Network Equipments Lecture 3 PDF

Network Hardware Lecture Outline  Classification of network equipment  Communication modes  Terminologies  Collision domain OSI Model Relationship between model layers Transfer of information between two stations Relationship Between models and protocols Network Hardwar...

Network Hardware Lecture Outline  Classification of network equipment  Communication modes  Terminologies  Collision domain OSI Model Relationship between model layers Transfer of information between two stations Relationship Between models and protocols Network Hardware Switch Patch cord Hub Modem Network adapter Bridge Access point Router twisted pair Repeater Optical fiber Firewall Splitter IDS/IPS Patch panel Network Equipment Classification (1/3) By power consumption :  Active  Passive By the presence of control (programming):  controlled (programmable)  unmanageable Network Equipment Classification (2/3) By OSI model layers on which the equipment works: Firewall 7 - Application 6 - Presentation crypto gateway 5 - Session 4 - Transport Router 3 - Network 2 – Data Link Switch, Hub , Repeater 1 - Physical Hub, Splitter  Network Equipment Classification (3/3)  Based on Certification: 1. Certified 2. Uncertified  By Filtering Capability: 1. Without Filtering: Equipment that lacks or does not support filtering functionalities for network traffic. 2. According to Signs in Traffic: Equipment capable of filtering network traffic based on specific indicators or signatures present in the data packets. 3. Decision Criteria for Filtering: Criteria used by equipment to make decisions regarding network Network Equipment Classification (4/4) According to the data transmission medium:  Wired  Wireless Coaxial cable twisted pair Optical fiber Wi-Fi Communication Modes  Duplex - a method of communication employing transceiver devices such as modems, network cards, walkie-talkies, telephones, etc.  A device that implements duplex communication can both transmit and receive information simultaneously. Transmission and reception occur concurrently through two physically separated communication channels, utilizing separate conductors, differing frequencies, etc., except for time separation (sequential transmission).  Duplex communication is sometimes referred to as full duplex  Communication Modes In addition to duplex, there are two other communication modes: half-duplex and simplex.  In half-duplex mode, a device can either transmit or receive information at any given time but not both simultaneously.  In simplex mode, equipment can only transmit information in one direction.  According to ANSI, the simplex communication scheme allows signals to be transmitted continuously in only one direction.  According to ITU-T, the simplex communication scheme allows signals to be transmitted in only one direction at any given time. However, at a different point in time, the signals may be transmitted in the opposite direction. This type of communication is commonly referred to as half-duplex communication. Communication Modes  Duplex radio communication enables simultaneous two-way communication. In this mode, the total speed of information exchange over the communication channel can reach its maximum capacity.  Half-duplex is a mode where, unlike duplex, transmission occurs over a single communication channel in both directions, but with time separation (only one direction of transmission occurs at any given moment). The total rate of information exchange over the communication channel in this mode is half the maximum capacity compared to duplex.  This mode is commonly employed in networks using coaxial cables or when hubs serve as active equipment. Depending on the hardware, simultaneous reception/transmission in half-duplex mode might either be physically impossible (for instance, due to utilizing the same circuit for both receiving and transmitting in walkie-talkies) or may result in collisions.  Collision Domain  In Ethernet technology, irrespective of the physical layer standard employed, the concept of a collision domain exists.  A collision domain refers to a specific part of an Ethernet network where all nodes contend for a shared transmission medium. Consequently, each node within this segment can potentially collide with any other node present in this section of the network.  In simpler terms, it denotes a network segment operating at the link layer of the OSI model, allowing only one node to transmit a frame at any given time. Collisions occur due to either delays in frame propagation between stations or simultaneous transmission attempts, necessitating special handling and resulting in reduced network performance.  