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Course Outline. Data Communications: Past to Future Understanding the Standards and Their Makers Introduction to Transmission Technologies Multiplexing and Switching Technologies Optical Networking Midterm Revision Physical Layer Protocols and Access Technologies (28/7/07)
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Course Outline • Data Communications: Past to Future • Understanding the Standards and Their Makers • Introduction to Transmission Technologies • Multiplexing and Switching Technologies • Optical Networking • Midterm Revision • Physical Layer Protocols and Access Technologies (28/7/07) • Data-link layer and Protocols (28/7/07) • LANs and Hi-speed LANs (4/8/07) • ISDN (11/8/07) • Frame Relay (18/8/07) • ATM (25/8/07) • Wireless LANs and Cellular Networks (1/9/07) • Common Protocols and Interfaces in the Upper Layers (TCP/IP) (8/9/07) • Presentation (15/9/07) NETE0510: Communication Media and Data Communications
NETE0510Physical Layer Protocols and Access Technologies Supakorn Kungpisdan supakorn@mut.ac.th NETE0510: Communication Media and Data Communications
Physical Media • Three major types of physical media • Copper • Twisted-pair, coaxial, twin-axial (twin-ax), broadband (used in CATV) • Fiber • Resistance to electromagnetic signals, not affected by crosstalk, interference, but require more protection • Air • Point-to-point wireless, wireless LAN, cellular, microwave, or satellite NETE0510: Communication Media and Data Communications
RS-232, ITU-T V.24/V.28 • EIA RS-232 (or EIA-232 or most recent TIA-232) are defined by the Electronic Industries Association (EIA) as synchronous interface standards for use with the physical layer • D-shaped 25-pin connector (DB25) DTE interface to voice-grade modems (DCE) • TIA: Telecommunications Industry Association • EIA: Electronic Industries Alliance • ITU V.24/V.28 is similar to RS-232 and provides the international version of the RS-232 standard • V.24 defines physical interface and V.28 defines electrical interface NETE0510: Communication Media and Data Communications
RS-232 NETE0510: Communication Media and Data Communications
RS-232 (cont’d) • The standard does not define bit rates for transmission, although the standard says it is intended for bit rates lower than 20 kbps. • Many modern devices can exceed this speeed (38.4 kbps and 57.6 kbps being common, and 115.2 kbps and 230.4 kbps making occasional appearances) while still using RS232 compatible signal levels. • In general, terminals have male connectors with DTE pin functions, and modems have female connectors with DCE pin functions • Full RS232 requires 25-pin connector, whereas only 22 pins are used. Since most devices, especially PC, use only a few signals, smaller connectors can be used, e.g. 9-pin connector(DB9) • More about RS232 • http://www.camiresearch.com/Data_Com_Basics/RS232_standard.html • http://www.taltech.com/resources/intro-sc.html NETE0510: Communication Media and Data Communications
RS-232 (cont’d) HW flow control NETE0510: Communication Media and Data Communications
Connector Shell (Shield) • Pin 1 is wired to the connector shell (shield) • The cable's shield is usually a foil blanket surrounding all conductors running the length of the cable and joining the connector shells. • Pin 1 of the EIA232 specification, called out as "shield", may be separate from the earth ground usually associated with the connector shells. NETE0510: Communication Media and Data Communications
25-pin RS232 Pinouts (Shield ground) NETE0510: Communication Media and Data Communications
Data Transmission NETE0510: Communication Media and Data Communications
9-pin RS232 Pinouts NETE0510: Communication Media and Data Communications
DB25-to-DB9 Adapter • Use this to adapt a 25-pin COM connector on the back of a computer to mate with a 9-pin serial DCE device, such as a 9-pin serial mouse or modem. NETE0510: Communication Media and Data Communications
DB9-to-DB25 Adapter • Use this to adapt a 9-pin COM connector on the back of a computer to mate with a 25-pin serial DCE devices, such as a modem NETE0510: Communication Media and Data Communications
Null Modem • Use this female-to-female cable in any application where you wish to connect two DTE devices (for example, two computers). A male-to-male equivalent of this cable would be used to connect two DCE devices. NETE0510: Communication Media and Data Communications
HSSI • HSSI is a physical interface at speeds up to 52 Mbps • Become standard interface between DS3 rate of 45 Mbps and the OC-1 SONET interface of 51.84 Mbps for everything from WAN connectivity to a DTE-DCE direct-channel interface NETE0510: Communication Media and Data Communications
HSSI (cont’d) Fiber-optic modem Rack NETE0510: Communication Media and Data Communications
IEEE802 Physical Interfaces • 3 common MAC physical interfaces for the IEEE 802 architecture model are: • Ethernet (802.3) • Token Ring (802.5) • Wireless LAN (802.11) NETE0510: Communication Media and Data Communications
