Basic of Wired Networks: Ethernet Basics - PDF

Basic of Wired Networks TECM 120 ‫أساسيات الشبكات السلكية‬ 120 ‫تقم‬ Prepared by : Ethernet Basics Dr Nour Ismail Assistant Profess...

Basic of Wired Networks TECM 120 ‫أساسيات الشبكات السلكية‬ 120 ‫تقم‬ Prepared by : Ethernet Basics Dr Nour Ismail Assistant Professo Objectives Describe the Ethernet Switching Logical network topology component Determines connection creation between nodes Is the process of transferring data from one device to another in a network, or from one network to another, using specific devices called switches. Works at the Data Link Layer of the OSI Model Three methods Circuit switching Packet switching Multiprotocol label switching  Circuit Switching Connection established between two network nodes Before transmitting data Dedicated bandwidth Data follows same initial path selected by switch Monopolizes bandwidth while connected Resource wasted Uses Live audio, videoconferencing Traditional telephone calls *Bandwidth is the maximum capacity of a link to deliver data via a connection in a given amount of time , it is typically defined as the number of bits, kilobits, megabits, or gigabits that may be sent in one second. Packet Switching Most popular Breaks data into packets before transporting Packets Travel any network path to destination Find fastest circuit available at any instant Need not follow each other Need not arrive in sequence Reassembled at destination Requires speedy connections for live audio, video transmission Packet Switching MPLS (Multiprotocol Label Switching) MPLS is a protocol designed to get packets of data to their destinations quickly and efficiently , because it sends data straight to its destination. Enables multiple types of Layer 3 protocols: To travel over any one of several Layer 2 protocols Most often supports IP Common use Layer 2 WAN protocols Offers potentially faster transmission than packet- or circuit-switched networks  Ethernet Most popular networking technology used on modern LANs Benefits Flexible Can run on various network media Excellent throughput Reasonable cost All variations Share common access method CSMA/CD *Throughput is the actual rate at which data is successfully transmitted over a network or channel within a specific period. CSMA/CD (Carrier Sense Multiple Access with Collision Detection) Network access method Controls how nodes access communications channel Enable each computer to listen to the connection before delivering data across the network. Necessary to share finite bandwidth Carrier sense Multiple Access with Collision Detection Carrier Sense refers to an Ethernet NIC listening and waiting until no other nodes are transmitting data. Multiple Access refers to several nodes accessing the same network media. Collision Detection refers to what happens when two nodes attempt a transmission at the same time. CSMA/CD (cont’d.) Collision Two nodes simultaneously: Check channel, determine it is free, begin transmission Collision detection Manner nodes respond to collision Requires collision detection routine Enacted if node detects collision Jamming NIC issues 32-bit sequence Indicates previous message faulty Ethernet Standards for Copper Cable IEEE Physical layer standards Specify how signals transmit to media Differ significantly in signal encoding Affect maximum throughput, segment length, wiring requirements Ethernet Standards for Copper Cable 10Base-T 10 represents maximum throughput: 10 Mbps Base indicates baseband transmission T stands for twisted pair Two pairs of wires: transmit and receive Full-duplex transmission Follows 5-4-3 rule of networking Five network segments Four repeating devices Three populated segments maximum Network+ Guide to Networks, 6 th Edition Figure 5-14 A 10Base-T network Courtesy Course Technology/Cengage Learning Ethernet Standards for Copper Cable 100Base-T (Fast Ethernet) Similarities with 10Base-T Baseband transmission, star topology, RJ-45 connectors Supports three network segments maximum Connected with two repeating devices 100 meter segment length limit between nodes Figure 5-15 A 10Base-T network Courtesy Course Technology/Cengage Learning Ethernet Standards for Copper Cable 1000Base-T (Gigabit Ethernet) 1000 represents 1000 Mbps Base indicates baseband transmission T indicates twisted pair wiring Four pairs of wires in Cat 5 or higher cable Transmit and receive signals Maximum segment length: 100 meters, one