CIS 1140 Network Fundamentals

CIS 1140 Network Fundamentals Chapter 3 Transmission Basics and Networking Media Collected and Compiled By JD Willard MCSE, MCSA, Network+, Microsoft IT Academy Administrator Computer Information Systems Instructor Albany Technical College

Attention: Accessing Demos • This course presents many demos. • The Demosrequire that you be logged in to the Virtual Technical College web site when you click on them to run. • To access and log in to the Virtual Technical College web site: • To access the site type www.vtc.com in the url window • Log in using the username: CIS 1140 or ATCStudent1 • Enter the password: student (case sensitive) • If you should click on the demo link and you get an Access Denied it is because you have not logged in to vtc.com or you need to log out and log back in. • If you should click on the demo link and you are taken to the VTC.com web site page you should do a search in the search box for the CompTIA Network+ (2009 Objectives) Course and run the video from within that page.

Objectives • Explain basic data transmission concepts, including full duplexing, attenuation, and noise • Describe the physical characteristics of coaxial cable, STP, UTP, and fiber-optic media • Compare the benefits and limitations of different networking media • Explain the principles behind and uses for serial connector cables • Identify wiring standards and the best practices for cabling buildings and work areas

Transmission Basics • In data networking, transmit means to issue signals to the network medium • Transmission refers to either the process of transmitting or the progress of signals after they have been transmitted • Transceiver • Transmits and receives signals Cabling Basics Demo Cabling Demo

Analog and Digital Signals • Information transmitted via analog or digital signals • Signal strength proportional to voltage • In analog signals, voltage varies continuously and appears as a wavy line when graphed over time • Wave’s amplitude (the height of the wave) is a measure of its strength at given point in time • Frequency: number of times wave’s amplitude cycles from starting point, through highest amplitude and lowest amplitude, back to starting point over a fixed period of time • Measured in Hz • Wavelength: distance between corresponding points on a wave’s cycle • Phase: progress of a wave over time in relationship to a fixed point • Analog transmission susceptible to transmission flaws such as noise

An example of an analog signal • Analog signal benefit over digital • More variable • Convey greater subtleties with less energy • Drawback of analog signals • Varied and imprecise voltage • Susceptible to transmission flaws

Analog and Digital Signals • Digital signals composed of pulses of precise, positive voltages and zero voltages • Positive voltage represents 1 • Zero voltage represents 0 • Binary system: uses 1s and 0s to represent information • Easy to convert between binary and decimal • Bit: a single binary signal • Byte: 8 bits • Typically represents one piece of information • Overhead: describes non-data information that must accompany data for a signal to be properly routed and interpreted

Transmission Direction: Simplex, Half-Duplex, and Duplex • Simplex transmission: signals may travel in only one direction (TV or Radio) • Half-duplex transmission: signals may travel in both directions over a medium • Only one direction at a time (Walkie Talkies or Intercom System) • Full-duplex or duplex: signals free to travel in both directions over a medium simultaneously (Telephone) • Used on data networks • Channel: distinct communication path between nodes • May be separated logically or physically Full Duplex vs Half Duplex Demo

Transmission Direction: Multiplexing • Multiplexing: transmission form allowing multiple signals to travel simultaneously over one medium • Channel logically separated into subchannels • Multiplexer (mux): combines multiple signals • Sending end of channel • Demultiplexer (demux): separates combined signals and regenerates them in original form • Receiving end of channel

Relationships Between Nodes • Point-to-point transmission involves only one transmitter and one receiver. • Point-to-multipoint transmission involves one transmitter and multiple receivers. • Broadcasts involve one transmitter and multiple, undefined receivers • Nonbroadcast point-to-multipoint transmission issues signals to multiple, defined recipients

Throughput and Bandwidth • Throughput: measure of amount of data transmitted during given time period • Measured in bits per second, kilobits per second, megabits per second etc. • Probably most significant factor in choosing transmission method • Limited by signaling and multiplexing techniques used in given transmission method • Transmission methods using fiber-optic cables achieve faster throughput than those using copper or wireless connections • Noise and devices connected to transmission medium can limit throughput • Bandwidth: difference between highest and lowest frequencies that a medium can transmit • Range of frequencies • Measured in Hertz or cycles • 1 Hertz is the measure of a signal from its starting point to it’s highest amplitude to it’s lowest amplitude and back to the starting point

