A

AAL (ATM adaptation layer), B-ISDN model, 319,350 AAL0, 351 AAL1, 351-353 AAL2, 353-355 AAL3 4, 355-360 AAL5, 361-363 CS, 319 SAR, 320 AAL-indicate bit, 310 ABR (available bit rate), 337-341 closed-loop flow control, 338 service category, 366 AC (access control) field DQDB slots, 380 SIP Layer 2 PDUs, 394 access classes, SMDS, 376 access signaling specifications, Frame Relay, 273 AD (Adjunct), 64 adaptation layer, 317 adaptive QAM (quadrature amplitude modulation), CAP, 416 Address Complete...

Aal0

AAL0 is not based on specifications or implementation agreements. It is simply a term to denote the input to the AAL of raw cells. AAL0 requires that user equipment provide its own proprietary or standards-based AAL functionality, resulting in fully compliant ATM cells from the higher layers. The main use of this AAL type is for equipment and applications that require an AAL type that is not compliant with the specifications, thus offering as input to the ATM process data structures that do not...

Aal1

AAL1 adapts CBR traffic, such as uncompressed voice and video, into ATM cells and is used for applications that are sensitive to cell loss, delay, and delay variation. In other words, AAL1 would be selected to transfer traffic with a constant source bit rate that must be delivered at the same rate. Because AAL1 must have timing synchronization between the source and destination, it must be implemented across a physical layer service that provides timing, such as SONET, or the timing must be...

Aal2

AAL2 provides for the bandwidth-efficient transmission of low-rate, short, and variable-length packets in delay-sensitive applications. More than one AAL2 user-information stream can be supported on a single ATM connection (multiplexing). Short-length packets can be packed into one or more ATM cells with AAL2. Used with time-sensitive rt-VBR traffic, such as compressed voice and video, AAL2 allows ATM cells to be transmitted before the payload is full to accommodate an application's timing...

Abr

The ABR service class is intended for non-real-time applications that have the capability of reducing and increasing their cell rate, based on network conditions, and that do not have strict delay requirements. ABR uses the bandwidth left over after connections using CBR and VBR service classes have registered for the bandwidth they need. Nevertheless, ABR does provide a minimum bandwidth guarantee, as the network will not establish the connection (CAC) if it cannot guarantee at least the...

ABR Service Category Definition

ABR is an ATM layer service category for which the limiting ATM layer transfer characteristics, which are provided by the network, can change subsequent to connection establishment. A flow-control mechanism is specified that supports several types of feedback to control the source rate in response to changing ATM layer transfer characteristics. This feedback is conveyed to the source through specific control cells called resource management cells (RM-cells). It is expected that an end system...

Access Control Field

SMDS uses the access control field similarly to the way it is used in DQDB. In a single-CPE configuration, the CPE sets the busy bit to 1 when data is being sent and 0 otherwise. Because there is no upstream from the CPE (there is only one), the REQ fields are always set to 0. The four do not care bits are reserved for use in isochronous transmission, and are not part of the current SMDS implementations. In the multi-CPE configuration, the REQ bits now come into play. If the SS receives an...

Access Signaling Specifications

ITU-T Q.933 and ANSI T1.617 deal with access signaling for Frame Relay. In this sense, these specifications represent a third layer to the Frame Relay infrastructure, much as Q.931, which is referenced heavily by Q.933, represents a third layer for ISDN. Nevertheless, the functionality of the Frame Relay network encompasses only the first two layers, as was previously stated. As with Q.931 for ISDN, Q.933 is involved with the specification of the procedures for the establishing, maintaining,...

Acknowledgments

There are so many people that need to be thanked and acknowledged for their contributions to this book, and their commitment to getting this book to press. First, I would like to thank the great folks at Cisco Press for their patience. John Kane, Michelle Grandin, and Drew Cupp have been patient and supportive with the particularly interesting schedule that this book has been on. Your hard work and occasional nudge to get the chapters moving faster helped make this a success. There are also...

Address Subscription

Even though SMDS addresses appear as phone numbers, they behave more like MAC addresses on LANs. Recall that SMDS was derived from DQDB as a mechanism for data exchange across MANs or WANs. Also recall that SMDS had unicast and multicast routing, address screening, and source address verification as design goals. For the SMDS service to provide these features, a mechanism is needed to allow for address subscription, so that customers can build SMDS networks that are flexible, easy to...

Addressing

SMDS provides an addressing mechanism based on ITU E.164 formatting, which essentially makes SMDS addresses look exactly like phone numbers. Each CPE can have multiple SMDS addresses (up to 16), which are used for unicast datagram delivery. Broadcast and multicast delivery is also provided through one or more group addresses that are associated with CPE. For security, address screening (AS) and source address verification (SAV) are available. Using AS and SAV, the SMDS network provider can...

Adpcm

What happens during the less common occurrences when the change between amplitudes of consecutive samples is not close enough to be represented adequately with DPCM Basically, the quantizing noise can be great. With DPCM, there is no mechanism to circumvent this situation, aside from encoding the actual sample, rather than what might have become an inaccurate prediction. Enter ADPCM. The adaptive part of ADPCM is an enhancement to DPCM. In general, everything works the same, but with ADPCM the...

ADSL Components

The physical ADSL infrastructure is made up of several components (see Figure 12-4). Each component plays a role in some aspect of the DSL connection. The following is a list of some of the most common components in a DSL environment DSL access multiplexer (DSLAM) DSLAM is the device that aggregates and terminates the DSL circuits. It contains multiple ADSL transmission unit central offices (COs) (ATU-Cs), and some type of network interface to uplink to the network access point (NAP). (See the...

