Intrastate Vs Interstate

Consequently, intrastate telephone tariffs are generally higher than interstate telephone tariffs. For example, a telecommunications networking manager at Chemical Bank in New York City remarked to me that it cost more to run a T-1 channel from lower Manhattan to mid-town Manhattan than it cost to run the same T-1 line from New York City to Chicago. Intrastate and intercity rates were higher than FCC-mandated interstate rates. Similarly, telephone channels run from northern California to...

Dense Wavelength Division Multiplexing

Fibers can operate using multiple wavelengths of light. This is a form of frequency division multiplexing (FDM), with each wavelength being a different color of light. At first, only two colors were used, but this has increased to 16 colors, 32 colors, and up to 256 colors (wavelengths) of light. This is used on telephone network fiber. It is called Dense Wavelength Division Multiplexing (DWDM). DWDM is a fiber optic transmission technology that multiplexes (combines) different digital...

B A

Several RF frequencies are used to communicate with cell towers. Frequencies carry multiplexed packets from any phone at any time. Phones frequently hop to send packets. Each packet has an identifier code. Figure 8-14 Cell phone transmission technologies. lular systems using extremely low power (micro-cell and pico-cell networks). Finally, the TIA EIA IS-91 Analog Cellular standard is the TIA analog cellular standard version incorporating IS-3, IS-88 narrowband analog, and IS-94 and...

Local Area Networks

How many active peer-to-peer connections can Windows 95 98 and NT support A. Token ring, ArcNet, Ethernet D. None of the above Answer C. 3. What is the most widely used NIC D. None of the above Answer A. 4. What wiring can Ethernet use E. None of the above Answer D. 5. What is the most popular LAN wiring 6. What features make servers robust and reliable A. Hot-swappable power supplies C. Error detecting and correcting RAM Answer B, C, and D, because hot-swap power supply makes them easy to...

Digital Subscriber Line Offerings

These offerings vary in up-line and downline speed. We discuss these different types of DSLs including ADSL, RADSL, SDSL, HDSL, and VDSL. They are different technologies and services aimed at providing high-speed digital transmission over conventional telephone wiring (using existing telephone company wiring plant) to consumer premises. Asymmetric Digital Subscriber Lines ADSL transmits an asymmetric data stream, with higher speed downstream to the subscriber...

Telecommunications Evolution and Future

What ways will not provide high-speed access to the Internet to the home F. Power lines Answer A,C,D,E, and F. D. Data Subscriber Line Answer C. 3. What units of measure are used to represent transmission speeds to the home 4. Cable modems operate at what speeds 5. Analog modems operate at what speeds 6. What technologies are converging A. Voice, WAN, LAN, video, image, and wireless with microelectronic technologies B. Voice, WAN, LAN, video, and wireless with microelectronic technologies C....

Info

A, M - yM ifA A A - This chapter continues examining voice communications. Because politics and telephony are inseparable companions, regulation for both local and long-distance telephony communications is also examined along with the current competitive environment for telephone services. Finally, the chapter examines telephone switches and PBXs contrasting them with CENTREX service. AT& T originally designed the North American Numbering Plan (NANP) back in 1947. It conforms to the ITU...

A

Access, voice networks, 55 Active hubs, 334 ADCR, See Alternate Destination Call Redirection (ADCR) Add Drop Multiplexers (ADM), 418, 451-52 Address Resolution Protocol (ARP), 560, 562-63 ADSL Lite, 612-13 Advanced Intelligent Network (AIN), 168-69 Advanced Mobile Phone System (AMPS), 479, 521-22 Advanced Networks and Services (ANS), 541 AIN, See Advanced Intelligent Network (AIN) Airtouch Cellular, 529 Alternate Destination Call Redirection (ADCR), 135 Alternate Mark Inversion (AMI), 415-16...

Satellite Voice Services

There are several new telecommunications services on the horizon aimed at voice communications such as the Ellipso and GlobalStar. An early LEO voice communications satellite system was Iridium. Iridium came on-line November 1998. Unfortunately the business plan was not well thought out and Iridium failed. It is included in the chart here for comparison purposes only. Iridium was a planet-wide cellular communications system. The Iridium hand-held cell phones utilized either terrestrial cellular...

Service Profile Identifier Number

National ISDN-2 (NI-2) uses SPIDs (Service Profile Identifiers). SPIDs are free-formatted numeric strings between 3 to 20 characters in length. The Local Exchange Carrier, or LEC (ISDN service provider), assigns SPIDs when the customer places an order for a BRI. The customer typically enters the SPID into the terminal before the terminal can initialize at Layer 3. SPIDs are used only inside North America. The SPID number assigned to a fully initialized ISDN terminal enables the Stored Program...

