Cisco Remote Connection Products

This chapter covers the selection of products for the central office, the branch office, and the SOHO or RO. The key is to know where product families fit, not to memorize individual product part numbers or codes. For instance, you can get by knowing the capabilities of the 3600 product family as compared to the 1600 product family, without getting into the granular details of either. The bulk of the information in this chapter leads the engineer to ask the right questions when embarking on a...

A

The only protocol or configuration attributes configured on the physical interface are the individual commands that make the BRI interface a part of the rotary group and the encapsulation. On dialer pool interfaces, you can set a priority to specify the order in which the interfaces are used. With rotary groups, that granularity is not possible. All protocol attributes are entered at the logical dialer interface configuration level. The use of dialer profiles versus rotary groups comes down to...

AAA Authorization

Once a user has been authenticated, he or she can be further restricted in what he or she is allowed to do. This is done using the aaa authorization command. These restrictions can be applied to activities or services offered on the router. As with the authentication, it is easier to see an example before diving into each option available. The syntax is quite simple and declares which activity or service (network, exec, command level, config-commands, and reverse-access) is being attempted and...

AAA Configuration

AAA configuration is implemented in three steps Step 1 Enable AAA Configuration on the router. During the declaration of AAA, the router must be told if it will be speaking with a Terminal Access Control Access Control System (TACACS) or RADIUS server. Step 2 Define who will be authenticated, what they are authorized to do, and what will be tracked in the database. Step 3 Enable or define the method on the interface. The following sections detail how to turn on AAA (Step 1), how to define the...

Additional Configuration Options

In some cases, you must tweak the default settings of an X.25 installation based on service provider mandates or customer requests. There are a number of items that can be configured to change the way in which X.25 operates Range of VCs Incoming, outgoing, and two-way circuits are possible options. Packet size Inbound and outbound packet size can be specified on the interface. Window size Inbound and outbound window size can be specified on the interface. Window modulus This is the limit of the...

Answers to Chapter 2 QA Section

1 What are the selection criteria for selecting a router platform Availability, bandwidth, cost, ease of management, applications and traffic patterns, backup needs and QOS, and access control requirements are the selection criteria. 2 Which of the following does not affect the installation of a router The answer is d, router port density. The router, and thus its port density, is selected after the requirements are established. 3 Of the 3600, 4800, 5300, and 7100 series routers, which provides...

Answers to Chapter 3 Do I Know This Already Quiz

1 Which router is best used as a central site router 2611, 3640, or 1004 The 3640 router provides more power than the 2611 or 1004. Therefore, it is the best choice of the three for a central site router. 2 Which router best serves as a small office or home office (SOHO) router for telecommuters 7200, 700, or 7500 The 700 router is best suited for the role of a SOHO router. The 7200 and 7500 routers are suited for roles as core routers. 3 Which WAN technology is best suited for providing...

Answers to Chapter 4 Do I Know This Already Quiz

1 What pins are used for modem control Pins 6, 8, and 20 are used for modem control. 2 What is the standard for DCE DTE signaling The standard is EIA TIA 232. 3 In character mode using reverse Telnet, what is the command to connect to the first async port on a 2509 router that has a loopback interface of 192.168.1.1 4 What port range is reserved for accessing an individual port using binary mode The port range is 6000-6999. 5 If a four-port serial (A S) module is in the second slot on a 3640...

Answers to Chapter 4 QA Section

1 What pins are used for modem control Pins 6, 8, and 20 are used for modem control. 2 What is the standard for DCE DTE signaling The standard is EIA TIA 232. 3 If the user wants to terminate a call, what pin does the DTE device drop to signal the modem 4 What must be done to terminate a reverse Telnet session with an attached modem You must press Ctrl+Shift+6, press x, and then execute a disconnect. 5 In character mode using reverse Telnet, what is the command to connect to the first async...

Answers to Chapter 6 QA Section

1 List the two most common implementations of ISDN. The two most common implementations are BRI and PRI. 2 List the number of bearer channels for BRI, T1 PRI and El PRI. The numbers are BRI 2, T1 PRI 23, and E1 PRI 30. 3 What type of information is carried over the D channel Signaling (and sometimes data, depending on the implementation) is carried over the D channel. 4 List the specifications that define Layer 2 and Layer 3 of ISDN. The specifications are Layer 2 Q.921 and Layer 3 Q.931. 5...

Answers to Chapter 7 QA Section

1 What are the three permanent profiles for the 700 series router The profiles are LAN, standard, and internal. 2 Which one of the following statements is true a. Any protocol routed in the LAN must be routed in the user profile. b. Any protocol routed in the LAN cannot be routed in the user profile. c. Any protocol routed in the LAN must be bridged in the user profile. d. Any protocol routed in the LAN cannot be bridged in the internal profile. The answer is a. Any protocol routed in the LAN...

