TAP YIPL

home *** CD-ROM | disk | FTP | other *** search

/ TAP YIPL / TAP_and_YIPL_Collection_CD.iso / PHREAK / SYSINFO / 9X_DCOM.TXT < prev next >

Wrap

Text File | 2000-02-16 | 30.3 KB | 635 lines

STATION ID - 7047/3.12 9x Datakit Network FOR OFFICIAL USE ONLY This is a 9x system, restricted to authorized persons and for official 9x business only. Anyone using this system, network or data is subject to being monitored at any time for system administration and for identifying unauthorized users or system misuse. Anyone using this system expressly consents to such monitoring and is advised that any evidence of criminal activity revealed through such monitoring may be provided to law enforcement for prosecution. 1 0 1 1 0 0 1 0 1 0 1 101 1 1 001 1 0 0 1 1 0 1 0 1 1 0 11 001 0100 10 010 12 010 1 1 01001 11 1 1 00 11 1 110 0 0 0 1100 1 0 1010 00011 11 1010011 11010 0 11110101010 0101 011 0001100 11100 0001 110 000011 00001101 10100010101001010101000101010100101010101001010101110010010100100010100101010 10100101010100010101000100101001001011001010001001001010101010100100100101010 101000101010100101010101010 US Switching Hierarchies 110101001101010010101000 10101010101010101010101010101101100011010101010101010101010011100101010101010 101010101000111010001010010101 DiGiTaL Telcomms 01010001010100010101010100101 10101001010100100101010101010101010100010101010100100101010101010101010100101 10101001010101010100101010101010 By Hybrid 01010101010110101010100101010001 written for 9x sometime in 1998 Index: ~~~~~~ 1. Intro 2. Switching Hierarchy 3. North American Digital Hierarchies 4. The Local Subscriber Loop 1. Intro: ~~~~~~~~~ thanx for reading my 4th file for 9x, Bascially its just a few things I think have never covered before. I have to say at this point that you may want to get a cup of coffee (or somthing else) to keep you awake, as some of the subjects covered in this t-file may be less appealing to some people. If you don't want to know about any of the things listed above in the index, then hang up now. OK, lets get started. Most of my 9x files have been UK specific, this file is for you US dudes, hopefully you can make some use of it. All of the information in this article comes from various sources, such as telco books, and technical manuals. I have taken the time to write all of this, so I hope you can find the time to read it all! Please excuse my crude looking diagrams, I hope you can all make sence of them, I have designed this article so it is easy to read... So of the other files I have read on Switching Systems etc, just look like massive essays, and you end up skipping through the whole thing. I have tried to make this as interesting as possible... Enjoy. 2. Switching Hierarchy ~~~~~~~~~~~~~~~~~~~~~~ Ok, let's start with the basics. Before anyone can understand the US switch system, they need to understand how it has evolved to be what it is today. Early phone customers where linked by point-to-point lines as shown in the following shit looking diagram: (1) / \ / \ / \ / \ Point-to-Point Connections / \ / \ / \ / \ / \ / \ / \ / \ (2)------------------------------------------------(3) This kind of connection seems like a simple system (it is), However, as the number of customers increaseases, the number of lines incrteases even faster. There are over 165 million phone customers in the US and Canada, it would be imposible to connect everyones phones with this simple form of point-to-point connection. The first phone eXchanges were manual and all of the calls were handled by operators (probably as dumb as the 555-1212 operators). This is not posible today as there are so many phone subscribers, and most of the world uses automatic switching sytems, either employing electromechanical realys or the latest computer controled electronic machines, (I'll discues this later). A central switching point allows the connection of customers in a single 'star' fashion, as shown in the following diagram, pheer my ascii: (1) (6) | (2) \ | / \ | / \/~~~~~~~~~~~\/ | Central | Central Switching | Switch | Point /\___________/\ / | \ / | \ (5) | (3) (4) In this diagram ALL calls are switched through the central switching point, dramatically reducing the number of lines required in the previous diagram. As phone usage grew, network switching evolved into a hierarchy that consisted of the 5 levels shown in the next diagram: Class 1 Class 2 Class 3 Class 4 Class 5 /~~~~~~\ _____ _____ _____ | |________| |_________| |_________| |_________/~~\ | | a | | | | | | \__/ \______/ ~~\~~ ~~~~~ ~~|~~ | \ | | \ | | \ b | b | \ | | \ | /~~~~~~\ a _____ \ _____ __|__ | |________| |_________| |_________| |_________/~~\ | | | | | | | | \__/ \______/ ~~~~~ ~~~~~ ~~~~~ Regional Sectional Primary Toll End Center Center Center Center Office a: Final Trunks b: High-Usage Trunks Upon divestiture of the RBOC's from AT&T, the access by long distance companies to local networks changed, and for practical purposes eliminated the traditional switching hierarchy in the US. Just before divestiture at the lowest level there where some 20,000 Class (5) Switching centers called End- Offices, which interface directly with the customer equipment via the LOCAL LOOP. At the next level there where 1,300 or more Toll-centers (Class 4), they where called this because their usage implies higher rates. Then came 265 Primary Centers (Class 3) and 75 Sectional Centers (Class 2). At the top of the hierarchy where Regional Centers (Class 1), which numbered only 12 (10 in the US and 2 in Canada). Traffic is always routed through the lowest available level in the hierarchy; if that level is BUSY, higher levels are selected. It was not necessary that Class 4 or 3 offices always home on the next higher ranking office. Possible homing arrangemnts for each class of switching office are shown in the following table: ___________________________________________________________________________ | | Rank | Class of office | May home on ~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ End office | 5 | class 4, 3, 2, or 1 ~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Toll center | 4 | class 3, 2, or 1 ~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Primary center | 3 | class 2 or 1 ~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sectional center | 2 | class 1 ~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Regional center | 1 | All regional centers | | interconnected ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In the US, the divestiture has created the ACCESS TANDEM. This is the gateway between the intereXchange carrier's (For example AT&T, Sprint and MCI) point of presence (POP) and the exchange carrier's end office. End offices and tandems may be served directly from any interexchange carrier location. Routing rules between switching centers determine the selection of fixed set of alternate routes using final or high-usage trunks. There are some limitations to the efficency gains achivable with hierarchical alternate routing. A number of dynamic routing concepts are being used in the North American Toll-Network. Dynamic nonhierarchical routing (DNHR) is AT&T's version of circuit-switched dynamic routing. DNHR is a centralized time- dependant routing scheme that is supposed to increrase network efficiency by taking adavantage of the noncoincidence of busy hours in the North American Toll-Network. Common Channel Interoffice Signaling (CCIS) is used for signaling between phone exchanges in the call path. CCIS is a system for eXchanging signaling information between eXchanges via a network of signaling links instead of the individual voice circuits. Another routing scheme called dynamically controled routing (DCR) is a centralized adaptive routing system developed by Northern Telecom. The DCR concept makes efficient use of the network resources. Basically phones are connected to each other via a hieratchy of switching centers. The lowest level switching center is called the end office. Customers can access other customers connected to other end offices toll free within the local eXchange area. All long distance calls are routed through the interExchange carrier switching offices. The hierarchical system which consisted of the toll center, sectioned center and finally the regional center hage been largely replaced by less compartmentalized system in which dynamic routing concepts are applied on a network basis. The continuing intoduction of new technology in the North American toll network will see a wider application of dynamic routing concepts in the near future. 3. North American Digital Hierarchies. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The design of the North American Digital Network has evolved around a series of hierarchical levels based on the DS-1 (1.544 Mb/s) Primary rate. The DS-1 rate was established by the bell Labs as the transmission rate for the first commercial pulse code modulation (PCM) cable carrier system back in 1962. This rate was chosen as an optimum rate for transmission over existing 6,000 foot spans of 22-gauge eXchange grade cable. At has since been accepted as the basic building block for the North American digital hierarchy. The magority of transmission systems and multiplexers in use in North America today are electrically compatable at this rate, although signaling formats may vary. The DS-1C (3.152 Mb/s) rate was derived by combining 2 DS-1 inputs and adding housekeeping pulses for frame allignment and synchronisation. The DS-2 (6.312 Mb/s) rate was derived by combining 4 DS-1 inputs and adding housekeeping pulses for frame allignment and synchronization. The DS-3 (44.736 Mb/s) rate was derived by combining 7 DS-2 inputs and adding pulses for frame allignment and synchronization, as shown in my following crude looking diagram: DS-1 DS-2 DS-3 1.544 Mb/s 6.312 Mb/s 44.736 Mb/s ~~~~~~~~~~ ~~~~~~~~~~ ~~~~~~~~~~~ A Phone! _______ Digital Signal Hierarchy /~/~~~~\~\ | PCM | _______ ~~|::::|~~ 1|Channel| | M-12 | _______ |____|=========| Bank | 1| Multi | | M-23 | =| |========|plexer | 1| Multi | =| | ___| |========|plexer | =| 24* | ___| | ___| |==========|>> =|Channels ___| 96* | ___| | 24| | 4|Channels ___| 672* | ~~~~~~~ |_______| ___|Channels 7|_______| * Assumes 64 Kb/s Encoding Rate The next step up in the digital hierarchy is the DS-4 (274.176 Mb/s) rate, which has always been the highest level in the North American telecommunications hierarchy. However, all of the new lightawve systems (which I will explain later in this file) go beyond this rate due to the rapid development in this new technology. There transmission rates are all multiples of DS-3 streams. The current rates are 565 Mb/s (12 DS-3s), 1.2 gigabits per second (Gb/s) (24DS-3s), and 2.4 Gb/s (48 Ds-3s). Lightwave systems associated with the SONET use different rates, which will be discused later. All of these digital bit streams use the same TDM techniques. For instance, the DS-3 bit stream is made up in an M-23 Multiplexer by taking 1 but at a time from each of the 7 DS-2 inputs and then interleaving them to form a single bit stream. Housekeeping bits are added at difinate intervals carrying control information. The DS-3 signal, along with 5 other DS-3 signals, can then be connected to an M-34 multiplexer, where the proccess is reapeated again to to create a DS-4 signal. The only digital cable carrier that used thid bit rate (274.176 Mb/s) was the T4M system, which operated over coaxial cable and provided 4,032 voice circuits. Various multiplexing schemes can be used to achieve conversaiton between the levels of hierarchy. The following dialgram shows commonly accepted relationships as well as the names of the digital signal cross-connects used at each level: DiGiTaL Sigmal Building blocks: Digital Bit Rate Cross- signal No. of Connect Level Voicegrade Jumper ~~~~~~~ Channels Type ~~~~~~~~~~ ~~~~~~~ 274.176 Mb/s 4,032 Channels DS-4 ==================================================================== | | |~~~~~~| 44.736 | M34 | Mb/s | MUX | 672 DSX-3 |______| Channels Coax | DS-3 ==================================================================== | | | | |~~~~~~| |~~~~~~| 6.312 | M23 | | M13 | Mb/s | MUX | | MUX | 96 DSX-2 |______| |______| Channels STP | | DS-2 ===========================|======================================== | | | | |~~~~~~| | | M12 | | | MUX | | 3.152 |______| | Mb/s DSX-1C | | 48 UTP | | Channels DS-1C ==========|===============|======================================== | | | | | | |~~~~~~~~~~| | | | | Channel | | |~~~~~~| | | Bank | | | M1C | | |__________| | 1.544 | MUX | | | | Mb/s DSX-1 |______| | | | 24 UTP | | | | Channels | | | | DS-1 ==================|================================================= | | | | |~~~~~~| | |Channel | 64 kb/s DSX-0 |Bank | | 1 UTP |______| | Channel (or DCS) | | | | DS-0 ==================================================================== | | M- Nultiplexer |~~~~~~| STP- Shielded Twisted Pair |Codec | UTP- Unshielded Twisted Pair |______| | | Analog ======================================== 3.1 kHz Voicegrade Channel 1 of the 1st applications of digital signal processing (DSP) in the phone network was the installation of pulse code modulation (PSM_ carrier systems back in the 1960s. This was the introduction of PCM carrier systems and the acceptance of 64 kb/s as the standard for coding voice in the emerging digital network. While 64 kb/s PCM provides good transmission quality, it has been realised for some time that that it is realatively inifficiant in it's use of transmission facility bandwith. Essentially, there are 2 basic techniques which would be applied to increase the circuit capacity: digital signal interpolation (DSI) and low-bit-rate encoding (LBRE). DSI is a proccess which time-shares a fixed number of digital voice channels between a larger number of talkers. Since the average speech activty in a 2- way voice converstation