The likelihood of collisions increases as the number of nodes within this segment grows. To mitigate collisions, switches are utilized to segregate or separate the collision domains. Network Devices and Collision Domain Network devices functioning at the data link layer of the OSI model possess the capability to either expand or restrict the collision domain. The available options are as follows:  OSI layer 1 devices (such as hubs and repeaters) solely relay any signal received from the transmission medium, thereby enlarging the collision domain.  OSI layer 2 devices (such as bridges and switches) contribute to a shared collision domain.  The collision domain remains separate when connecting to a switch port in half- duplex mode or establishing a point-to-point connection between two network adapters. In these scenarios, collisions are eliminated in full-duplex mode. Related terminologies  Propagation Delay refers to the time taken for the transmission of a segment, known as the slot time. This duration equals 512 bits for speeds up to 100 Mbps and 4096 bits for speeds of 1000 Gbps. Within this time interval, collisions can potentially occur. It is calculated based on the signal speed along the wire and the transmission rate. For 10 Mbps Ethernet, the propagation delay stands at 51.2 microseconds (µs), while for 100 Mbps, it is 5.12 µs. Most network equipment manages transmission collisions solely during the propagation delay.  Belated Collision signifies a collision occurring after the propagation delay. Such collisions typically go undetected by most network equipment, resulting in dropped frames.  The Collision Domain Diameter denotes the maximum signal propagation delay between any two stations. This measurement is usually defined in units of time and equates to twice the minimum frame length for a specific Ethernet type. It's calculated using the formula D = 2 * * 0.1 µs. Splitter  An ADSL filter is a combined electrical filter designed for channel frequency separation. It is employed in telecommunications networks when utilizing a shared physical environment, such as a subscriber line, for various communication purposes. The filter enables an ADSL modem and a telephone/fax machine to independently and concurrently operate on the same telephone line.  The ADSL splitter serves the purpose of segregating voice frequencies (ranging from 0.3 kHz to 3.4 kHz) from the frequencies utilized by the ADSL modem (ranging from 26 kHz to 1.4 MHz). This separation ensures that the modem and the telephone set do not interfere with each other, eliminating mutual influence.  ADSL, which stands for Asymmetric Digital Subscriber Line, refers to a modem technology that asymmetrically distributes the available bandwidth of the channel between outgoing and incoming traffic. Repeater  A repeater is network equipment built to extend the reach of a network connection, extending it beyond one segment or linking two branches by retransmitting the electrical signal "one to one."  Two types exist: 1. Single port repeaters 2. Multiport repeaters.  In the OSI model, repeaters function at the physical layer. They regenerate and amplify signals, working to maintain signal integrity and extend the network's reach. Repeater Repeater Hub  A hub, also known as a network hub, functions as a repeater in a network. While its physical function remains the same, it rebroadcasts the restored signal to all active ports except the one from which the signal originated.  For instance, consider a network with 5 computers connected via a hub. When transferring data from the fifth computer to the first, the data traverses through all the computers on the network. This accessibility allows any computer to access the data, consequently increasing the network load. As more computers are linked, the connection slows down, amplifying the network load.  In contemporary times, the production and usage of hubs have significantly decreased. Hub  Characteristics of Network Hubs: 1. Number of Ports: Hubs feature connectors to link network lines, determining the number of devices that can be connected simultaneously. 2. Transfer Rate: Measured in Mbps (Megabits per second), the speed of hubs can be automatically adjusted to the lowest used speed or configured through jumpers or switches. 3. Availability of Ports for Different Ethernet Cables: Hubs may offer ports for connecting various types of Ethernet cables, including coaxial or optical cables, providing flexibility in network connectivity options. The difference between Repeaters and Hubs  The distinction between Repeaters and Hubs lies in their functionalities despite their similar roles. Repeaters typically possess two cable connectors, resulting in significantly lower latency. They do not require signal concentration and redistribution to other outputs. The difference between Repeaters and Hubs The hub is considered a logical evolution of the repeater, integrating additional features offered by various manufacturers:  Segment Integration: Hubs often possess the capability to merge network segments utilizing different physical media, such as coaxial cable and twisted pair, allowing for versatile connectivity within the network.  