Physical Transmission Options Chapter 3

Learning Objectives Describe the functions of the principal networking standards organizations Describe the various kinds of network media, including coaxial, twisted-pair, and fiber-optic media, and identify which to use in a given network configuration Describe the basics of wireless communications continued…

Learning Objectives Discuss high-speed technologies for twisted-pair and fiber-optic cable Compare packet and cell implementations and the interfaces used by each Explain WAN carrier types for point-to-point, T-carrier, SONET, ISDN, and wireless topologies

Network Standards Organizations Help ensure that equipment from different manufacturers can be integrated Key role in growth of networks and network equipment

Network Standards Organizations ANSI American National Standards Institute IEEE Institute of Electrical and Electronics Engineers ITU International Telecommunications Union ISO International Organization for Standardization ISOC Internet Society IETF Internet Society and the Internet Engineering Task Force EIA/TIA Electronic Industries Alliance and the Telecommunications Industry Association

ANSI Established in 1918 Standards for wide range of products Computer industry standards: Screen-display attributes Digital telecommunications Fiber-optic cable transmissions

IEEE International organization of scientists, engineers, technicians, and educators Develops networking standards for network cabling and data transmissions 802 standards

ITU Sets telecommunications standards for modem and WAN communications International organization

ISO Establishes communications and networking standards Known for its contributions to network protocol standards International organization

ISOC and IETF ISOC Sponsors conferences and publications and oversees Internet standards Nonprofit international organization Supporter of Internet Corporation for Assigned Names and Numbers (ICANN) IETF Arm of ISOC that works on Internet-related technical issues such as routing

EIA and TIA EIA Network cabling standards and electrical interface standards TIA Standards body within EIA that develops telecommunications and cabling standards Structured wiring, horizontal cabling, backbone cabling Wiring closet configurations

Physical Transmission Options for LANs and WANs Media types Interface types WAN carrier types

Communications Media Types Coaxial cable Based on copper wire construction Twisted-pair cable Fiber-optic cable Glass (usually), or plastic Wireless technologies Radio or microwaves

Factors to Consider When Choosing a Medium Data transfer speed Use in specific network topologies Distance requirements Cable and cable component costs Additional network equipment that might be required Flexibility and ease of installation Immunity to interference from outside sources Upgrade options

Coaxial Cable Copper core surrounded by insulation Insulation surrounded by another conducting material, which is covered by an outer insulating material Types Thick coax cable (thickwire or thicknet) Thin coax cable

Thick Coax Cable

Connecting to Thick Coax Cable

Thick Coax Cable Properties

Thin Coax Cable Attaches to a bayonet nut connector (BNC)

Thin Coax Cable Properties

Twisted-Pair Cable Flexible cable that contains pairs of insulated copper wires that are twisted together for reduction of EMI and RFI and covered with an outer insulating jacket Typically used on LANs to bring network to desktop Connects to network devices with RJ-45 plug-in connectors

Twisted-Pair Cable

Types of Twisted-Pair Cable Shielded twisted-pair (STP) cable Pairs of insulated wires that are twisted together, surrounded by shielding material for added EMI and RFI protection, all inside a protective jacket Unshielded twisted-pair (UTP) cable No shielding material between pairs of insulated wires twisted together and cable’s outside jacket

STP and UTP Cable

Twisted-Pair Cable Standards

Twisted-Pair Cable Types for Token Ring Applications

Properties of Twisted-Pair Cable

Properties of Twisted-Pair Cable

Token Ring Design Specs

Fiber-Optic Cable Glass or plastic fiber core inside protective cladding material, covered by plastic PVC outer jacket Usually uses infrared light for signal transmission Used to connect networks on LANs and to connect LANs into WANs

Fiber-Optic Cable Advantages Disadvantages Able to sustain transmissions over long distances due to high bandwidth and low attenuation No EMI or RFI problems Difficult to place unauthorized taps Disadvantages Very fragile Relatively expensive Requires specialized training to install