is typically on the order of 30% to 40% in each direction, it is possible to fill in speech gaps in 1 converstaion with talk spurts from another conversation. Practical systems which provide a 2:1 concentration ratio (a doubleing of transmission capacity) are caommercialy available. Higher concentration ratios are realizable when the network carries a high proportion of voice traffic. Lower concentration ratios are neccesary with data traffic because data signals normally operate continuously on a given call. LBRE is a technique which uses advanced signal-proccessing techniques to reduce the number of bits required to encode the voice signal. The most 'prommising' technique is to exploit the correlation between succesive speech samples. The difference between the actual voice sample and an estimated (or predicted) value based on the immediate precceding voice samples is encoded or transmited. This is refeard to as adaptive differntial pulse code modulation (ADPCM). PCM carrier systems employing this technique with an effective encoding rate of 32 kb/s are used in many digital transmission systems. These LBRE systems initially were used to provide private line voice service but are now widely deployed throughout the public network. The 32 kb/s ADPCM has many advantages over DSI systems but does not provide as much potential efficiancy and it does not provide good performance with voice band data applications. Also under development are 16 kb/s and 8 kb/s schemes. Subject to further studies, it is expected that these techniques will find additional apllications within the toll-network over the next few years because they have the potential to greatly increase the capacity of existing lightwave, digital radio and satelite systems. 4. The Local Subscriber Loop. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |~~~~~~~~~~~~| Feeder |~~~~~~~~~~~~~~~~~~| | End |___________________________| Servicing Area | | Office | | Interface | |____________| | (Cross-Connect) | ~~~~~~~~~|~~~~~~~~ | | /~~~~~~~~~~\ | Distribution A diagram of the basic | Pedestal |_______________/ Structure of the | | Local Subscriber \__________/ Loop. / | | \ / | | \ / | | \ Drop / | | \ (Service Wire) / | | \ / / \ \ / / \ \ /^\ /^\ /^\ /^\ /_____\ /_____\ /_____\ /_____\ | | | | | | | | |_____| |_____| |_____| |_____| . Your house.../ Some words from the 1st Phreak... 'Cables of telephone wires could be laid underground or suspended overhead, communicating by branch wires with private dwellings, counrty houses, shops, manufactories, etc., etc., unitting them through the main cable with a central office where the wires could be connected as desired, establishing direct communications between two places in the city.' -Alexander Graham Bell This description by Mr Bell himself, describes the basic structure of the customer loop as we know it today. Today telcos have spent over $50 billion, with the anual telco expenditure of $5 billion on the growth and maintance of loops. The phone set is supplied with direct current (DC) from a 48-volt batery supply in the end office over a pair of twisted copper wires. The 2 wires form a loop from the phone to the telepohne office, that's why it is called 'The Local Loop.' The bateries are backed up by a diesel generator at the local office, so if there is an electrical problem the system can still operate. The local loop provides you with access to the telecommunications network through the end office. In the US, the end office connects with the intereXchange carrier's point of presence (POP) either directly or through the phone company's access tandem. The local loop consists of a pair of insulated wires twisted together and combined with 100's of other twisted pairs in a single cable. These cables can be strung on poles, buried underground or installed in underground conduit. The diamater of the wire varies from 0.016 inch (26 gauge) to 0.036 inch (19 gauge): the thiner the wire, the higher the loss. In the late 70s and early 80s, digital subscriber carrier systems came into general use. The primary objectives of using digital carrier systems were to reduce the number of copper pairs required in the feeder portion of the customer loop and to limit the length of the distrobution portion of the loop to 12,000 feet or less. Providing a remote terminal at the end of the feeder section, operating over a digital carrier system, reduces the amount of twisted pair cable required and eliminates the need for reinforcing feeder routes to accomodate customer growth. DLC Remote Terminal or Remote Switching Terminal: 24-2,000 1.544 Mb/s Repeated Customer Lines T-1 Span