Automatic Port Shutdown: Some hubs come equipped with functionality that automatically disables ports upon detecting errors occurring within those specific ports. This feature helps in maintaining network stability and preventing further issues.  Backup Link Support: Certain hubs are designed to support backup links, ensuring network continuity even if primary links encounter failures. This feature provides redundancy, allowing the network to remain operational during link disruptions by seamlessly switching to alternative backup connections. Bridge Network Bridge:  Operates at the second layer (Data Link layer) of the OSI model.  Function: Unify segments or subnets within a network into a single network entity.  Frame Handling:  Examines destination MAC address when receiving a frame.  If the MAC address belongs to the same subnet as the bridge, the frame is broadcasted to the specific segment intended.  Takes no action if the frame does not belong to the given subnet, allowing it to pass through unaffected.  Types of Bridge The various types of bridges are categorized based on distinct product characteristics within the realm of "transparent" bridges. These classifications include: 1. Transparent Bridges: These bridges amalgamate networks with shared protocols at the channel and physical layers of the OSI model. 2. Translating Bridges: This type of bridge is designed to interconnect networks employing different protocols at the channel and physical layers, allowing for seamless communication between dissimilar protocol-based networks. 3. Encapsulating Bridges: These bridges facilitate connections between networks utilizing identical channel and physical layer protocols by passing them through networks that operate with different protocols. They act as intermediaries, enabling communication between networks with distinct protocol configurations. Bridge Functions The bridge performs the following functions:  Limits collision domains.  Delays frames addressed to a node in the sender's segment.  Restricts the propagation of erroneous frames between domains, including:  Dwarfs (frames smaller than the standard minimum length of 64 bytes).  Frames with CRC errors.  Frames marked with a "collision" signal.  Prolonged frames (larger than the standard allowable size). Switch  A switch (Network switch) - is a device specifically designed to interconnect multiple nodes within one or across several network segments. Operating at the data link (second) layer of the OSI model, switches are constructed using bridge technologies and are commonly perceived as multi-port bridges. Routers, situated at the OSI layer 3, are utilized for interconnecting multiple networks.  Switches are categorized as managed or unmanaged (the most basic form).  Advanced switches offer management capabilities at the network (third) layer of the OSI model. They are often labeled accordingly, such as "Layer 3 Switch" or abbreviated as "L3 Switch." These switches can be administrated through a web interface or a command-line interface (CLI).  Switch  The switch employs associative memory, storing a switching table in its memory. This table correlates the MAC address of each host to the corresponding port on the switch. Upon powering on, this table is initially empty, placing the switch in a learning mode. During this phase, incoming data from any port is disseminated to all other ports on the switch.  As frames are analyzed, the switch identifies the MAC address of the transmitting host and temporarily records it in the table. Consequently, if a frame arrives at one of the switch ports, addressed to a host already listed in the table, the frame will be exclusively transmitted through the specified port. Conversely, if the MAC address of the destination host isn’t associated with any switch port, the frame will be broadcasted to all ports except the one through which it was initially received.  It's important to highlight the switch's attributes of low latency (minimal delay) and high forwarding speed across each interface port. Switch Buffering Function: Enables temporary storage of frames for subsequent transmission to the intended address. Congestion Handling: Utilizes buffering when the destination port experiences congestion. Memory Buffer Methods: Port Buffering: Stores packets in queues tied to individual input ports. Transmission to the output port occurs after successful transmission of preceding frames, potentially causing delays for the entire queue. Shared Memory Buffering: Stores all frames in a common memory buffer used by all switch ports. Dynamic allocation of buffer memory based on specific port requirements allows frames to be dynamically allocated to output ports, facilitating transmission without queuing. Switch  The switch utilizes a port map to designate the destination for frame transmission. This map remains cleared only after the successful transmission of the frame.  