Alarm Conditions

T1 alarm states are commonly referred to based on the colors of the lights that the original T1 equipment used to designate that particular alarm condition. Each of the three alarms discussed in this section are considered major alarms and are not usually declared for events that do not directly result in some form of failed signal state or OOF LOS condition. In fact, many manufacturers specify a set of minor alarm conditions that serve to alert administrators to the impending risk of a major...

Law Used in Europe and the rest of the world

These are known as companding algorithms because they effectively compress the PAM signal for error reduction on the transmitting end and expand the signal back to normal on the receiving end. Analog information that has been quantized by one algorithm becomes incompatible with equipment that uses the other. It is common to convert between the two standards for communication between conflicting equipment. The digital signal level 0 (DS-0) created by North American or Japanese equipment can be...

Analog Introduction

This chapter introduces terms and concepts commonly associated with analog communication. Topics covered in this chapter include a brief analog signal overview, analog signal composition, and different analog deployment methods. Although most of this book focuses on the different aspects of digital communication methods, an understanding of analog communication is essential to recognizing the fundamental differences between them and to building a strong foundation of knowledge. An analog signal...

Analog Service Deployments

Typically when you think about analog service, you imagine huge telecommunication corporations with hundreds of switches and millions of customers. This concept contains several general ideas about what the service provider or the public switched telephone network (PSTN) really is. Even if you are new to the industry, chances are you have been exposed to the infamous cloud. The cloud that encompasses anything and everything related to the service provider. These companies provide services to...

Anatomy of BRI

When configuring an ISDN device for BRI service, you must have the proper information for communication on the service provider's network. First and foremost, you need to know what type of switch you are communicating with. The switch type is important because not all vendors have implemented ISDN in the same way. For this reason, if you tell your equipment that it is communicating with a Lucent 5ESS, but you are actually connected to a Nortel DMS-100, you might not be able to access the ISDN...

Answers to Chapter 10 Review Questions

What is the difference between UNI and NNI Answer A UNI interface connects an ATM endpoint to an ATM switch, but an NNI interface connects two ATM switches together. 2. Why are there more available VPIs in an NNI header Answer There is no GFC in the header of NNI, which leaves four more bits for the VPI field. 3. What do you call a cell that is destined for one connection but because of an error has been delivered to a different connection 4. For what technology was ATM originally designed to...

Answers to Chapter 11 Review Questions

What were some of the major motivating factors for the development of SMDS Answer The RBOCs were looking for a data driven, connectionless service offering. B-ISDN standardization was moving at a snails pace. Further, the rapid deployment of client server applications and networks were driving an increasing need for highspeed LAN-to-LAN connectivity. 2. What are some common Layer-3 protocols that are supported over SMDS Answer All protocols that use LLC can be carried over SMDS. 3. At what...

Answers to Chapter 12 Review Questions

1.What are the encoding methods used for DSL Answer Quadrature Amplitude Modulation (QAM), Carrierless Amplitude and Phase Modulation (CAP), and Discrete Multi-Tone Modulation (DMT). 2. What are the three items that characterize analog carrier signals Answer Amplitude, frequency, and phase. 3. What frequency range does voice use in POTS Answer 0-4 kHz. 4. Into how many subchannels does DMT divide the bandwidth Answer 256. Answer A bridged tap is an unterminated telephone loop. 6. What is a...

Answers to Chapter 14 Review Questions

What is the function of an add drop multiplexer Answer The ADM can crossconnect and groom traffic at the DS1 or DS3 levels without the need to completely demultiplex the signal. 2. What is one basic difference between a BLSR and a UPSR Answer A BLSR uses both fibers for bidirectional transport, and thus must reserve half of the bandwidth for failover applications. A UPSR uses one fiber for active transport, and one for protection. 3. What is the purpose of the H1 and H2 bytes in the line...

Answers to Chapter 3 Review Questions

Which of the following are examples of the difference between analog and digital communication (choose two) a. The term frequency only applies to digital communication. b. The term bit rate only applies to digital communication. c. The quality of an analog signal is generally better than that of a digital signal. d. The quality of a digital signal is generally better than that of an analog signal. e. Circuits, and sending and receiving equipment, are identical in analog and digital...

Answers to Chapter 7 Review Questions

How many T1s are found in an unchannelized T3 Answer There are no T1s in an unchannelized circuit. This is a trick question. Remember that you must have a channelized circuit to split off any of the smaller circuits. 2. True or False. T3 circuits are generally considered to be synchronous, similar to T1s. Answer False. The T3 circuits employ an asynchronous multiplexing scheme, and although T1 circuits are synchronous, their relationship to each other is asynchronous. 3. How many 0s must be...

Appendix A Answers to Review Questions 530

Answers to Chapter 1 Review Questions 530 Answers to Chapter 2 Review Questions 532 Answers to Chapter 3 Review Questions 536 Answers to Chapter 4 Review Questions 538 Answers to Chapter 5 Review Questions 541 Answers to Chapter 6 Review Questions 543 Answers to Chapter 7 Review Questions 545 Answers to Chapter 8 Review Questions 546 Answers to Chapter 9 Review Questions 548 Answers to Chapter 10 Review Questions 549 Answers to Chapter 11 Review Questions 551 Answers to Chapter 12 Review...

Associated Signaling

Associated signaling occurs when your call and signaling take the same path, but the signaling is not obtrusive to the actual bearer traffic. Figure 2-6 shows an associated signaling link between two SS7 SSPs. Several technologies use this methodology. The TDM-based E1 can use timeslot 16 (TS16) as its signaling channel for CCS signaling, such as ISDN PRI or SS7, and although the signaling is physically in-band, it's logically out-of-band because it does not directly interfere with the data...