Satellite RF Bands

Satellites use different microwave frequency bands to carry communications. These frequency bands have different operating characteristics. Many satellites use C-band, because C-band transmissions have a broad footprint that makes them especially useful for signals that must be broadcast over a wide area. C-band signals are relatively weak and often require large and somewhat expensive earth station antennas, but they are relatively immune to atmospheric interference. The earth's atmosphere is...

LAN Market Summary

LAN products fit into three different network areas Backbone LANs. Voice, Video, and data LANs. Backbone LANs interconnect the work area LANs in a facility to services and servers used by everyone in the enterprise. Work area LANs support small workgroup operations. They provide local disk and printer sharing for an individual organizational unit. Work area LANs may be more PC-based. Backbone LANs have robust servers specially designed and configured to deliver specific services to work area PC...

Radio Frequency Communications

Dramatic changes in the way RF communications is used have taken place over the last several years. However, RF communications is equivalent to any other communications channel or pipe, like fiber optic cable or copper wire. The physics of RF communications remains the same as always, but the electronics implementing it have been combined with data communications technologies to radically enhance and alter RF applications. Today RF communications provides anywhere cellular phones, paging,...

The Inter Exchange Carriers

Inter-Exchange Carriers (IXCs IECs) are telephone companies that transport calls between telephone exchanges. They carry long-distance and toll charge calls. AT& T, MCI WorldCom, Qwest, Cable and Wireless, and others are IXCs IECs. Since the breakup of AT& T in 1984, IXCs IECs interface with local telephone companies at POPs. The POPs serve offices set up in each LEC. The POP is the point to which the local telephone company connects its customers for long-distance dial-up and leased-line...

Baud Vs Bits Per Second Vs Bytes Per Second

A bit is a voltage state that either is present (on, yes, mark, 1, +5 volts, or positive) or absent (off, no, space, 0, 0 volts, or negative). It is the smallest unit of data recognized by computers. All data (letters, numerals, symbols) handled by computers is digitized, i.e., expressed entirely as a combination of 0's and 1's. A bit is the smallest unit of information (0 or 1) in a binary system of notation. As we have seen, bits are used in combination to form...

And Satellite Channel Service Suppliers

There are several satellite earth station and NOC center vendors. U.S. companies have dominated the VSAT market. Some U. S. vendors are Orbital Sciences Inc., Hughes, AT& T, GTE, and Scientific Atlanta (now ViaSat). Hughes Network Systems owns and operates the most private satellites (C-band and Ku-band). It offers a comprehensive range of satellite telecommunications products, including the Integrated Satellite Business Network (ISBN), Telephony Earth Station (TES), and a TDMA network of...

Multiplexing Hierarchy T1 T1c T2 And T3

The T-carrier system is the North American telephone industry standard for interconnecting digital communication systems. T-1 circuits are defined as any digital communication system operating at a synchronous data rate of 1.544 Mbps. Data can be transmitted over a T-1 circuit at 56 Kbps to 1.544 Mbps. Voice channels use 64 Kbps. Twenty-four simultaneous digitized voice signals are time division multiplexed on one T-1 circuit. T-1 circuits transport data or voice using a framing format called...

Cable Modem Network Components

Cable modems provide low-speed (typically 200 to 400 Kbps) uplinks to the Internet and high-speed (typically 800 to 1,200 Kbps) downlinks from the Internet. The cable modem's up- and downlinks are on shared channels. This means that performance can vary depending upon loading from other subscribers. In our experience with COMCAST cable modems, this has not been the case. In Figure 9-16, the Internet user, Pete, sits at his office PC and connects through his local Ethernet to a cable modem. Not...

Frame Relay Access Device

A Frame Relay Access Device or Frame Relay Assembler Disassembler (FRAD) is a telecommunications network component that formats outgoing data for transmission across a frame relay network. It strips the data back out at the other end, presenting it to the target system as if it were the original data stream. A FRAD is the frame relay network counterpart to an X.25 PAD (see Figure 7-14). Similar to HDLC-based packet networks, frame relay networks pass data using OSI Layer 1, Layer 2, and Layer 3...