Baseband and Broadband • Baseband: digital signals sent through direct current (DC) pulses applied to a wire • Requires exclusive use of wire’s capacity • Baseband systems can transmit one signal at a time • Half-duplex or duplex transmission • Example: Ethernet • Broadband: signals modulated as radiofrequency (RF) analog waves that use different frequency ranges • Does not encode information as digital pulses • Simplex transmission Communication Methods Demo

Transmission Flaws: Noise • Electromagnetic interference (EMI): waves emanating from electrical devices or cables • Radio frequency interference (RFI): electromagnetic interference caused by radiowaves • Crosstalk: signal traveling on a wire or cable infringes on signal traveling over adjacent wire or cable • Certain amount of signal noise is unavoidable • All forms of noise measured in decibels (dB)

Attenuation Attenuation can be described as the loss of signal strength as the signal flows away from it’s source. It is caused by resistance on electrical networks and by optical loss on fiber optic networks. An analog signal distorted by noise and then amplified A digital signal distorted by noise and then repeated

Latency • Delay between transmission and receipt of a signal • May cause network transmission errors • Many possible causes: • Cable length • Intervening connectivity device (e.g., modems and routers) • Round trip time (RTT): Time for packets to go from sender to receiver and back • Cabling rated for maximum number of connected network segments • Transmission methods assigned maximum segment lengths

Network Cables • A cable is the medium that provides the physical foundation for data transmission • Several types of cable are commonly used • Some networks use only one type of cable, while others employ several cable types • The type of cable chosen depends on: • The size of the network • The protocols being used • The network’s physical layout, or topology Network Transmission Media Demo New and Old Cables and Connectors Demo

Common Media Characteristics: Throughput • Probably most significant factor in choosing transmission method • Match networking needs with media characteristics • Limited by signaling and multiplexing techniques used in given transmission method • Transmission methods using fiber-optic cables achieve faster throughput than those using copper or wireless connections • Laws of Physics, noise, and devices connected to transmission medium can limit throughput

Cost • Precise costs difficult to pinpoint • Media cost dependencies • Existing hardware, network size, labor costs • Variables influencing final cost of implementing specific type of media • Installation cost • New infrastructure cost versus reuse • Maintenance and support costs • Cost of lower transmission rate affecting productivity • Cost of downtime • Cost of obsolescence

Noise Immunity • Noise distorts data signals • Distortion rate dependent upon transmission media • Fiber-optic: least susceptible to noise • Limit noise impact on network • Cable installation • Far away from powerful electromagnetic forces • Select media protecting signal from noise • Antinoise algorithms

Size and Scalability • Three specifications determine size and scalability of networking media: • Maximum nodes per segment • Depends on attenuation and latency • Maximum segment length • Depends on attenuation, latency, and segment type • After certain distance, signal loses strength • Cannot be accurately interpreted • Populated segment contains end nodes • Unpopulated: no end nodes • Also called link segment • Maximum network length • Sum of network’s segment lengths Media Distance and Speed Limitations (5:48)

Connectors and Media Converters • Connectors are the pieces of hardware that connect the wire to the network device. • Every medium requires a specific kind of connector • Affect costs • Installing and maintaining network • Ease of adding new segments or nodes • Technical expertise required to maintain network • Media converter: hardware enabling networks or segments running on different media to interconnect and exchange signals • Type of transceiver • Device that transmits and receives signals Copper wire-to-fiber media converter Converting Media (5:10)

Coaxial Cable Coaxial cable is an older technology that is usually implemented with a bus topology. It is not suitable for ring or star topologies because the ends of the cable must be terminated. It is composed of two conductors, which share a common axis, within a single cable. UTP, STP, and Coaxial Cabling (5:53)

Coaxial Cable Coaxial cable is built with the following components: • Two concentric metallic conductors: • The inner conductor, which carries data signals. It is made of copper or copper coated with tin. • The mesh conductor is a second physical channel that also grounds the cable. It is made of aluminum or copper coated tin. • The insulator, which surrounds the inner conductor, keeps the signal separated from the mesh conductor. It is made of PVC plastic. • The mesh conductor, which surrounds the insulator and grounds the cable. It is made of aluminum or copper coated tin. • The PVC sheath, which is the cable encasement. It surrounds and protects the wire. It is made of PVC plastic. Coaxial Cable Demo

Coaxial Cable Types The table below describes the different coaxial cable grades. When using coaxial cables, it is important to use cables with the same resistance (impedance) rating.

