward data packets between different networks or subnetworks. Routers use IP addresses to determine the best path for forwarding packets between networks. They provide connectivity between devices across different networks, such as connecting a local network to the internet or linking multiple branch offices in a wide area network (WAN). Routers often include features such as network address translation (NAT), firewall capabilities, and quality of service (QoS) settings. Routers handle tasks such as packet forwarding, routing table management, and network address translation (NAT) for internet connectivity.
Wireless Access Point (WAP):
Wireless access points operate at Layer 1 (physical layer) and Layer 2 (data link layer) of the OSI model. Their primary purpose is to provide wireless connectivity within a local area network (LAN). Its primary function is to provide wireless connectivity to devices such as laptops, smartphones, tablets, and IoT devices. WAPs transmit and receive wireless signals using Wi-Fi technology, allowing wireless devices to communicate with the network infrastructure. They typically connect to a wired network via an Ethernet cable and provide wireless coverage within a specific area or building. They are used to extend the reach of a wired network by providing wireless connectivity to devices. In larger wireless networks, multiple access points are often deployed to provide seamless coverage and support roaming for wireless devices.
1.3 Differentiate between these Layer 2 technologies: Ethernet, Fast Ethernet, Gigabit Ethernet, Serial, and Optical
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Ethernet:
Common Ethernet standards include 10BASE-T (10 Mbps over twisted pair copper cables), 100BASE-TX (100 Mbps over twisted pair cables), and 1000BASE-T (1 Gbps over twisted pair cables). -
Fast Ethernet:
- It operates at 100 Mbps, ten times faster than traditional Ethernet.
- Fast Ethernet maintains backward compatibility with Ethernet, meaning it can interoperate with Ethernet devices.
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Gigabit Ethernet:
- It operates at 1000 Mbps (1 Gbps), ten times faster than Fast Ethernet and a hundred times faster than traditional Ethernet.
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Serial:
- Serial refers to a communication interface that transmits data serially, one bit at a time, over a single channel.
- Serial interfaces are commonly used in networking for connecting devices over long distances using serial communication protocols such as RS-232, RS-422, or RS-485.
- Serial connections are often used in point-to-point communication between networking devices like routers, switches, and serial consoles.
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Optical:
- Optical networking technologies use light signals to transmit data over fiber optic cables.
- Optical networks offer high bandwidth, low latency, and immunity to electromagnetic interference.
- Common optical networking standards include SONET/SDH (Synchronous Optical Networking/Synchronous Digital Hierarchy) and Ethernet over Fiber (such as 1000BASE-SX, 1000BASE-LX, and 10GBASE-SR).
1.4 Describe LAN cabling
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Twisted Pair Cable:
- Twisted pair cable is the most common type of LAN cabling and is widely used for Ethernet networks.
- It consists of pairs of insulated copper wires twisted together to reduce electromagnetic interference (EMI) and crosstalk.
- Common categories include Cat 5e, Cat 6, Cat 6a, and Cat 7.
- Cat 5e (Category 5e) is suitable for most Ethernet networks and supports data rates up to 1 Gbps (Gigabit Ethernet).
- Cat 6 (Category 6) and higher grades offer higher performance and support higher data rates, making them suitable for applications requiring faster network speeds or longer cable runs.
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Coaxial Cable:
- Coaxial cable consists of a single inner conductor surrounded by a layer of insulation, a conductive shield, and an outer insulating layer.
- Coaxial cable was commonly used in older Ethernet networks, particularly for cable television (CATV) and broadband internet connections.
- Although less common in modern LAN installations, coaxial cable is still used in certain specialized applications, such as in cable television networks and CCTV systems.
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Fiber Optic Cable:
- Fiber optic cable uses glass or plastic fibers to transmit data using light signals. They offers high bandwidth, low latency, and immunity to electromagnetic interference (EMI).
- They are available in different types, including single-mode fiber (SMF) and multi-mode fiber (MMF).
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Power over Ethernet (PoE) Cabling:
- Power over Ethernet (PoE) cabling combines power and data transmission over a single Ethernet cable which allows network devices such as IP phones, wireless access points, and security cameras to receive power from the Ethernet cable.
1.5 Describe the function of CSU/DSU
A CSU/DSU (Channel Service Unit/Data Service Unit) is a networking device used to connect a data terminal equipment (DTE) device, such as a router or switch, to a digital circuit, typically a T1 or T3 line. They perform several critical functions in the transmission of data over digital telecommunications lines:
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Channel Service Unit (CSU):
- The CSU is responsible for interfacing with the telecommunications network provider’s equipment. It ensures that the data being transmitted conforms to the standards and specifications required by the telecommunications network.
- CSUs handle tasks such as line conditioning, which includes amplifying and equalizing the signal to ensure reliable transmission over long distances.
- They also monitor the integrity of the connection and can provide diagnostics and status information about the line quality.
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Data Service Unit (DSU):
- The DSU is responsible for managing the data interface between the customer’s equipment (DTE) and the digital circuit provided by the CSU.
- DSUs perform functions such as converting the data format between the serial interface of the DTE device and the digital format used on the telecommunications line.
- They manage the timing and synchronization of data transmission to ensure that data is sent and received at the correct rate and in the proper sequence.
- DSUs may also provide error detection and correction mechanisms to ensure the integrity of the transmitted data.