As the buffer memory is shared, the frame size isn't restricted to a fraction dedicated to a specific port but is instead limited to the entire buffer size. This design allows larger frames to be transmitted with fewer losses, particularly significant in asymmetric switching scenarios. For instance, when a port with a bandwidth of 100 Mbps needs to send packets to a 10 Mbps port. The difference between a Switch and a Hub  Unlike a hub (OSI layer 1), which distributes traffic from one connected device to all others, the switch transmits data only directly to the recipient (the exception is broadcast traffic to all network nodes and traffic for devices for which the outgoing port of the switch is unknown). This improves network performance and security by removing the need (and ability) for the rest of the network to process data that was not intended for them. Router Function: Specialized computer that forward packets between diverse network segments based on rules and routing tables. Network Integration: Links heterogeneous networks of varying architectures by utilizing network topology information and administrator- defined rules for packet forwarding decisions. OSI Layer: Operates at the "network" layer (Layer 3) of the OSI network model, contrasting with switches and hubs operating at lower layers. Traffic Management: Reduces network traffic by segregating into collision or broadcast domains and filtering packets. Primarily employed to interconnect networks of different types, often incompatible in architecture and protocols. Router Routing Process: Routers typically use the destination address in the packet header to determine the forwarding path via the routing table. If no route is specified, the packet is dropped. Alternate Forwarding Methods: Routers can also determine packet forwarding paths using the source address, upper layer protocols, and additional data within network layer packet headers. Additional Router Functions: Address Translation: Routers can translate sender and recipient addresses. Traffic Filtering: Implementation of rules to restrict access to transit data flows. Encryption/Decryption: Capabilities to encrypt or decrypt transmitted data for enhanced security.  Router Routing Table Compilation Methods:  Static Routing:  Manual entry and modification of records in the routing table.  Requires administrator intervention for topology changes.  Offers stability and demands minimal router hardware resources.  Dynamic Routing:  Automatic table updates via routing protocols like RIP, OSPF, IGRP, EIGRP, IS-IS, BGP, etc.  Builds optimal paths based on criteria such as intermediate nodes, channel bandwidth, and data transfer delay.  Criteria for optimal routes depend on routing protocol and router configuration.  Automatically maintains up-to-date routing tables and calculates best routes as per the current network topology.  Repeater, switch and router Switching Switching in Computer Networks:  Switching involves connecting network subscribers through transit nodes, utilizing three different methods, each with specific parameters impacting latency and transmission reliability. 1. Store and Forward: 1. Reads entire frame information, checks for errors, selects switching port, then forwards the frame. 2. Ensures error detection but increases latency due to processing. 2. Cut-Through: 1. Reads only destination address in the frame before switching. 2. Reduces transmission delays but lacks error detection methods. 3. Fragment-Free or Hybrid: 1. Modified version of cut-through mode, filtering collision fragments (analyzes the first 64 bytes for errors). 2. Provides a balance between reduced delays and error checking.  Switch Decision Delay: Additional delay resulting from the time a frame enters and exits the switch port. Contributes to determining the overall delay within the switch. Switching Symmetry and Asymmetry in Switching: 1. Symmetric Switch: 1. Provides switched connections between ports with identical bandwidth capacities (e.g., all ports at 10 Mbps or 100 Mbps). 2. Asymmetric Switch: 1. Facilitates switched connections among ports with varying bandwidth capacities (e.g., combination of ports at 10 Mbps / 100 Mbps and 1000 Mbps). 3. Asymmetrical Switching: 1. Applied in scenarios with heavy client-server network traffic. 2. Allocates higher bandwidth to the switch port connected to the server to prevent congestion due to simultaneous communication of multiple users with the server. Network Adapter Network Adapter (Network Card / Ethernet Adapter): Definition: Additional device enabling computer interaction with other network devices. Constructive Implementations: Internal (Domestic): Separate boards inserted into designated slots. External: Connects via various interfaces, predominantly used in laptops. Integrated: Built directly into the motherboard itself. Access point Wireless Access Point (WAP):  Wireless base station facilitating access to an existing network (wireless or wired) or establishing a new wireless network.  