Centrex Central Office Exchange

CENTREX (Central Exchange) is a generic name for telecommunications services, similar to those provided by CPE PBXs, offered through CO switches. While a PBX is located at a customer's site, a CENTREX system is located at a local telephone company's CO (see Figure 4-19). The CENTREX customer leases a dedicated partition of the CO exchange, which is part of the public telephone network. Special switching functions, user features, as well as access to the public telephone network are provided...

Telephony Services

Common carriers are organizations providing regulated telephone, telegraph, telex, and data communications services. For the last few decades, the telephone network was optimized to carry voice telephone calls. Digital voice Class 1 Class 2 Class 3 Class 4 Regional Sectional Primary Toll Center Regional Sectional Primary Toll Center Competitive Local Exchange Carrier (CLEC) Class 5 Local Exchange Carrier (CLEC) Class 5 Local Exchange Carrier (CLEC) Class 5 Figure 4-7 CLEC network switching...

Digital Phones

The rapidly increasing number of pocket and transportable cellular telephones requires network equipment that handles the low-power phones and more simultaneously active subscribers. Digital cell phones are needed to Figure 8-15 Nextel iDEN i1000 TDMA 800MHz cell phone. more effectively share frequencies. These digital cell phones employ two technologies to meet these needs, Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA). Time Division Multiple Access The Cellular...

Chapter Review Questions

How many active peer-to-peer connections can Windows 95 98 ME and NT 2000 support A. Token ring, ArcNet, Ethernet 3. What is the most widely used NIC 4. What wiring can Ethernet use 5. What is the most popular LAN wiring 6. What features make servers robust and reliable A. Hot-swappable power supplies C. Error detecting and correcting RAM 7. What is the IEEE designation for Ethernet 8. The Universal Naming Convention (UNC) designates servers how 10. What internetworking components work in OSI...

Ds3

T-carrier circuits were defined and implemented for speeds faster than DS-3. However, any circuit with bandwidth greater (higher transmission speed) than a DS-3 circuit is sold today as most typically a SONET ring OC (Optical Carrier) circuit. This hierarchy was set up just to bug Pete. Why didn't the telephone companies make two T-1 channels a DS-2 channel rather than a DS-1C channel And why for a DS-1C channel is the speed not 2 times 1.544, or 3.088 Mbps Of course the telephone companies...

Cat5

While CAT-3 and CAT-5 cables may look identical, CAT-3 is tested at lower transmission speeds. If CAT-3 wire is run at higher speeds, it can cause network transmission errors. CAT-3 cabling is NEXT certified for only 16-MHz signals, while CAT-5 cable must pass a 100-MHz signal test permitting it to carry data at 100-Mbps speeds. Figure 6-37 shows two round CAT-5 cables. There are more differences between CAT-5 and CAT-3 cable beyond CAT-5 twisted pair cable having more twists per foot than...

Cable Television Network Evolution

A single television channel broadcast across coaxial cable requires a bandwidth of 6MHz. This means that 6MHz of frequencies in the total range of frequencies broadcast across a coaxial cable are needed for every TV channel the coaxial cable carries. Because it makes calculations easy in this book, we are going to use 10MHz as the bandwidth required for a single TV channel. Original CATV systems supported the 12 broadcast channels with pushbutton tuners (see Figure 9-14). These tuners used a...

Data Codes

For example, Morse code gives dots and dashes meaning by turning them into letters and numbers. Fundamentally, computers just deal with voltage levels. We do not need to understand voltage level details, but we do need to understand that different voltage levels can represent 0's and 1's. Still, most humans do not read 0's and 1's (binary information), so we need to convert them into another form such as the following ASCII code. The voltages represent...

Internet Service Providers

ISPs typically offer access to the Internet for a fee. Some ISPs provide free Internet access in exchange for viewing advertising or for gathering information on Internet use. ISPs can be large or small. They may be a regional network provider, reselling high-speed Internet access to smaller ISPs. The smaller ISPs in turn sell Internet access to individual Internet users. The Moulton Company, for example, purchases Internet access from MDconnect.com, PSINet, and MCI. All offer direct unfiltered...

Digital Subscriber Line

DSL (Digital Subscriber Line) technology brings high-speed Internet access to residences and small businesses using existing copper wire telephone lines. xDSL represents all variations of DSL, such as ADSL, HDSL, and RADSL. When a home or small business is within 18,000 feet of a telephone company CO offering DSL service, it may be able to receive data at speeds up to 6.1 Mbps. This can support transmission of motion video, audio, and simulated 3-D images using Virtual Reality Modeling Language...