ATM and BISDN

ATM is a cell-switching (actually packet-switching, such as X.25 and Frame Relay) technology that quickly switches fixed-length frames through a network infrastructure that is finely tuned to QoS parameters. ATM allows every manner of digitized traffic to be transmitted with attention to priority, based on delay sensitivity and other special requirements. ATM can be thought of as a more refined version of Frame Relay. Frame Relay allows frames, with almost any length up to 1600 octets, and ATM...

ATM Functionality

This section details the technical foundation for ATM. In subsequent sections, you will see the five-octet header formats used with ATM. You will then see ATM as a layered model, much as any other layered approach to comprehending a protocol by classifying and ordering its core components, after which you will be presented with a discussion on topics that deal with how user information is adapted for cell production and how different traffic is classified for QoS treatment. Generally speaking,...

ATM Header Components

It is imperative to understand the functions of the fields in the ATM header to fully understand how ATM operates. Figure 10-2 shows formats of the headers for the UNI and NNI interfaces explained earlier in the ATM Functionality section. It is not uncommon to see the UNI specification used throughout a virtual circuit, but the NNI format is never seen between an endpoint and switch. The entire list of fields in both headers follows Generic flow control (GFC) (4 bits on UNI absent on NNI)...

ATM Layer

On an outgoing basis, the ATM layer accepts already-segmented 48-octet data units from the pertinent AAL and places the five-octet headers on them. The process is reversed for incoming cells. As a result, VPI VCI awareness is a function of the ATM layer. In fact, the ATM switch uses this layer's functionality to perform VPI VCI translation, as the cell traverses the switching fabric. It is this layer that performs the switching (or cell relaying) within the network and that provides the final...

B

B8ZS (bipolar 8-zero substitution), 133 BACP (bandwidth allocation control protocol), 243 BAP (bandwidth allocation protocol), 243 BASize field (SIP Layer 3 PDUs), 387 BE (Beginning-End) Tag fields, SIP Layer 3 PDUs, 386 Be (excess burst size), 282 bearer capability IE (Q.931 messages), 234-236 bearer channels, DSL, 427 bearer traffic, 22 Bellcore, role in SMDS development, 373-374 BERT (bit error rate test), 143-144 B-ICI (Broadband Inter-Carrier Interface), 304 billing methods, ISDN BRI,...

B3T Line Coding

International BRI circuits, commonly called ISDN-2 or ISDN Basic Access (IBA), use a different type of line coding that is called 4 Binary 3 Ternary (4B3T). This coding scheme is a bit more complicated than most and is also referred to as Modified Monitoring State Block Code 43 (MMS43). The basic premise is to take four binary digits and, using a lookup table, convert them to be used in a strict three voltage state environment of negative, zero, and positive voltage. This function creates an...

Basic E1 Controller Configuration

To access any type of controller for configuration, you have to be in global configuration mode. After you are there, select the appropriate E1 controller. Example 6-1 shows the commands required to configure an E1 controller for normal operation. Example 6-1 Configuring an E1 Controller for Normal Operation 2600-1(config) controller el 0 0 2600-1(config-controller) framing no-crc4 2600-1(config-controller) linecode hdb3 2600-1(config-controller) clock source line primary...

Beyond the X3 Barrier

The big question is, is there anything after T3 and E3 The answer is yes and no. Both the NADH and the ITU hierarchy structures have levels of digital signals that exceed the T3 and E3 bandwidth levels. The NADH has four levels total in the hierarchy. After DS3, you normally only see documentation on one other bandwidth rate. It is called DS4 (T4), and it runs at a bandwidth rate of 274.176 Mbps. It is composed of 4032 DS0 circuits or six T3s and is by far the most bandwidth offered outside of...

Bibliography

For your reference and further study, this appendix contains a list of the resources that the authors used to write this book. af-bici-0013.003, BISDN Inter Carrier Interface (B-ICI) Specification Version 2.0 (Integrated), 1995 af-cs-0167.000, Guaranteed Frame Rate (GFR) Signaling Specification (PNNI, AINI, and UNI), Version 1.0, 2001 af-sig-0061.000, ATM User-Network Interface (UNI) Signalling Specification Version 4.0, 1996 af-tm-0056.000, Traffic Management Specification Version 4.0, 1996...

Binary Docsis Configuration Files

Most operational parameters that are transmitted to a cable modem as it initializes are contained in a binary configuration file in a type-length-value (TLV) format as defined in the DOCSIS specification. The DOCSIS 1.0 specification and DOCSIS 1.1 specification each define a configuration file format and parameters that are contained in the file. As a rule, the information contained in the DOCSIS 1.1 configuration file is a superset of that contained in the 1.0 configuration file. Although...

BRI Capabilities and Features

ISDN BRI can support up to eight devices on the S T bus, but you are limited by the number of B channels that your circuit has. Most service providers don't tell you this, but if you have two B channels with your ISDN service, you can only use two devices at any one given time. After both B channels are in use, you cannot add any other services without disconnecting something. So if your ISDN TA is using both B channels for a data call and you want to place or receive a voice call, you have to...

BRI Circuit Provisioning

Each BRI circuit is provisioned into the switch framework. The provisioning on the BRI circuits is completed through capability packages. The capability packages, also called ISDN Ordering Codes (IOCs), offer different combinations of bandwidth and service. Not only can the physical characteristics change (1B+D, 2B+D, just D), but the service types also can be modified. That means that a circuit can be provisioned for just voice, just data, or a combination of the two. These capability packages...