Primarily used to grant access to mobile devices (e.g., laptops, printers) onto a fixed local network. WiFi Repeater:  Functions as a Wi-Fi amplifier by repeating signals to expand an existing wireless access network.  Receives Wi-Fi signals and extends their transmission range. Standards for Access Points:  Wi-Fi (IEEE 802.11) and Bluetooth are the most prevalent standards. Gateway Crypto Gateway (Cryptographic Gateway, VPN Gateway, Crypto Router):  Hardware and software system providing cryptographic protection for data, voice, and video traffic.  Utilizes packet encryption using IPsec AH and/or IPsec ESP protocols during connection establishment.  Designed to: Safeguard an organization's information security. Shield information networks from intrusions within data transmission networks (e.g., Internet). Ensure confidentiality during information transmission over open communication channels (VPN). Facilitate secure user access to public network resources.  Crypto Gateway Crypto gateway provides the basic functionality of a modern VPN device Key Functionality of Crypto Gateway in VPN:  Ensures confidentiality and integrity of IP packet flows.  Hides network topology through secure traffic encapsulation in a tunnel.  Provides transparency for Network Address Translation (NAT).  Authenticates network nodes and users.  Unifies security policy for mobile and "internal" users, enabling dynamic configuration of corporate IP addresses for remote VPN users. Crypto Gateway vs. Conventional VPN Routers:  Operates based on the IPSec protocol for information protection over communication channels.  Differentiates from conventional VPN routers by employing algorithms meeting cryptographic standards.  Available in the domain of both VPN devices and Unified Twisted pair Cable  Type of communication cable consisting of one or more pairs of insulated conductors twisted together.  Covered with a plastic sheath.  Utilized in telecommunications and computer networks as a physical signal transmission medium across various technologies like Ethernet, Token Ring, and USB.  Widely employed in constructing wired (cable) local networks due to its cost- effectiveness and simple installation process. Fiber Optic Communication Utilizes electromagnetic radiation in the optical (near infrared) range for information transmission. Employs fiber optic cables as guide systems. Offers high throughput due to high carrier frequency and extensive multiplexing capabilities, measured in terabits per second. Low attenuation of light enables long-distance transmission without amplifiers. Resistant to electromagnetic interference, ensuring a reliable signal transmission. Difficult for unauthorized access due to technical complexity in intercepting signals transmitted over optical cables without detection. Fiber Optic Communication  Widely adopted across various sectors: Computer systems On-board systems in space, aircraft, and ships Long-distance information transmission systems  Examples include the Western Europe - Japan fiber-optic communication line, a significant portion traversing Russia.  Growing total length of submarine fiber-optic communication lines connecting continents indicates increasing global deployment and reliance on this technology. Coaxial Cable Electrical cable comprising a central conductor and a surrounding screen separated by insulating material or an air gap. Primarily used for transmitting radio frequency electrical signals. Distinct from shielded wire for direct Coaxial cable device current and low-frequency signals due to 1 - Inner conductor; a more uniform cross-section along the 2 - Insulation; 3 - External conductor longitudinal axis and the use of superior (Screen); materials for conductors and insulation. 4 - Shell. Invented and patented in 1880 by British physicist Oliver Heaviside. Firewall  Component of a computer network, comprising software or a combination of software and hardware.  Function: Controls and filters network traffic based on predetermined rules and criteria.  Manages incoming and outgoing data, regulating access to ensure network security and compliance with specified rules. IDS/IPS Intrusion Detection System (IDS):  Software or hardware tool identifying unauthorized access or control of computer systems or networks, particularly via the Internet.  Provides an additional layer of protection for computer systems by detecting intrusion attempts. Intrusion Prevention System (IPS):  Software or hardware network and computer security system detecting and automatically defending against intrusions or security breaches.  An extension of IDS, where IPS monitors real-time activity and swiftly takes action to prevent attacks, distinguishing it from IDS which primarily tracks attacks but doesn't actively intervene. IDS/IPS Have Questions?