F-type connector Coaxial Connectors • Connectors: pieces of hardware connecting wire to network device • Every networking medium requires specific kind of connector BNC Connectors Demo

Coaxial Connectors AUI 10BASE5 vampire tap & transceiver

Coaxial Cable Networks • Thin Ethernet, Thinnet, or Black Ethernet: more flexible and easier to handle and install than Thicknet • 10BASE-2 Ethernet • Requires RG-58 A/U coaxial cable, BNC-T connectors • Each end of the cable segment must be terminated with a 50 ohm resistor • Conforms to the 5-4-3 Rule of network which states that a network can contain up to 5 cable segments, connected by 4 repeating devices, but only three of the cable segments can contain end nodes.

Coaxial Cable Networks • Thickwire Ethernet, Thicknet, Yellow Ethernet: original Ethernet medium • 10BASE-5 Ethernet Standard • Requires RG-8 coaxial cable, AUI connectors, Transceiver/Vampire Tap, and Drop cable. • Each end of the cable segment must be terminated with a 50 ohm resistor • Conforms to the 5-4-3 Rule of network which states that a network can contain up to 5 cable segments, connected by 4 repeating devices, but only three of the cable segments can contain end nodes.

Twisted-Pair Cable Twisted pair cables support a wide variety of fast, modern network standards. Twisted pair cabling is composed of the following components: • Two wires that carry the data signals (one conductor carries a positive signal; one carries a negative signal). They are made of 22 or 24 gauge copper wiring. • PVC or plenum plastic insulation surrounds each wire. Plenum cable is fire resistant and non-toxic. It must be used when wiring above ceiling tiles. PVC cable cannot be used to wire above ceilings because it is toxic when burned. • Two wires are twisted to reduce the effects of electromagnetic interference (EMI) and crosstalk. Because the wires are twisted, EMI should affect both wires equally and can be cancelled out. • The number of twists per meter or foot determines how resistant the pair will be to noise but increases attenuation • TIA/EIA 568 standard divides twisted-pair wiring into several categories • Level 1 or CAT 3, 4, 5, 5e, 6, 6e, 7 Cable Categories (3:34)

Twisted-Pair Cable • Advantages: • Is relatively inexpensive, easy to install, and capable of spanning significant distances before additional equipment is required • Can accommodate several different topologies, but is most often used in a star topology • Can handle the faster networking transmission rates in use today • Multiple wire pairs are bundled together in an outer sheath. Twisted pair cable can be classified according to the makeup of the outer sheath: • Shielded Twisted Pair (STP) has a grounded outer copper shield around the bundle of twisted pairs or around each pair. This provides added protection against EMI. • Unshielded Twisted Pair (UTP) does not have a grounded outer copper shield. UTP cables are easier to work with and are less expensive than shielded cables. UTP Cable Demo Twisted Pair Cabling and Connectors Demo

Shielded Twisted-Pair (STP) • Shielded Twisted-Pair (STP): • The cable consists of insulated wire pairs that are surrounded by a metal shielding, such as foil • The effectiveness of the shield depends on the environmental noise to which STP is subjected, the grounding mechanism, and the material, thickness, symmetry and consistency of the shielding • Barrier to external electromagnetic forces • Contains electrical energy of signals inside • STP is more expensive than UTP, but does provide better immunity to EMI and RFI STP cable STP Cable Demo

UTP (Unshielded Twisted-Pair) • Less expensive, less resistant to noise than STP • The cable contains color-coded pairs of insulated copper wires inside a plastic jacket • Each pair has a different number of twists per inch, depending on the grade, to help eliminate interference from adjacent pairs or cables • Categories: • CAT 3 (Category 3): up to 10 Mbps of data at 16 MHz • CAT 4 (Category 4): 16 Mbps throughput at up to 20 MHz • CAT 5 (Category 5): up to 1000 Mbps throughput at 100 MHz • CAT 5e (Enhanced Category 5): higher twist ratio 350 MHz • CAT 6 (Category 6): six times the throughput of CAT 5. Wires encased in foil. 250 MHz • CAT 6e (Enhanced Category 6): reduced attenuation and crosstalk. Capable of 550 MHz. • CAT 7 (Category 7): signal rates up to 1 GHz. Contains sheilding and uses different connectors.