10-Mbps (Legacy) Ethernet • Many different types of Ethernet access: • 1 Base5, 10Base2, 10Base5, 10BaseF • Each type defines both wiring and device terminating the end of the wiring • 10Base5 (Thicknet) and 10Base2 (Thinnet) • 10 refers to 10-Mbps Ethernet • Base stands for baseband • Baseband signaling indicates that Ethernet signals are the only signals carried over the media system • Most common connectivity is via twisted-pair using 10BaseT or 100BaseT standards with no more than 100 m from central bus or switch NETE0510: Communication Media and Data Communications
Comparisons of Ethernet Cabling Specifications NETE0510: Communication Media and Data Communications
Fast Ethernet • 100 Mbps, new preferred standard • FastEthernet specifications include mechanisms for autonegotiation of the media speed. • Vendor can produce dual-speed Ethernet interfaces that can be installed and run at either 10 Mbps or 100 Mbps automatically • Autonegotiation allows the devices to perform automatic configuration to achieve the best possible mode of operation over a link NETE0510: Communication Media and Data Communications
Fast Ethernet (cont’d) • Three media varieties • 100BaseTX: uses 2-pair Category 5 UTP cable • TX segment type is a twisted-pair segment that uses two pairs of wires and is based on data grade twisted-pair physical medium standard developed by ANSI • 100BaseFX: uses fiber-optic cable • FX is based on fiber-optic physical medium standard developed by ANSI and uses two strands of fiber cable • 100BaseT4: early implementation of Fast Ethernet, uses 4-pair Category 3, 4, or 5 UTP cable • T4 segment type is a twisted-pair segment that uses four pairs of telephone-grade twisted-pair wire, half-duplex • 100BaseT2: full-duplex, 100 megabit over two pairs of Category 3 • Too late to make much of an impact NETE0510: Communication Media and Data Communications
Gigabit Ethernet • Idea when budget is tight but require higher bandwidth • Employ all the same specifications defined by the original Ethernet standard, including the same Ethernet frame format and size • 1000BaseT physical layer provides 1-Gbps Ethernet signal transmission over four pairs of Cat-5 UTP cable • Use five-level (PAM (Pulse Amplitude Modulation)-5) encoding (5 voltage level: +2, +1, 0, -1, -2 V) along with four wire pairs, able to provide 250 Mbps per pair • PAM-5 is used to reduce inter-symbol interference between the unshielded pairs. • Can transmit signal for 100 m over twister-pair cable and longer with fiber-optic cable NETE0510: Communication Media and Data Communications
Step-index Profile The proportion between diameters of core and cladding e.g. 62.5/125 (µm) NETE0510: Communication Media and Data Communications
Gigabit Ethernet (cont’d) • 1000BaseT: use 4-pair CAT-5 balanced copper cabling and a 5-level coding scheme • 1000BaseCX: use 150-ohm shielded copper cable and supports a max length of 25 m • 1000BaseF: use fiber-optic • 1000BaseFX: use 62.5/125 multimode fiber and supports a max distance of 412 m • 1000BaseSX: use 50/125 or 62.5/125 multimode fiber with max distance of 550 m • 1000BaseLX: use 9/125 single-mode, 50/125 multimode, or 62.5/125 multimode fiber with max distance of 5 kms • 1000BaseZX: use 9/125 single-mode fiber with max distance of 100 kms • 10-Gbps Ethernet: only fiber-optic cable NETE0510: Communication Media and Data Communications
Token Bus and Token Ring • Physical interface for IEEE802.4 Token Bus and IEEE802.5 Token Ring is the DB connector, interfacing with IBM Type 1 shielded twisted-pair cable. • Token ring: Physical star, logical ring • Uses special 3-byte frame called a token travelling around the ring. • Coaxial cable connections are also available (for Token Bus) • Token ring LAN speeds of 4, 16, 100 Mbps and 1 Gbps have been standardized by the IEEE 802.5 working group. • Token Ring is usually run in Type 1 (2-pair STP), Type 2 (4-pair STP), Type 3 (UTP), and Type 5 (fiber-optic cable) MDI port: medium dependent interface used to connect to other hub or switch without crossover cable required Media access unit (provide logical ring) NETE0510: Communication Media and Data Communications
Physical Media Comparison NETE0510: Communication Media and Data Communications
Wireless LAN (IEEE802.11) • IEEE802.11 specifies connectivity between LAN devices using radio-based equipment • 802.11 is similar to 802.3 for wired LANs but use CSMA/CA instead of CSMA/CD • Collision detection cannot be used for radio frequency transmission because when a node transmits over the air, it cannot hear other nodes on the network • Support two types of operating configurations: • Adhoc or independent do not need an access point • Infrastructure need an access point • Access point acts as a bridge in a wired LAN NETE0510: Communication Media and Data Communications
Wireless LAN (cont’d) NETE0510: Communication Media and Data Communications
Wireless LAN (cont’d) NETE0510: Communication Media and Data Communications
Outline • Physical Layer Protocols and Interfaces • Accessing the Network • Consumer • Corporate or Business • Copper Access Technologies • Cable Access Technologies • Fiber Access Technologies • Air Access Technologies NETE0510: Communication Media and Data Communications