repeater Ethernet Standards for Copper Cable 10GBase-T Pushing limits of twisted pair Requires Cat 6, 6a, or 7 cabling Maximum segment length: 100 meters Benefits Very fast data transmission Cheaper than fiber-optic Uses Connect network devices Connect servers, workstations to LAN Ethernet Standards for Fiber-Optic Cable 100Base-FX (Fast Ethernet) 100-Mbps throughput, baseband, fiber-optic cabling Multimode fiber containing at least two strands Half-duplex mode One strand receives; one strand transmits 412 meters segment length Full duplex-mode Both strands send and receive 2000 meters segment length One repeater maximum Ethernet Standards for Fiber-Optic Cable 1000Base-LX (1-Gigabit Ethernet) 1000: 1000-Mbps throughput Base: baseband transmission LX: reliance on 1300 nanometers wavelengths Longer reach than any other 1-gigabit technology Single-mode fiber: 5000 meters maximum segment Multimode fiber: 550 meters maximum segment One repeater between segments Excellent choice for long backbones Ethernet Standards for Fiber-Optic Cable 1000Base-SX (1-Gigabit Ethernet) Differences from 1000Base-LX Multimode fiber-optic cable (installation less expensive) Uses short wavelengths (850 nanometers) Maximum segment length dependencies Fiber diameter, modal bandwidth used to transmit signals Ethernet Standards for Fiber-Optic Cable 1000Base-SX (cont’d.) Modal bandwidth measurement Highest frequency of multimode fiber signal (over specific distance) MHz-km 50 micron fibers: 550 meter maximum length 62.5 micron fibers: 275 meter maximum length One repeater between segments Best suited for shorter network runs 10-Gigabit Fiber-Optic Standards Extraordinary potential for fiber-optic cable Pushing limits 802.3ae standard Fiber-optic Ethernet networks Transmitting data at 10 Gbps Several variations Common characteristics Star topology, allow one repeater, full-duplex mode Differences Signal’s light wavelength; maximum allowable segment length 10-Gigabit Fiber-Optic Standards (cont’d.) 10GBase-SR and 10GBase-SW 10G: 10 Gbps Base: baseband transmission S: short reach Physical layer encoding R works with LAN fiber connections W works with SONET fiber connections Multimode fiber: 850 nanometer signal transmission Maximum segment length Depends on fiber diameter 10-Gigabit Fiber-Optic Standards (cont’d.) 10GBase-LR and 10GBase-LW 10G: 10 Gbps Base: baseband transmission L: long reach Single-mode fiber: 1310 nanometer signal transmission Maximum segment length 10,000 meters 10GBase-LR: WAN or MAN 10GBase-LW: SONET WAN links 10-Gigabit Fiber-Optic Standards (cont’d.) 10GBase-ER and 10GBase-EW E: extended reach Single-mode fiber Transmit signals with 1550 nanometer wavelengths Longest fiber-optic segment reach 40,000 meters (25 miles) Best suited for WAN use Summary of Common Ethernet Standards Table 5-1 Common Ethernet standards Courtesy Course Technology/Cengage Learning Figure 5-16 Multiple types of Ethernet on a WAN Courtesy Course Technology/Cengage Learning Ethernet Frames Four types Ethernet_802.2 (Raw) Ethernet_802.3 (Novell proprietary) Ethernet_II (DIX) Ethernet_SNAP Frame types differ slightly Using and Configuring Frames Ensure all devices use same, correct frame type Node communication Ethernet_II used today Frame type configuration Specified using NIC configuration software NIC autodetect Importance Know frame type for troubleshooting Frame Fields Common fields 7-byte preamble, 1-byte start-of-frame delimiter SFD (start-of-frame delimiter) identifies where data field begins 14-byte header 4-byte FCS (frame check sequence) Frame size range: 64 to 1518 total bytes Larger frame sizes result in faster throughput Ethernet_II (DIX) Developed by DEC, Intel, Xerox (abbreviated DIX) Contains 2-byte type field Identifies the Network layer protocol Most commonly used on contemporary Ethernet networks Figure 5-17 Ethernet II (DIX) frame Courtesy Course Technology/Cengage Learning PoE (Power over Ethernet) Supplying electrical power over Ethernet connections Two device types PSE (power sourcing equipment) The device that supplies the power PDs (powered devices) Devices that receive power from the PSE Requires Cat 5 or better copper cable Connectivity devices must support PoE PoE (cont’d.) Figure 5-18 PoE capable switch Figure 5-19 PoE adapters Courtesy D-Link North Courtesy D-Link North America America Summary Switching Manages packet filtering, forwarding Ethernet Cabling specifications, data frames, PoE