BRI Operation

ISDN BRI circuits are always active and use a type of heartbeat to maintain circuit status. On a standard BRI installation, if you plug an analog phone into your ISDN jack you can hear an intermittent click. That click is a good way to see if you are getting an ISDN signal. If you can hear the click, your service is turned on. That doesn't mean that there isn't a problem with the service, just that you have it. The main selling points for BRI service are that there is increased bandwidth over...

Bursty Errors

Bursty errors are multiple errors that occur in short timeframes. For example, in a 1-minute timeframe, there might have been a total of 100 errors, but the 100 errors occurred in bursts of 10 errors at a time, spaced several seconds apart. To determine if errors are bursty, inspect the total DSL trained-up time and errored-seconds counters. If a unit has been trained for 1 hour, has reported 100 errors, and 1 errored second, the errors are bursty. If the unit has been trained for 1 hour, has...

Cable Length

When everything in the cable system is working perfectly, the most significant factor related to DSL service is cable length. As cable length increases, the gauge (diameter) of the wire becomes increasingly significant, and interference from other services in the same cable become more apparent. Longer cable lengths attenuate all signal frequencies, although more attenuation occurs at higher frequencies than at lower frequencies. This is due primarily to the distributed capacitance along a...

Called and Calling Party lEs

The calling and called number IEs specify the originating and destination numbers associated with the call. The numbers can be a variety of coding structures but are generally seen as ITU E.164 numbers, which mimic telephone numbers. Figure 8-19 shows the formats associated with the calling and called party IEs. Figure 8-19 Calling and Called Party IE Format Called Party Number The called party IE contains several significant fields. The type of number field describes what kind of number the...

Capability Set 1 CS1

CS-1 is the first capability set that was used with the IN architecture. It was designed to support all developing IN services and to set the framework for compatibility of future service offerings. CS-1 also takes into account that there are proprietary services that do not necessarily go through ITU-T's process for standardization. The CS-1 standard describes two different types of services Type A and Type B. Type A service is what is known as a single-ended service. In other words, if the...

Capability Set 3 CS3

CS-3 is the newest set of features to be added to the IN infrastructure. CS-3 is the next generation of IN functionality that builds upon what is already in place from CS-1 and CS-2 in the service provider network. Some of the services that are added with CS-3 are the following Feature interworking Features can now interoperate with one another, which allows for multiple simultaneous services to be deployed to the subscriber at one time or over one call. Number portability Number portability is...

Cbr

An AF term, CBR is known as the deterministic bit rate (DBR) service class in ITU-T recommendation I.371. CBR connections are requested by sources that require a static amount of bandwidth that will be unwaveringly available during the lifetime of the connection. The amount of bandwidth required is communicated through the PCR value during call setup. The network guarantees the negotiated QoS to each and every cell that conforms to the pertinent conformance tests. This commitment is applicable...

Cdvt

During the normal operation of the ATM layer, which is where the multiplexing of cells from different sources occurs within network switching devices, switches can change the characteristics of the traffic in comparison to the expectations associated with its original connection. In particular, CDV can be introduced, which affects the peak emission interval (recall, 1 PCR), and the sustained emission interval (1 SCR). See the Traffic Management section later in the chapter for a detailed...

Channel ID

The next IE you will see in an output is the channel ID. The channel ID (as with all of the output in a Q.931 debug), is listed in hexadecimal format, as shown in Example 8-3. Example 8-3 Q.931 Call Setup Showing the Channel ID Value TX -> SETUP pd 8 callref 0x04 Bearer Capability i 0x8890 Channel ID i 0x83 Called Party Number i 0x80, '9195551212' RX < - CALL_PROC pd 8 callref 0x84 Channel ID i 0x89 RX < - CONNECT pd 8 callref 0x84 TX -> CONNECT_ACK pd 8 callref 0x04____ Cisco IOS will...

Channelized and Unchannelized T3

Asynchronous T3 circuits have two modes that they can be leased in channelized or unchannelized. The difference between the two of them is rather simple. The channelized T3 is composed of 28 T1s (672 DS0s) and has all the associated overhead and bit stuffing. Unchannelized T3 circuits are composed of a single, non-multiplexed DS3 signal. Because unchannelized T3 has no bit stuffing or overhead, all the bandwidth is available for user transmission. A T3 is clocked at 44.736 Mbps. A channelized...

ATM and BISDN 300

The Development of ATM and B-ISDN 300 Standards Bodies and the ATM Forum 301 ATM Header Components 305 GFC 306 VPI 306 VCI 306 Payload Type (PT) and OAM Cells 309 CLP 313 HEC 313 The B-ISDN Reference Model and ATM 316 Physical Layer 318 ATM Layer 319 AAL 319 QoS 320 CLR 323 maxCTD 323 Peak-to-Peak CDV 325 CER 325 SECBR 326 CMR 326 Traffic Parameters 327 Peak Cell Rate (PCR) 328 Sustained Cell Rate (SCR) 328 Maximum Burst Size (MBS) and Burst Tolerance (BT) 329 Minimum Cell Rate (MCR) 329...

Cable Modem Technology and CATV 446

The Hybrid Fiber-Coaxial (HFC) Network 449 Headends and Hubs 450 International Television Standards 451 Frequency Allocation 451 Requirements for Cable Plant Quality 453 Common Cable Plant Issues 454 DOCSIS The Cable Modem Standard 456 DOCSIS and Euro-DOCSIS 457 Modulation Types 458 Error Mitigation Through FEC 459 Error Mitigation Through Interleaving 460 Moving Picture Experts Group (MPEG) Framing 461 Throughput for DOCSIS and Euro-DOCSIS 461 DOCSIS Media Access Control (MAC) Domains 463 SID...