Answers to the Chapter 10 QA Section

1 Where on a router is queuing implemented Queuing should be implemented on low-speed WAN interfaces only. 2 When should queuing be considered a viable implementation Queuing should be considered a solution when the router experiences more than occasional congestion. If the existing traffic flow is having problems getting through the router on a regular basis, queuing should be considered. 3 Should a queuing strategy be implemented on all WAN interfaces No. Queuing should be implemented on...

Answers to the Chapter 11 Do I Know This Already Quiz

1 What are the benefits of NAT The benefits of NAT include conservation, overlap dysfunction, flexibility, and the elimination of renumbering. Addresses are conserved because real addresses are not needed for the private network. Overlap dysfunction occurs when two companies, which were using the same address space, merge. Renumbering occurs when a company changes ISPs and keeps the same internal address space. When this occurs, only the NAT device requires a change. 2 What are the...

Answers to the Chapter 8 QA Section

The Layer 2 is LAPB. 2 Name the Layer 3 of X.25. The Layer 3 is X.25. 3 In X.25, what are the two possible roles that a router can play The roles are DCE and DTE. 4 What is the function of a PAD in an X.25 network The PAD is a device that collects data from asynchronous terminals and outputs that data encapsulated inside of X.25 packets. 5 The addressing scheme in X.25 is known as what kind of address It is known as X.121 addressing. 6 List the parts of the...

Answers to the Chapter 9 Do I Know This Already Quiz

1 Is Frame Relay connection-oriented or connectionless Frame Relay is connection-oriented. Answers to the Chapter 9 Do I Know This Already Quiz 425 2 Frame Relay virtual circuits come in two flavors. What are those flavors Frame Relay virtual circuits can be PVC or SVC. 3 Frame Relay virtual circuits are logically defined by a DLCI. What is the range of valid DLCIs Valid DLCIs fall in the range of 16-1007. 4 The Frame Relay star topology is also known as what It is also known as hub and spoke....

Answers to the Chapter 9 QA Section

1 Is Frame Relay connection-oriented or connectionless Frame Relay is connection-oriented. 2 Frame Relay virtual circuits come in two flavors. What are those flavors Frame Relay virtual circuits can be PVC or SVC. 3 Frame Relay virtual circuits are logically defined by a DLCI. What is the range of valid DLCIs Valid DLCIs fall in the range of 16-1007. 4 The Frame Relay star topology is also known as what It is also known as hub and spoke 5 In a 40-route Frame Relay network running in a full mesh...

AS5X00 Router Series

This family of routers is an Access Server line (hence the AS in the name). The available models in the line are the AS5200, the AS5300, and the AS5800. The series also includes a very highend model known as the AccessPath. It consists of a number of AS5300s operating together in a single integrated rack with a Catalyst switch collocated. The AS5X00 family of devices can provide carrier class service scalability as well as multiprotocol routing services. These devices are usually deployed in an...

Basic Rate Interface

BRI is the most typical ISDN connection and is a native ISDN interface on a router. The basic rate connection consists of two bearer (B) channels and a single (D) channel. When both B channels are active, the aggregate bandwidth becomes 128,000 bps. You can purchase ISDN service with two, one, or zero B channels. Typical deployments use two B channels. Implementations of one B channel provide cost reduction, and zero B channel implementations enable another technology (such as X.25) to be run...

BRI and PRI Basics

ISDN interfaces can be either PRI or BRI. A PRI differs from a BRI mainly due to the number of channels it offers. ISDN channels are usually divided into two different types B and D The bearer channel The B channel is the facility that carries the data. Each B channel has a maximum throughput of 64 kbps. B channels can carry encoded pulse code modulation (PCM) digital voice, video, or data. B channels are used mainly for circuit-switched data communications such as High-Level Data Link Control...

Central Site Installations

If the installation is taking place in a central or corporate headquarters site, room for growth should be a strong consideration. Room for growth is important because remote or branch sites can be added or deleted over time and the hardware platform should be flexible so that a forklift upgrade is not needed every time a change in corporate strategy occurs. Decisions for the central office should include evaluation of speeds and feeds. The speeds should be sufficient to aggregate the...