Wireless Local Loop

Wireless Local Loop (WLL) connects telephone subscribers to the Public Switched Telephone Network (PSTN) using RF transmission as a substitute for copper wire local loops between subscriber premises and the CO telephone switch. WLL includes cordless access, proprietary fixed radio access, and fixed cellular technologies. Global WLL products are projected to service millions of subscribers in the 21st century. Many of these subscribers live in emerging economies like China, India, Brazil,...

Cable Modem Operating Frequencies

What makes cable modem operation possible and two-way communications possible on the new 1GHz cable plant is that the cable modems use OSI 802.2 and TCP IP protocols to carry data from many subscribers back to the CATV head-end facility that contains a Cable Modem Termination System (CMTS). The CMTS talks to all attached cable modems, but cable modems can only talk to the CMTS. When two cable modems need to talk to each other, the CMTS relays messages between them. The cable modem takes the...

Max

Figure 5-23 Protocol framing formats. although few products implementing fourth-generation protocols exploited this capability. A variation of the High-level Data Link Control (HDLC) protocol carries the signaling information in SS-7. IBM's Synchronous Data Link Control (SDLC) protocol is a fourth-generation protocol. Fourth-generation protocols send text or binary data in frames, perform better CRC error detection (because they use an improved CRC), and correct frames having errors by...

Ieee Lan Standards

IEEE standards influence the development of new LAN hardware, cabling, and software products. IEEE LAN standards fall under the IEEE 802 committee. The original LAN standards were all under IEEE 802.3, IEEE 802.4, and IEEE 802.5 designations. IEEE 802 standards have a much broader scope of coverage today. The early IEEE LAN standards for LANs are identified in Figure 6-30. When you see IEEE 802, just think LAN products. Of the original standards, the 802.3 is the most active today, with...

Ethernet Vs Token Ring

How do the token ring and Ethernet's CSMA CD protocols compare Is one better than the other In reality, one is not better than the other, they are just different. Ethernet came out in 1984, while the token ring arrived in 1987. (1987 was a banner year for IBM because the token ring, the PS-2, and OS 2 all were released that year.) Which is more sophisticated I think the token ring. Does that make the token ring better No, not that I can see. The token ring's greater sophistication is needed...

Common Channel Vs Inband Signaling

There are two different ways to perform signaling. Our analog telephones provide in-band signaling, while ISDN phones use common channel signaling. In-band signaling was the first type of signaling deployed in the telephone network. In-band signaling is defined as voice and signaling information sharing the same communications path. Think of this When you are talking on your analog home phone and your fingers hit keys on the telephone's numeric keypad, what do you hear You hear the DTMF beeps...

Carrier Identification Codes

Carrier Identification Codes (CICs) are numeric codes that, as originally devised, enabled LECs, as providers of inter-Exchange (IXC) access services, to identify access customers in order to bill and route traffic to such customers. The NANP administrator assigns these codes using guidelines developed by the Industry Carriers Compatibility Forum (ICCF), under the auspices of the Carrier Liaison Committee (CLC) that is sponsored by the Alliance for Telecommunications Solutions (ATIS), an...

Metered

Dial-up contention services are charged for metered use. That means that the LEC runs a stop-watch on our long-distance calling and reports the number of minutes (seconds) we called long distance for each hour (or minute) during the day. Then our long-distance carrier computes our longdistance charges by applying this usage pattern to our negotiated long-distance rates. How metered charges are calculated can impact a telephone bill significantly. Metered charges can be calculated by the full...

LineOfSight Microwave Transmission

The RF and satellite communications that promise to make high-speed digital planet-wide networks a reality are based upon Line-Of-Sight (LOS) microwave technology. Most RF communications uses RFs classified as microwave frequencies. Microwave frequencies provide a significant advantage for voice, video, and data communications. A single microwave radio channel can carry 6,000 voice channels in a 30-MHz bandwidth. This capac- Microwave Tower Microwave Tower Microwave Tower Microwave Tower ity is...

Trunk Cards

A wide range of digital communications trunks is available from local telephone companies. These high-speed trunks provide high-quality voice and data transfer to and from local telephone company CO switches. PBXs use different trunk cards to connect to these high-speed communications trunks. The physical trunk adapter may be the same for different trunk interfaces. The only difference between one card and another is the PBX software controlling the card. T-1 Trunk Cards T-1 trunks are the...