The Signaling System 7 Network

Signaling Introduction 22 What Is Signaling 22 SS7 Node Types 23 SSP 23 STP 27 SCP 27 Associated Signaling 29 Quasi-Associated Signaling 30 Non-Associated Signaling 31 Signaling Links and Link Sets 33 Link Categories 35 Originating, Destination, and Adjacent Point Codes 38 North American Point Code Format 39 ITU Point Code Format 40 SS7 Upper-Layer Protocols 54 DUP 54 TUP 56 ISUP 58 Intelligent Network (IN) 62 FEs 62 PEs 63 Capability Set 1 (CS-1) 65 Capability Set 2 (CS-2) 66 Expert Whiteboard...

T3 and E3 Technology 180

Evolution of the North American Digital Hierarchy 181 Synchronous or Asynchronous 182 Channelized and Unchannelized T3 182 Sorting out the Mess 184 Deployment Options 193 T3 Line Coding 194 T3 Framing Types 195 Configuration of a Channelized T3 Interface on a Cisco 10000 ESR 198 Evolution of the International Digital Hierarchy 199 Sorting out the Mess 199 Unchannelized E3 Frame Structure and Operation 202 Configuration of an E3 Interface 205

Integrated Services Digital Network 212

The ISDN Network 213 Circuit Switching 213 The Local Loop 215 Echo Cancellation 216 Network Interface Device (NID) 217 ISDN Reference Points 218 ISDN Specifications 219 ITU Q.921 220 ITU Q.931 229 SS7 and ISDN 240 Configuring a T1 and E1 PRI Connection 258 Resolving Issues with ISDN PRI 259 Q.Sig 260

Frame Relay 266

Standards Bodies and the Frame Relay Forum (FRF) 268 Frame Relay Specifications 271 Framework Specifications 271 Service Description Specifications 271 Core Aspects Specifications 272 Access Signaling Specifications 273 FRF Implementation Agreements 273 Frame Relay Functionality 275 VCs 275 Contractual Values in Frame Relay 282 Frame Discards and Recovery 284 Signaling 286 Frame Relay Configuration on Cisco Devices 292

Chapter Summaries and Review Questions

The Summary and Review Questions sections at the end of each chapter are designed to reinforce some of the most important topics that are discussed in that chapter. Use them to assess your understanding of the chapter's subject and then review as necessary. The review questions are in multiple choice, lab-based, and fill in the blank format. The answer for each question is discussed in detail and explained for complete understanding. You can find the answers to the review questions in Appendix...

Clr

The CLR is defined as the ratio of lost cells to the total number of cells transmitted. For the computation of the CLR, the counts for lost cells and transmitted cells should not include those cells that were counted as members of severely errored cell blocks (to be discussed shortly). The CLR parameter is the value of CLR that the network agrees to offer as an objective over the lifetime of the connection, not an instantaneous or short-term measurement. It allows network devices to decide...

Comparison of SONET and SDH Hierarchies

SONET and SDH have emerged simultaneously as optical network standards that are used throughout the world. Several basic differences exist between the hierarchies, but they do not cause incompatibility. On the contrary, the international community has strived for compatibility between the North American SONET hierarchy and its own SDH hierarchy. Before you look at the optical hierarchies, it is important that you understand the differences in multiplexing between synchronous and asynchronous...

Configuration of a Channelized T3 Interface on a Cisco 10000 ESR

This section focuses on the configuration of a channelized T3 interface for a Cisco 10000 ESR. This expansion card is normally used for channelized applications, but it can be used in an unchannelized mode, if necessary. Each CT3 card has a total of six T3 ports, each denoted by a Tx and Rx pair of 75-ohm female BNC connectors. This basic configuration gives you an idea of some of the things that you can configure on the card. For more information on the topology, refer to Figure 7-12. The T3...

Configuration of an E3 Interface

The following example is based on Cisco PA-MC-E3 Multichannel E3 port adapter, on a Cisco 7500 router. This adapter provides one channelized E3 high-speed serial interface. According to information posted on Cisco Systems' web site, the PA-MC-E3 has one channelized E3 high-speed serial interface that provides access to services at E1 (2.048 Mbps) data rates. Also from the same source the PA-MC-E3 complies with CCITT ITU G.703 physical layer standards and CCITT ITU G.751 for E3, G.742 for E2,...

Configuring a Cisco Router for DDSSW56

This section details how to configure a Cisco router with a WAN interface card (WIC)-1DSU-56K4 for DDS or SW56 operation. Just as you do with the test patterns, you must enter the proper serial interface that is associated with your WIC for DDS SW56 configuration From this interface you can begin to configure the DDS circuit. The first command to enter is whether you are using DDS or SW56. If you use switched, you also have to specify dialer in-band for the dialing method Router(config-if)...

Configuring a T1 Controller

This section gives two examples of how to configure a T1 controller on Cisco networking devices. To access the T1 controllers for configuration, you have to be in global-configuration mode and then select the appropriate T1 controller. Example 5-1 shows the simple configuration of a T1 controller for ESF framing and B8ZS line coding. Additionally, the controller is being configured to supply equalization (gain) for cables up to 133 feet. Example 5-1 Configuration of a T1 Controller router...