Twisted Pair Connectors Copper Connectors (10:29)

Comparing STP and UTP Characteristics • Throughput: STP and UTP can both transmit data at 10, 100, and 1000 Mbps • Depending on grade of cabling and transmission method used • Cost: STP usually more expensive than UTP • Connector: Both use RJ-45 for data and RJ-11 for phones • Noise Immunity: STP more noise-resistant • Size and scalability: Max segment length for both is 100 meters • Maximum of 1024 nodes

Terminating Twisted Pair Cable • Patch cable • Relatively short cable • Connectors at both ends • Proper cable termination techniques • Basic requirement for two nodes to communicate • Poor terminations: • Lead to loss or noise • TIA/EIA standards • TIA/EIA 568A • TIA/EIA 568B

TIA/EIA 568A Series • In the T568A standard the green and green and white striped wire transmits data from the device, while the orange wire and the orange and white striped wire receives data from the network. TIA/EIA 568A standard terminations

TIA/EIA 568B Series • In the T568B standard the orange and orange and white striped wire transmits data from the device, while the green wire and the green and white striped wire receives data from the network. • It typically doesn’t matter which scheme you choose, but to avoid confusion and potential transmission errors you should ensure that you cable all wiring on your LAN according to one standard. TIA/EIA 568B standard terminations

Straight-Through Cable Crossover and Straight Through Cables (6:27)

Crossover Cable • Crossover cables are used to wire two computer’s network cards together without the use of a hub/switch or to wire two hubs/switches together through their data ports (stacking) • To create a crossover cable wire one end of the cable 568A and the other end 568B

Device Connection When connecting Ethernet devices, it is important that the transmit (Tx) wires from one device are matched with the receive (Rx) wires on the other device. To help understand how to connect devices together, be aware of the following: • Network interface cards in workstations and routers send data on the transmit pins and expect to receive data on the receive pins. • Between any two ports used for connecting devices to a hub or a switch, crossing is automatically performed within the hub or the switch. • Uplink ports on hubs and switches are not crossed.

Cable Type - Usage

Straight-through Patch Cable Assembly Instructions • Strip the cable jacket back about 3/4 of an inch from the end of the cable • Sort the pairs so they fit into the connector in the correct order • Insert the pairs into the connector • Crimp the pins with a crimp tool • Repeat for other end and test cable

Twisted Pair Wiring Tools • Termination tools • Wire cutter • Wire stripper • Crimping tool • After making cables: • Verify data transmit and receive Crimpers (3:36)

Fiber-Optic Cable To connect computers using fiber optic cables, you need two fiber strands. One strand transmits signals, and the other strand receives signals. Fiber optic cabling is composed of the following components: • Fiber-optic cable (fiber) • One or more glass or plastic fibers at its center (core) carries the signal • Cladding • The cladding maintains the signal in the center of the core as the cable bends. It is made of a different density of plastic or glass. • Kevlar strands • Give the cable strength and allow it to avoid stretching • A Plastic sheath covers the kevlar strands and protects the cladding and the core • Data transmission • Pulsing light sent from laser or light-emitting diode (LED) through central fibers A fiber-optic cable

Fiber-Optic Cable Fiber Optic Cable Demo

Fiber Optic Characteristics • Throughput • transmission rates exceed 10 Gigabits per second • Cost • most expensive of the transmission mediums • Connector • 10 different types of connectors • typically use ST, SC, LC, or MTRJ connectors • Noise immunity • unaffected by EMI, RFI, or crosstalk • Size and scalability • segment lengths vary from 150 to 40,000 meters • Suffers from optical loss • degradation of light signal after it travels a certain distance away from its source

Fiber Optic Cables • Transfers data through the core using multiple light rays • The core diameter is around 50 to 100 microns • Cable lengths are limited in distance • Common uses • Cables connecting router to a switch • Cables connecting server on network backbone • Transfers data through the core using a single light ray (the ray is also called a mode) • The core diameter is around 10 microns • Supports a large amount of data • Cable lengths can extend a great distance • Rarely used for shorter connections • Due to cost Multimode and Singlemode Fiber (4:46)

Fiber Optic Connectors Figure 3-34 SC (subscriber connector or standard connector) Figure 3-33 ST (straight tip) connector Figure 3-36 MT-RJ (mechanical transfer-register jack) connector Figure 3-35 LC (local connector) Fiber Connectors (4:36)

Fiber-Optic Converters • Required to connect multimode fiber networks to single-mode fiber networks • Also fiber- and copper-based parts of a network Single-mode to multimode converter Courtesy Omnitron Systems Technology

Figure 3-38 DB-25 connector Figure 3-37 DB-9 connector Serial Cables • Data transmission style • - Pulses issued sequentially, not simultaneously • RS-232 (Recommended Standard 232) • EIA/TIA standard • Physical layer specification • Signal voltage, timing, compatible interface characteristics • Connector types • RJ-45 connectors, DB-9 connectors, DB-25 connectors • RS-232 used between PC and router today • RS-232 connections • Straight-through, crossover, rollover

CIS 1140 Network Fundamentals