Serial vs Parallel

Serial Bits Parallel Bits Transmissib

Serial vs. parallel transmission simply describes how bits travel from one component to another component across a network. In a computer, parallel transmission is used because distances are short and data must be manipulated quickly. Once outside the PC, serial transmission dominates. Serial transmission is single-file, Indian-style transmission, where one bit follows another down a single pathway as shown in Figure 5-2. Serial transmission requires one, two, or four wires, depending upon the...

Ccitt V42

Uses synchronous transmission to increase effective data rate to as much as 120 of the rated modem speed. Error detection and correction Data compression up to 2 1 Similar to V.42 bis with less effective data compression. Transmission speed can increase as much as 200 over modem speed. This protocol includes adaptive packet sizing and data optimization, producing improved data transfer speeds. Maximum improvement on clear telephone lines is 120 . Uses full duplex...

Switched Multimegabit Data Service

Switched Multimegabit Data Service

Switched Multi-megabit Data Service SMDS is a packet-switching service that provides LAN-like performance and features over a metropolitan area. SMDS transports data over wide areas at speeds up to T-3 speeds of 44.735 Mbps. SMDS services include group addressing, connectionless transport, and fixed packet delays. SMDS is based upon the IEEE 802.6 MAN Standard. SMDS uses cell relay switching technology at Layer 2, the data link layer, similar to ATM networks. Cell relay breaks Layer 3, the...

B8ZS Bipolar Eight Bit Zero Substitution

Tion and supports clear channel signaling. On B8ZS channels, all T-1 bandwidth can be used for data transmission supporting clear channel, or full 64-Kbps DS-0 channels. To use this clear channel signaling, a Channel Service Unit CSU conforming to B8ZS signaling must be placed at each end of the T-1 link. A B8ZS transmitter in the CSU watches the data stream for excessively long strings of 0's. When detected, the long strings of 0's are replaced by a bipolar encoding violation before being...

Broadband Isdn Services

Broadband ISDN B-ISDN is designed to provide transmission capacity suitable for high-quality television, video teleconferencing, video telephony, image, and high-bandwidth data communications. B-ISDN channels can provide aggregate bit rates around 155 Mbps and 622 Mbps. B-ISDN is intended for widespread use in five years. Defined B-ISDN service categories are interactive services and distributive services. Conversational services, including video telephony, video teleconferencing, and...

X75 And X121 Standards

The X.75 and X.121 specifications describe the interface between two separate X.25 packet-switched networks. These interfaces are concerned with routing and addressing between X.25 networks see Figure 7-6 . X.75 is a signaling protocol used to connect X.25 packet-switched networks on international circuits. X.75 defines how X.25 packet-switched networks allow international links to be established, even where some incompatibilities exist. X.75 is a gateway interface protocol at network Figure...

Alternate Mark Inversion And Bipolar 8bit Zero Substitution

Ami Alternate Mark Inversion

In 1988, clear channel transmission became an option for T-1 service from AT amp T. Users could now transmit DS-0 or DS-1 signals without restricting the consecutive zeros. T-1 channels are encoded using Alternate Mark Inversion AMI . AMI encodes each 1 bit as a positive then a negative voltage. The receiving device on a T-1 channel detects dropped bits because it receives two positive or two negative voltage signals back to back when it should always receive a positive then a negative then a...

Frequency Division Multiplexing

A frequency division multiplexer combines multiple parallel information streams into a single communications channel. Each of the information streams, or sub-channels, is assigned a separate frequency within the broader frequency range of the single communications channel interconnecting the frequency division multiplexers. In Figure 5-32, Channel 1 operates at high frequency, Channel 2 at medium frequency, and Channel 3 at low frequency. Could Channel 1 carry voice, Channel 2 HDLC data, and...

FDM and TDM Applications Overview

FDM and TDM are used throughout telecommunications systems. For example, cable modems run across a frequency division multiplexed system. DSLs are also frequency division multiplexed on the same pair of telephone wires used to carry a voice communications channel. T-1 channels are time division multiplexed DS-0 channels. PBXs use TDM on their voice bus to make voice circuit connections. Some cell phones use a combination of both FDM and TDM. The point here is that to understand how these...

Ccitt V34

33,600 Bps - up and 56,000 Bps - down The protocol handshaking and data compression performed by modems is invisible to our PC while it is transmitting data. So to every PC, a modem appears as an OSI Layer-1 device when in fact they are really sophisticated devices incorporating OSI Layer-1 and Layer-2 functions with data compression. This results in a key configuration option for the interface between the modem and the PC. For these sophisticated modems to operate properly with a PC, the PC...