Configuring a T1 Hairpin

Figure 5-8 shows the use of a drop and insert function, which is also referred to as a hairpin connection. This allows you to redirect timeslots and then drop out the remaining timeslots to another device. Here, timing is important to remember because the same circuit's DS-0s travel through multiple devices. In Example 5-2, the clock source internal command at the end of the controller t1 0 1 configuration is necessary if this controller will be providing the timing to the device at the other...

Configuring Isdn Bri

The first of two types of ISDN that you will configure is ISDN BRI service. Make sure that before you go to set up your ISDN TA, you have the proper ISDN switch type, your SPIDs, and any telephone numbers that are associated with your circuit. You will be configuring a basic BRI application by using a Cisco router. Figure 8-25 shows a diagram of the network that you will configure in this example. Figure 8-25 BRI Configuration Example ISDN Switch Type NI1 Figure 8-25 BRI Configuration Example...

Connection Status

Connection status is only one of four extensions to the Frame Relay standards, known collectively as the LMI specification. The following list is from Cisco's Univercd web site Troubleshooting Frame Relay Connections (www.cisco.com univercd cc td doc cisintwk itg_v1 tr1918.htm) and presents these four extensions and a brief description of each. The remainder of this discussion is mainly about status messages. The term common means that a standards-based implementation of Frame Relay has this...

Contents at a Glance

Chapter 1 An Overview of Analog Communication Chapter 2 The Signaling System 7 Network Chapter 3 Analog-to-Digital Conversion Chapter 4 Digital Dataphone Service and Switched 56 Chapter 6 E1, R2, and Japanese Carrier Technology Chapter 8 Integrated Services Digital Network Chapter 11 Switched Multimegabit Data Service

Core Aspects Specifications

The specifications that deal with the core aspects of Frame Relay are ITU-T Q.922 and ANSI T1.618. Parenthetically, be careful not to get drawn into an office argument over the ANSI specifications. You might be used to higher-level specifications having higher numerical components in their naming, but ANSI throws you a curve with T1.618 and T1.617. Although ITU-T's corresponding specifications are numbered in logical order (Q.933 is higher level than Q.922), ANSI reverses their numbering,...

Country ACountry B

A national SSP is a SSP that is located within a country which only communicates with other switches within that country. An international SSP is a SSP that is responsible for the routing of calls between different countries. There is also a hybrid SSP that functions at both national and international levels. This SSP can be considered an international gateway and has point codes associated with both networks. Each country should have at least one international gateway SSP to enable the smooth...

Cpe

The CPE segment is made up of the equipment at the customer or remote site. This equipment consists of ATU-R and possibly a POTS splitter, and it provides the DSL uplink to the NAP. The ATU-R is a self-contained unit that is deployed at the customer premises or the remote site. The ATU-R is a standalone unit that consists of an ADSL modem, an Ethernet or USB interface, and an AC power supply. The ATU-R can function logically as a router or a bridge, depending on its make and model. It can also...

CRC32 and CRC32 Indication Bit Fields

The CRC-32 field was originally specified in early 802.6 drafts however, its use was later deprecated when it was decided that the 10-bit CRC carried in each DMPDU segment was sufficient for detecting errors. Today, it is required that an SMDS CPE generate a 32-bit CRC using the formula specified in 802.6 however, a receiving station need only recognize that the field is present. CRC calculations are performed by passing the bitstream through a circular shift register, which acts as a binary...

CRC4 Framing

CRC-4 framing uses a CRC to verify the integrity of the framing sequence. When you use CRC-4 framing, the frames are broken down a bit differently. CRC-4 framing splits each MF16 into two equal segments, often called submultiframes. The first submultiframe groups frames 0 through 7, and the second submultiframe groups frames 8 through 15. Within each submultiframe, the even frames (0, 2, 4, 6, and so on) place the CRC bits in the first bit position. CRC bits located in 0, 2, 4, and 6 act as a...

Crosstalk

The electrical energy transmitted across the copper wire line as a modulated signal also radiates energy onto adjacent copper wire loops that are located in the same cable bundle. In the telephone network, multiple insulated copper pairs are bundled together into a cable that is called a cable binder. Adjacent systems within a cable binder that transmit or receive information in the same range of frequencies can create significant crosstalk interference. This is because crosstalk-induced...

D

DA (Destination Address) field (SIP Layer 3 PDUs), 387 DACs (digital-to-analog converters), 10 DACS (Digital Access and Crossconnect System), 497 data-link layer functionality, Q.921 specification, 220-224 alignment process, 224-227 timers, 227-228 DB-15 connectors, 157 DBR (deterministic bit rate), 333 dBs (decibels), 7 logarithmic signal gain loss, 131 mid-span repeaters, 216 DDS (digital dataphone service). See also SW56 circuit deployment, 105 circuit testing patterns, 117-118 Cisco router...

D3 and D1D Channel Banks

While AT& T was attempting to produce a cheaper D1 channel bank, they discovered that much of the technology of the D2 channel bank also needed to be included. As a result, the D3 channel bank was suitable for long-haul connections, as was the D2. Similar to the D1, the D3 only operates on 24 channels. Unlike the D1, the D3 does so in a single stream, which precludes the need for interleaving non-consecutive channel-bytes. Nevertheless, an upgrade was made available to give D1 channel banks...

D4 Channel Banks

The SF format is also referred to as the D4 format, even though the D4 channel bank was not the first to provide SF functionality. The main impetus for the creation of the D4 channel bank was the 48-channel T1C (DS-1C) circuit that AT& T was concurrently designing. Also employing the SF format and -255 companding, the D4 channel bank standardized what we consider the channel-byte sequencing in use today, while allowing selectable backward compatibility with the previous models. The D4...