Scaling IP Addresses with NAT 331

Do I Know This Already Quiz 332 Simple Dynamic NAT Configuration 344 NAT TCP Load Distribution Configuration 349 Foundation Summary 355 Q& A 356 Scenarios 361 Scenario 11-1 361 Scenario 11-2 361 Scenario 11-3 362 Scenario Answers 363 Scenario 11-1 Answers 363 Scenario 11-2 Answers 364 Scenario 11-3 Answers 364

Using AAA to Scale Access Control in an Expanding Network 367

Do I Know This Already Quiz 368 AAA Overview 372 Authentication 372 Authorization 373 Accounting 373 AAA Configuration 374 Enabling AAA 374 AAA Authentication 375 AAA Authentication Login 376 AAA Authentication Enable 377 AAA Authentication ARAP 378 AAA Authentication PPP 379 AAA Authentication NASI 380 Scenario 12-1 393 Scenario Answers 394 Scenario 12-1 Answers 394 Appendix A Answers to the Do I Know This Already Quizzes and Q& A Sections 397

Assembling and Cabling the WAN Components

Do I Know This Already Quiz 44 Choosing WAN Equipment 48 Central Site Router Selection 48 3600 Router Series 49 4000 Router Series 50 AS5X00 Router Series 50 7200 Router Series 51 Branch Office Router Selection 51 1600 Router Series 52 1700 Router Series 52 2500 Router Series 52 2600 Router Series 52 Small Office Home Office (SOHO) Router Selection 53 700 Router Series 53 800 Router Series 53 1000 Router Series 53 Assembling and Cabling the Equipment 54 Available Connections 54 3600 Router LEDs...

Configuring Asynchronous Connections with Modems

Do I Know This Already Quiz 68 Modem Signaling 72 Data Transfer 73 Data Flow Control 73 Modem Control 73 DTE Call Termination 74 DCE Call Termination 74 Modem Configuration Using Reverse Telnet 74 Basic Asynchronous Configuration 78 Logical Considerations on the Router 79 Physical Considerations on the Router 80 Configuration of the Attached Modem 82 Modem Autoconfiguration and the Modem Capabilities Database 82 Chat Scripts to Control Modem Connections 84 Reasons for Using a Chat Script 85...

Using ISDN and DDR Technologies 125

Do I Know This Already Quiz 126 Basic Rate Interface 131 BRI Protocols 133 ISDN Layer 1 133 ISDN Layer 2 135 ISDN Layer 3 138 ISDN Call Setup 139 ISDN Call Release 141 Step 1 Setting the ISDN Switch Type 142 Step 2 Specifying Interesting Traffic 143 Specifying Interesting Traffic with Access Lists 144 Step 3 Specifying Static Routes 145 Step 4 Defining the Interface Encapsulation and ISDN Addressing Parameters 146 Configuring ISDN Addressing 146 Step 5 Configuring Protocol Addressing 147 Step 6...

Compression Issues

Specific issues arise during specific network implementations. In selecting the algorithm that will be utilized for a particular deployment, the following should be considered Modem compression Some modems implement compression. Modems making use of MNP5 and V.42bis are not compatible. Although each offers 2 and 4 times compression, they cannot communicate with each other. If you use modem compression, make sure that the modems at both ends of the connection are using a common protocol. If...

Compression Overview

Various types of compression algorithms are in use in the world today. Many are well conceived and utilized. Others, well, let's just say they're the opposite. For compression, a scope needs to be set ahead of time. There are compression methods for data, links, hard drives, and so on. Our discussion in this chapter focuses on compression across WAN links. Whether data is already compressed when WAN links begin to process it affects the router's capability to further compress that data. If data...

Configuring a Cisco 700 Series Router

The 700 series router was purchased by Cisco from Combinet in 1997. The purchase gave Cisco an ISDN product uniquely suited to the telecommuter and SOHO market. The 700 series provides single Basic Rate Interface (BRI) connectivity and an Ethernet interface for a LAN connection. The 700 series router is compatible with the full Cisco router product line however, it does not use the same command line structure for configuration. The command line of the 700 series router uses set as the main verb...

Configuring ISDN Addressing

ISDN addressing uses phone numbers that are exactly like the phone numbers utilized by millions of people day in and day out. These numbers are telco-designated and locally significant. They usually include an area code, a local exchange, and additional digits. To function, the router must understand what phone number to dial as well as when to dial it. How does it come to know this information The same way it knows everything else it knows the administrator tells it. The administrator uses...

Configuring PPP and Controlling Network Access

The CCNP Remote Access Exam requires you to have an in depth understanding of various WAN technologies. In this chapter the discussion focuses on Point-to-Point Protocol (PPP). The typical implementation of PPP has traditionally been in dial-up and or ISDN deployments. The growing need of corporations to include dial-up access to network resources for remote users has created a high demand for point-to-point technologies. Telecommuting personnel require access to network devices and information...