Lines \ \ \ / / / / | | | | | | | | / | | | | | | | _______/ | | | | | | | / | | | | | | | / | | | | | | | |~~~~~| \|/ |~~~~~| |~~~~~~~~~~~~~~~|______|__>__|___________|__>__|______|~~~~~~~~~~~~~| |Remote Terminal|______|_____|___________|_____|______| CO Terminal | |_______________| | < | | < | |_____________| | | | |_____| |_____| | | | | | | / | Phone Example: Phone \ Phone * Concentrates 128 customer lines to 32 trunks between terminals * Each digital signal cariies 24 conversations on 2 cable pairs. Digital carriers systems allow 64-kb/s or higher-rate digital services to be provided on even the longest loops. Telcos are planning to provide fiber to home (FTTH), or fiber to curb (FTTC) in order to enter the video dostrobution market, this subject will be discussed later in the file in more detail. However, in order to squeeze the maximum bandwith out of the existing copper pair loop, a number of new technologies have emerged. Asymmetric digital subscriber lines (ADSL), in combinitation with the latest advances in digital video compresion, is now making it possible to transmit a digitaly encoded video channel over the existing twisted pair loop. Telco's are exploring several ASDL options called ADSL-1, 2 and 3. ADSL-1 will operate over nonloaded loop plant which extends to 18,000 feet. It will operate at 1.5 Mb/s and deliever a single channel of encpded video. The quality level will be equivalent to a VHS tape. ADSL-2, operating at 3 Mb/s, will extend to 12,000 feet. ADSL-3, operating at 6 Mb/s, has been proposed for loops upto 8,000 feet: Asymetric Digital Subscriber Line: Central Office Remote Terminal House |~~~~~~~~~~~~~| Fiber |~~~~~~~~~~| |~~~~~~~~~~~~~~~| | ADSL-2 |____________| ADSL-2 |____________| ADSL-2 3 Mb/s | T | | | | Copper |_______________| o | | |__________| | | <=========> | | | | N | | | | | e | | | TV Phone t | | | Fiber w | ADSL-3 | | o |_____________| | r | |~~~~~~~~~~| |~~~~~~~~~~~~~~~| k | | ADSL-3 |___________| ADSL-3 6 Mb/s | | | | Copper |_______________| | |__________| | | | | | | | | | | | |________________________|~~~~~~~~~~~~| TV Phone Copper | ADSL-1 1.5 | |____________| | | | | | | | | TV Phone The existing local loops support switched and dedicated digital services at speeds up to 64 kb/s. The loop also supports the ISDN digital subscriber line (DSL), which provides 2 64 kb/s 'beaver' channels (circuit switched). The DSL can extend up to 18,000 feet from the central office or a digital loop carrier remote terminal on nonloaded cable. A number of commercially available pair gain devices use DSL technology to double or quadruple the capacity of a given twisted pair in the loop. These pair gain devices use 64- kb/s or 32-kb/s encoding to achieve the pair gain. The high bit rate digital subcriber line (HDSL) is being widely used in the local loop environment, and is probably in use in your area. The HDSL provides a standard DS-1 rate signal up to 12,000 feet from the serving central office using 2 cable pairs and no repeaters. Shouts: ~~~~~~~ 9x, Substance, gr1p, DarkCYDE, Extreem, Chimmy, ELF, DownTime, ZerOnine Essance, Dialt0ne and finally PF BBS in London, Darkcyde (the person) Notice: ~~~~~~~ Sorry about the shortness of this file, I am in the middle of another file, which will contain the following: Switching Systems Public Packet Switched Networks PPSN The IRIDIUM Network PCS Personal Communications Services U.S. National and Regional Lightwave Networks SONET Synchronous Optical Network Protection Switching Phiber to Home Phreaking the Military, Secrets of 71o The Old AUTOVON Network Prefix assignments -+ Hybrid +- hybrid_blue@hotmail.com 'Technology has turned reallity into a paradox. Forms are not always as they seem. The strugle for non conformity has become even more complicated. Technology has learned to duplicate, rebuild, and remanufacture reality and humanity. The ability to take a template and replicate it is not a fantasy anymore, it is a threat. The strugle against conformity has become a comprehensive investigation into technology that works against the principle of individuality and non conformity. Humanity has become a relative term in the search for truth; A search for clues. A search for variables in life and mutation in a genus. -Fear Factory. 9x - spReading hP iN thE nEw mIllen1um 1998 (c) 9x Production, all rights lost ___ ___ _____.___.____________________ ____________ hybrid@b4b0.org / | \\__ | |\______ \______ \/_ \______ \ hybrid@ninex.com / ~ \/ | | | | _/| _/ | || | \ hybrid.dtmf.org \ Y /\____ | | | \| | \ | || ` \ ---------------- \___|_ / / ______| |______ /|____|_ / |___/_______ / \/ \/ \/ \/ \/