Dasa

Now comes the interesting part addressing. The DA and SA fields are used in the same way that a postal address is used on a letter, or that a MAC address is used on a LAN. Both the DA and SA fields are 64 bits long, with 4 bits of address type and 60 bits of address. The address type field denotes whether or not the L3_PDU is individually or group addressed. If the address type 1110, the address is a group address. If it equals 1100, it is an individual address. An L3_PDU received with any...

DB15 connector

If using twisted pair, you are using pins 1, 2, 4, and 5 of the modular plug. Pins 1 and 4 are a pair, as are pins 2 and 5. Similar to T1, to make a cross over you cross pins 1 and 4 and cross pins 2 and 5. If using balanced coax cable, you most likely have two BNC connectors one for Tx and one for Rx. DB-15 connectors are more common with T1 deployments, but you can use them with E1 circuits. A DB-15 connector has 15 pins and is similar to a monitor cable connector. DB-15s are only found...

Deployment Options

Depending on what equipment you use, several different interfaces are commonly found with T3 and E3 circuits. The most likely interface that you are to come across is 75-ohm coaxial cable. The deployment of coaxial cable for T3 generally comes in the form of two separate cables one for transmit (Tx) and one for receive (Rx). T3 and E3 circuits are high-bandwidth circuits that standard twisted copper pair cannot normally support. For example, most deployments of T3 E3 circuits today actually...

Detection of Data Errors

The frame-check sequence (FCS) field is an error detection mechanism that determines if the data in the frame in question has been compromised during its most recent leg of transmission (such as from switch to switch). The FCS is a computed value that is inserted into this position in the frame. The receiving device computes a value by using the same algorithm, the result of which should be identical to the inserted value. If there is a discrepancy, it is assumed that the frame was damaged...

Digitalto Analog Converters

DACs convert between digital and analog signals. Two common implementations of this type of equipment are modulator-demodulators (modems) and the conversion that is applied at the CO for each analog circuit. A modem converts the unipolar digital signals that are transmitted by your computer into an analog signal stream. A unipolar signal is a signal that has only a single voltage polarity. So, instead of having both positive and negative sides to a signal stream, only a positive or negative...

Dlci

The DLCI is a 10-bit (1024 possible values larger DLCIs are allowed by the standards, but not common) numerical value carried in each Frame Relay header. The DLCI signifies the VC to which the frame belongs and helps determine the physical path to be taken out of a device to allow the frame to continue along the same VC. Similarly, the originating device uses the DLCI to inform the ingress switch of the VC over which the customer intends or requires the frame to be transmitted. Refer to Figure...

DLCIs

Frame discards and recovery These points expanded to include in-depth discussions of the Frame Relay header and the use of special fields within the header, including how some of these fields relate to the optional feature of network congestion control. The signaling portion of this section was further expanded to include details on the following points Signaling bits for congestion Finally, you were shown a sample configuration for a public Frame Relay implementation.

Docsis Cable Modem Initialization Sequence

When a DOCSIS cable modem is connected to a cable IP network and powered on, it has no information regarding the network on which it is placed. As part of the overall design for cable modem portability between networks, cable modems must come online with no prior knowledge of specific network conditions. Most specifically, the cable modem has no knowledge of the channels and frequencies on which DOCSIS or Euro-DOCSIS communication is occurring. The DOCSIS modem initialization process is...

Docsis The Cable Modem Standard

A bi-directional cable modem technology must take into account existing CATV networks and CATV network quality and requirements for supporting IP networks. Although several proprietary cable modem network technologies exist, the internationally accepted (and by far the most popular) standard for cable IP networking is DOCSIS. Created by the MCNS to drive superior cable IP technology and to encourage competition between equipment vendors, DOCSIS and the analogous European standard Euro-DOCSIS...

Downstream Signaling and Transmission

Transmission of data in the downstream from the single downstream source (the CMTS) is through time-division multiplexing (TDM), wherein traffic bound for each cable modem is transmitted in a particular time slot that is determined by the CMTS at the time of transmission. Transmission capacity downstream is shared adaptively by traffic streams depending on demand. Downstream transmission is therefore dependent on QoS parameters, other parameters such as queuing algorithms, and vendor-specific...

Dxi

Recall from earlier in the chapter that most CPE vendors were not interested in developing the full SIP stack. This was partly because the vendors were concerned about forcing their customers to upgrade to the new hardware that would be required to implement the full SIP, which could result in stranded investment. On the other hand, the CSU DSU vendors saw this vendor disinterest as an opportunity to expand their product lines. The fact that these opposing sentiments created an opportunity for...

Dynamic Host Configuration Protocol DHCP Request Response

After power ranging is complete, the modem, now capable of Layer 1 and Layer 2 communication, establishes Layer 3 (IP) connectivity. IP connectivity is accomplished with the aid of DHCP. DHCP is widely used in IP-based systems to supply dynamic IP addresses and other network configuration information to IP-enabled devices. DOCSIS networks use standard DHCP systems (as defined in RFC 2131) to configure cable modems with IP addressing and other network information. When the cable modem begins the...

E1 Framing

E1 frames are larger than their T-Carrier counterparts. The E1 frame has a total of 256 bits (8 bits * 32 timeslots). Instead of grouping frames into segments of 12 Superframe (SF) or 24 Extended Superframe (ESF), E1 circuits group frames into clusters of 16. This is known as a Multiframe 16 (MF16). Each MF16 is 4096 bits long. Within each MF16, even and odd frames serve different purposes. Even frames control actual frame alignment and odd frames identify circuit alarms. Several different...