Consumer or Residential Alternatives • Existing copper phone line: • Plain old telephone service (POTS) • Dialup • ISDN • Basic rate interface (BRI) • DSL • Cable line • Cable modem • Wireless • Direct broadcast satellite (DBS) • Very small aperture satellite (VSAT) NETE0510: Communication Media and Data Communications
Consumer or Residential Alternatives NETE0510: Communication Media and Data Communications
Last-Mile Link • The link that spans the last mile from the home to a network service provider • Such services typically connect a home to an existing network CATV = Cable Television POTS = Plain Old Telephone Service NETE0510: Communication Media and Data Communications
Corporate or Business Access Alternatives • Copper • All consumer methods • DS1, FT3, DS3 • ISDN • Fiber • DS3 • SONET OC-N NETE0510: Communication Media and Data Communications
Corporate or Business Access Alternatives NETE0510: Communication Media and Data Communications
Outline • Physical Layer Protocols and Interfaces • Accessing the Network • Copper Access Technologies • Cable Access Technologies • Fiber Access Technologies • Air Access Technologies NETE0510: Communication Media and Data Communications
UTP • A transmission repeater system over a four-wire twisted-pair is defined and called a t-carrier system e.g. T1 system • Signal and service is referred as a DS1 • T1 circuits are brought to the customer location via either copper or fiber • UTP is very popular type of copper wiring NETE0510: Communication Media and Data Communications
UTP Ratings (EIA/TIA Standards) • Category 1 • used for voice and low-speed data transmission up to 56 kbps • Category 2 • Ideal for 4-Mbps token ring, RS-232, RS-422, and AS/400 • Category 3 • Ideal for telephone, 4-Mbps token ring, and 10BaseT applications • Category 4 • Used for 16-Mbps token ring • Category 5 • Suitable for 100BaseT Ethernet, 10-Mbps token ring, and OC-3 ATM • Category 5e • Support speed up to 1.2 Gbps and typically used for Gigabit Ethernet • Category 6 • Newly designed for Gigabit Ethernet and future apps NETE0510: Communication Media and Data Communications
Dialup or Legacy Analog Modem • Current standard for 56-Kbps modem is V.92 • Prior to 56-Kbps modems, the best speed between two modems was 33.6 Kbps. • With V.90, connection speeds can exceed 50 Kbps • Up to 54 Kbps download, 33.6 Kbps upload • V.92 provides 56 Kbps with enhancements: • Upload speed increased to 48 Kbps: • improve video conferencing and file uploading • Startup time reduced from about 20 seconds to about 10 seconds • Internet call waiting • Receive a call while the modem is still connected NETE0510: Communication Media and Data Communications
Dialup or Legacy Analog Modem NETE0510: Communication Media and Data Communications
ISDN • ISDN provides one of the best disaster discovery alternatives for services such as Fame Relay and IP (VPNs and Internet access) • Built on the TDM hierarchy developed for digital telephony • ITU-T defines two standards for physical interface to ISDN • BRI (Basic Rate Interface) • PRI (Primary Rate Interface) • The physical layer provides transmission capability, activation, and deactivation of terminal equipment (TE) and network termination (NT) data (D)-channel access for TE, maintenance functions, and channel status indications NETE0510: Communication Media and Data Communications
ISDN (cont’d) NETE0510: Communication Media and Data Communications
ISDN Devices NETE0510: Communication Media and Data Communications
ISDN Devices NT1 or NT2 Terminal Adapter ISDN PCI card ISDN router (TE1) NETE0510: Communication Media and Data Communications
ISDN Reference Points • R — References the connection between a non-ISDN compatible device TE2 and a TA, for example an RS-232- serial interface. • TE2 - TA • S — References the points that connect into the customer switching device NT2and enables calls between the various types of customer premises equipment. • NT2 – TE1, NT2 - TA • T — Electrically identical to the S interface, it references the outbound connection from the NT1 to the ISDN network or NT2. • NT1 – NT2 • U — References the connection between the NT1 and the ISDN network owned by the telephone company. • NT1 – Telephone company NETE0510: Communication Media and Data Communications
ISDN Access Options TE1 TE1 ISDN router TE2 TE1 ISDN router NETE0510: Communication Media and Data Communications
BRI and PRI • BRI • Provides two 64-kbps bearer (B)-channels for the carriage of user data and one 16-kpbs control and network management D-channel • 2B+D = (2x64 + 16) = 144 kbps • Suitable for voice, data, and video (low rate) • PRI • 23 64-kbps bearer (B) channels and one 64-kbps signaling channel (North America) 23B+D (DS1 equivalent) • 30B+D for international (E1 equivalent) • Higher bandwidth or shared customer devices NETE0510: Communication Media and Data Communications
ISDN: BRI NETE0510: Communication Media and Data Communications
ISDN PRI (cont’d) • ISDN PRI provides a single 1.544 Mbps DS1 or a 2.048-Mbps E1 data rate channel over a full-duplex synchronous point-to-point channel using TDM hierarchy • DS1 data stream comprises 24 DS0 channels of 64 kbps each containing 23 B-channels at 64 kbps each and one D-channel at 64 kbps NETE0510: Communication Media and Data Communications