Fiber-Optic Cable Modes Single-mode Multimode Step index Graded index

Properties of Single-Mode Fiber-Optic Cable

Properties of Multimode Fiber-Optic Cable

Hybrid Fiber/Coax (HFC) Cables Single cable sheath containing a combination of fibers and copper cables in different combinations for different implementations Full HFC system can deliver: Plain Old Telephone Service (POTS) Up to 37 analog TV channels Up to 188 digital TV channels Up to 464 digital point channels High-speed, two-way digital data link for PCs

High-Speed Technologies for Twisted-Pair and Fiber-Optic Cable Fast Ethernet Gigabit Ethernet 10 Gigabit Ethernet

Fast Ethernet Ethernet communications at speeds up to 100 Mbps as defined under the: 802.3u standard More commonly used Based on CSMA/CD 802.12 standard Uses demand priority

The IEEE 802.3u Standard

The IEEE 802.12 Standard

Gigabit Ethernet Provides even faster network communications Particularly important for backbone architectures

Gigabit Ethernet Specifications

10 Gigabit Ethernet Positioned to become popular LAN and WAN alternative; promises very high-speed communications Does not use CSMA/CD as the transmission method

10 Gigabit Ethernet Specifications

Wireless Communications Transmit signal through air or atmosphere Good alternative when cable is not physically or economically feasible Can experience interference from other signals using same media Types available Radio waves and infrared signals (short-distance) Microwave and satellite (long-distance)

Data Interface Types Data is transported on networks in packets or cells Each type of transport requires specialized interfaces for physical network connections

Packet Transmission Used at lower bandwidth installations Most commonly used to carry data on LANs Requires transceivers, appropriate cable interfaces, and network drivers Timing information for multiple packet transfers Packets are physically transported on a network via network interface card (NIC) Packets contain variable amount of data in multiples of eight bits

Generic Packet Format Format determined by protocol used on network

Cell Transmission Used for very high-bandwidth implementations Enables high-speed communications between LANs and on WANs Requires transceivers, appropriate cable interfaces, and network drivers Cells contain fixed amount of data formatted to be transmitted at high speeds Primarily used in Asynchronous Transfer Mode (ATM)

Generic Cell Format

WAN Carrier Types Point-to-point T-carrier SONET (synchronous optical network) ISDN (Integrated Services Digital Network)

Point-to-Point Two stations communicate through public dial-up or leased lines

T-Carrier Normally available through telecommunications carriers Typically come out of channel banks at telecommunications company Five types of channel banks: D-1 through D-4 and Digital Carrier Trunk

T-Carrier DS-x Relates to OSI Physical layer, which influences electrical transmission T-x Relates to Data Link layer, which addresses protocol and data-formatting issues

T-Carrier Switching Techniques Time division multiple access (TDMA) Combination of TDMA and statistical multiple access Fast packet technology Multiplexer

T-Carrier Connections Digital access cross-connects (DACS) DS-1 (T-1) connectivity Combined DS-0 or fractional connectivity Single DS-0 channels Combination channel service unit (CSU) and data service unit (DSU)

Connecting with a CSU/DSU

SONET Uses single-mode and multimode fiber-optic cable and communications based on T-3 services Allows for high-speed data transmission, enabling delivery of voice, data, and video Converts electrical-based STS-x signal to optical-based signal (optical carrier or OC)

SONET STS-1 Frame

SONET STS-x and OC-x Transmission Rates

ISDN WAN technology for delivering voice, data, and video services over telephone lines, using a combination of channels Physical line is a POTS or T-1 (twisted-pair or fiber-optic), with ISDN equipment at the telco and customer Methods of placing digital signals on network Time-compression multiplexing (TCM) Echo cancellation

Chapter Summary Standards organizations that influence network transmission techniques and media Communications cabling media High-speed technologies Fast Ethernet Gigabit Ethernet 10 Gigabit Ethernet continued…

Chapter Summary How data is transported by using packets and cell formats Specialized carrier methods Point-to-point T-carrier SONET ISDN Wireless transmission