E1 Introduction

If you work in North America, you may or may not have ever had any exposure to an E1 circuit. E1 is the Level 1 digital signal that is found in the International Digital Hierarchy developed by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T, formerly CCITT). Most countries around the world use E1 circuits, with the exception of North America and Japan. Parts of Korea, Taiwan, and Hong Kong also use T-Carrier interfaces, although this use is decreasing...

E12 Multiplexing

E12 multiplexing is the process of taking four international DS1 circuits (E1) and multiplexing them into a single international DS2 circuit (E2) (Figure 7-13 shows the process). This process is identical to the one described for M12. The multiplexing method is cyclic bit-interleaving with positive justification (ITU G.742), which means that the payload is built by taking one bit from the first E1, one bit from the second E1, and so on. The positive justification is what was described earlier...

E23 Multiplexing

The next order of multiplexing in the international digital hierarchy is E23. E23 multiplexes four E2s into a single E3 circuit. This process is identical to the one described above for E12. Cyclic bit interleaving is used, as per ITU G.751. This time, the payload is built by taking one bit from each E2 in sequence. The C-bits have the same purpose but at the E2 level now. Figure 7-14 shows the E3 frame format, and Figure 7-15 highlights the bandwidth computation. Each E2 has a total bandwidth...

Encoding

The final phase of the conversion process is one that this chapter has been alluding to for a while. This is what it's all about. After this phase, you have a stream of binary digits that is the digital traffic for transmission across the digital circuit. First, you need to understand that the term encoding, as it is used here, does not mean the same thing as encoding when it applies to transforming a bit stream into pulses of electricity. That type of encoding is discussed in chapters relating...

Error Mitigation Through FEC

Noise and interference levels fluctuate on cable networks and as a result even the most noise tolerant modulation scheme that is deployed on a cable plant with standard specifications will experience losses. FEC is one mechanism by which errors in transmission can be repaired upon receipt by the receiving device. The DOCSIS specifications include ReedSolomon (RS) FEC as a mechanism for loss mitigation. FEC works by placing binary information into a two-dimensional array and then determining...

Ethernet Aggregation Architectures

Several MSOs use an aggregated Ethernet approach to connect multiple CMTS devices, typically to a high performance switch. This is accomplished usually by either a set of multiple 100BT load sharing Fast Ethernet connections or through one or more Gigabit Ethernet connections. This simple approach to aggregating CMTSs, a switched Layer 2 approach, is popular because it is easy to understand and configure. Often the Ethernet aggregation approach is inexpensive, too. However, Ethernet media...

Evolution of Digital Communication

The idea was that analog information could be represented as distinct pulses of information, like Morse code, where only a few simple combinations are combined to represent a larger, more complex set of symbols. After conversion, analog information is stored and retrieved with more accuracy and quality than by directly recording analog information. The idea arose early on to use a bi-state mechanism as the combining element for digital communication. This was the dawn of what is now known as...

Evolution of the International Digital Hierarchy

The specifications from the International Telecommunication Union (ITU) on digital hierarchy match the NADH only in theory and the first digital signal level. From there, they deviate in data rates, management capabilities, line coding, framing, and just about everything else. The first level of the ITU digital hierarchy is the E1 circuit. Running at 2.048 Mbps, this circuit contains 32 DS0s. For more information on E1, refer to Chapter 6, E1, R2, and Japanese Carrier Technology. The second...

Expert White Board ATM QoS

In recent years, private businesses and governments have invested greatly in information technology to improve turnaround time in services, to facilitate access to their service anytime of the day from the comfort of there customer's home, and to cut costs by automating the office environment and combining networks. In the past, business and government had at least two networks A data network to provide connectivity among the mainframe, servers, and personal computers TDM switch network to...

Expert Whiteboard LNP Operation in North America

The Telecommunications Act of 1996, which became law on February 8, 1996, was designed in large part to open local exchange markets to competition by removing existing statutory, regulatory, and operational barriers that have thwarted the ability of new entrants to provide competitive, local telecommunications services in the U.S. One of the most significant steps that Congress took to effectuate this goal was to require all local exchange carriers (LECs), both incumbents and new entrants, to...

F

FCC First Report & Order, 69 FCS (frame-check sequence) field DXI, 404 Frame Relay packets, 285 FDM (frequency-division multiplexing), 127, 450 FEBEs (far-end block errors), 161, FEC (forward error correction), 422-423, 459-460 interleaving, 423-424 FEs (functional entities), 62 FEXT (far-end crosstalk), 9, 435 F-GCRA (Frame-GCRA), 349 fiber-node combining, 482-484 fiber-optic cabling, 501, 504, 522 fields of ATM headers, 305 CLP, 313 GFC, 306 HEC, 313, 316 PT, 309-313 VCI, 306-308 VPI, 306...

Frame Discards and Recovery

There is a simple rule that makes Frame Relay so elegant in its simplicity if there is a problem, discard the data. The two main causes for data being discarded are as follows Figure 9-7 shows the Frame Relay header in the context of an entire frame. The flag field at the beginning and end of the frame is the high-level data link control (HDLC) flag (0x7E). This is 01111110 in binary. As in the case of all protocols that rely on the HDLC flag to herald the beginning and end of a frame, Frame...

Frame Relay

Frame Relay is a packet-switching service that is widely used throughout the world today. Multiple standards bodies have written specifications for Frame Relay many vendors support each of these specifications in their hardware and software. This chapter covers the history of Frame Relay and the intricacies of its design and usage. Frame Relay, unlike T1, digital dataphone service (DDS), and plain old telephone service (POTS), is a packet-switching service and not a physical circuit. Frame...