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Integration:
- Together, the CSU and DSU provide a complete interface between the customer’s equipment and the telecommunications network. They bridge the gap between the digital circuit provided by the carrier and the data communications equipment used by the customer.
- CSU/DSU devices are typically used in scenarios where high-speed digital circuits, such as T1 or T3 lines, are used to connect remote sites, branch offices, or data centers to a wide area network (WAN) or the internet.
1.6 Describe Telco termination point
A Telco termination point, short for telecommunications termination point, refers to the physical endpoint or interface where a telecommunications service provided by a telecommunication company (telco) terminates or connects to a customer’s premises or network infrastructure. The termination point marks the boundary between the telco’s network and the customer’s network, serving as the demarcation point for responsibility and ownership of the telecommunications service.
Key aspects of Telco termination points include:
- Location: Telco termination points are typically located at the customer’s premises, often near the entry point where the telco’s network connects to the customer’s building or property. They are commonly found on exterior walls or in utility rooms where telecommunications equipment is installed.
- Physical Infrastructure: The termination point may include physical components such as junction boxes, network interface devices (NIDs), distribution panels, or termination blocks. These components provide the necessary interface for connecting telecommunications cables from the telco’s network to the customer’s internal wiring or equipment.
- Responsibility: The telco termination point serves as the demarcation point between the telco’s responsibility for providing and maintaining the telecommunications service up to that point and the customer’s responsibility for maintaining the service beyond that point. Any issues or faults occurring before the termination point are typically the telco’s responsibility to resolve, while issues occurring after the termination point are the customer’s responsibility.
- Connection Interface: Telco termination points provide standardized interfaces for connecting telecommunications cables, allowing for easy connection and disconnection of services. These interfaces may include RJ-11 or RJ-45 jacks, coaxial cable connectors, or fiber optic connectors, depending on the type of service being provided (e.g., telephone, internet, TV).
- Testing and Diagnosis: Telco termination points often include provisions for testing and diagnosing telecommunications services. This may involve test jacks or test points that allow technicians to measure signal strength, perform line tests, or troubleshoot connectivity issues.
1.7 Describe an IPv4 and IPv6 address and subnet
IPv4 Address:
An IPv4 (Internet Protocol version 4) address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. IPv4 addresses are 32 bits in length and are typically expressed in dotted-decimal notation, where each 8-bit segment is represented as a decimal number separated by periods. For example, an IPv4 address might look like this: 192.168.1.1.
IPv4 addresses are divided into two main parts: the network portion and the host portion. The network portion identifies the network to which the device is connected, while the host portion identifies the specific device within that network. IPv4 addresses are further divided into classes (A, B, C, D, and E) based on their leading bits and address ranges.
IPv6 Address:
An IPv6 (Internet Protocol version 6) address is a numerical label assigned to each device connected to a computer network that uses IPv6 for communication. IPv6 addresses are 128 bits in length, providing a significantly larger address space compared to IPv4. IPv6 addresses are typically expressed as eight groups of four hexadecimal digits separated by colons. For example, an IPv6 address might look like this: 2001:0db8:85a3:0000:0000:8a2e:0370:7334.
IPv6 addresses also have a network portion and a host portion, similar to IPv4 addresses. However, IPv6 does not use traditional subnet masks like IPv4. Instead, IPv6 networks are typically assigned a prefix length, represented as a slash followed by a number indicating the number of bits in the network portion. For example, a prefix length of /64 indicates that the first 64 bits of the IPv6 address represent the network, while the remaining bits represent the host.
Subnet:
A subnet, short for subnetwork, is a logical subdivision of an IP network. Subnetting allows a larger network to be divided into smaller, more manageable segments for organizational, security, or performance reasons. Each subnet has its own unique range of IP addresses, which are used to identify devices within that subnet.
Subnetting involves borrowing bits from the host portion of an IP address to create a subnet mask, which defines the boundary between the network portion and the host portion. The subnet mask determines how many bits are reserved for the network portion and how many are reserved for the host portion within each subnet.
For example, a subnet mask of 255.255.255.0 in IPv4 (or /24 in CIDR notation) indicates that the first 24 bits of the IP address represent the network portion, while the remaining 8 bits represent the host portion. This allows for up to 254 hosts within each subnet.
Similarly, in IPv6, a prefix length of /64 indicates that the first 64 bits of the IPv6 address represent the network portion, while the remaining 64 bits represent the host portion. This is a common prefix length used in IPv6 subnetting, allowing for a large number of subnets with a large number of hosts each.
1.8a Describe the function of FTP
FTP (File Transfer Protocol):
FTP is a standard network protocol used for transferring files between a client and a server on a computer network. It enables users to upload files from their local system to a remote server or download files from a remote server to their local system. FTP operates on a client-server model, where the client initiates a connection to the server using the FTP protocol. It supports various operations such as file listing, file upload, file download, file deletion, directory creation, and directory navigation.
FTP operates over TCP/IP and typically uses ports 20 and 21 for data transfer and control, respectively. It supports both anonymous and authenticated access, allowing users to connect to FTP servers with or without providing login credentials. FTP sessions can be secured using protocols like FTPS (FTP Secure) or SFTP (SSH File Transfer Protocol) to encrypt the data transmitted over the network.