Configuring the Cisco 700 Series Router for IP Routing

There are three sections to configuring a Cisco 700 series router the system level, the LAN, and the user profile. The system profile contains that information that is generally found in the global configuration on an IOS router. The information includes the name of the router and the switch type. Additionally, the system level contains the encapsulation type, the authentication type, and the password used by the 700 series router when it connects to another device. This information is placed...

Contents at a Glance

Chapter 1 All About the Cisco Certified Network and Design Professional Certifications 3 Chapter 2 Cisco Remote Connection Products 19 Chapter 3 Assembling and Cabling WAN Components 43 Chapter 4 Configuring Asynchronous Connections with Modems 67 Chapter 5 Configuring PPP and Controlling Network Access 97 Chapter 6 Using ISDN and DDR to Enhance Remote Connectivity 125 Chapter 7 Configuring the Cisco 700 Series Router 193 Chapter 8 Establishing an X.25 Connection 221 Chapter 9 Establishing...

Custom Queuing

Custom queuing enables the sharing of available bandwidth evenly (or not) across all types of traffic. This technique allocates a percentage of bandwidth to each of the various traffic types. The difference between this approach and priority queuing is that the queues are processed in round-robin sequence (in essence, they are multiplexed). Therefore, it is possible that high-priority traffic would not be serviced quickly enough because although each type of traffic would get some bandwidth, no...

Data Transfer

The pins used for data transfer are pin 2, 3, and 7. The DTE device raises the voltage on the RTS when it has buffer space available to receive from the DCE device. Once a call is established and the DTE device sees the DCE raise the voltage on the CTS, the DTE device transmits data on pin 2. Conversely, the DTE device will raise the voltage on the RTS when it has buffer space available to receive from the DCE device. The need for the ground pin is such that a positive or negative voltage can...

DCE Call Termination

If a far-end modem drops the CD because the remote DTE has ended the transmission, the near-end modem must signal the near-end DTE that the transmission has been terminated. The modem must be programmed to understand and signal this termination. In other words, the modem must be told how to handle the loss of carrier detection. By default, most modems understand that this signal loss is an indication that the call is to be terminated. However, it is a configuration parameter that the modem must...

Debug dialer Command

There are many more commands and command outputs that are useful in troubleshooting the dial process in general. For instance, the debug dialer command is one of the best tools to use in figuring out what traffic is attempting to traverse the ISDN link. Example 6-21 shows the debug dialer command output. Example 6-21 debug dialer Command Output SYS-5-CONFIG_I Configured from console by console Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.12.1.2, timeout is 2 seconds BRI0...

Dedicated and Interactive PPP Sessions

Asynchronous interfaces on an access server can be configured to accept inbound calls from remote users. There are two modes that can be used in this situation, interactive and dedicated. In interactive mode, users who dial into the network are able to access the user mode prompt. The user must enter the command ppp connect to initiate the connection. If access to the router prompt is unacceptable, dedicated mode should be used. Dedicated mode forces the connection into a PPP session once the...

Dial Backup

In Example 6-25, notice the backup delay 5 60 command, which specifies that if there is a failure, the system should wait five seconds to bring up the backup link. Once the failure has passed, the system should wait 60 seconds to bring the backup link back down. Example 6-25 Dial Backup Example Configuration RouterA(config) isdn switch-type basic-5ess RouterA(config-if) ip address 10.14.1.1 255.255.255.0 RouterA(config-if) encapsulation hdlc RouterA(config-if) backup interface BRI0...

Do I Know This Already Quiz

The purpose of the Do I Know This Already quiz is to help you decide what parts of this chapter to use. If you already intend to read the entire chapter, you do not necessarily need to answer these questions now. The twelve-question quiz helps you determine how to spend your limited study time. The quiz is sectioned into smaller, two-question quizlets, each of which corresponds to the six major topic headings in the chapter. Use the scoresheet in Table 4-1 to record your scores. Table 4-1...

DTE Call Termination

When the DTE is ready to terminate the connection because the user has completed the call and signaled the PC to go back on-hook, the DTR is dropped. For this to happen, the modem must be configured to interpret the loss of the DTR as the end of a conversation. When the DTE drops the DTR, the modem is alerted that the carrier is no longer needed. This configuration is done when the modem is first installed. This can be manually done for each call, or it can be scripted in a chat script that is...

Dynamic NAT Configuration

The simplest form of configuration is a one-to-one translation in which the IP address of the Inside Local address in the network header is replaced by an Inside Global address. The replacement can be done statically or dynamically. Example 11-1 shows a simple NAT translation with the assignments done dynamically. The following conditions dictate the use of NAT translation Only on interfaces that are declared inside or outside can packets be translated. Only traffic from an outside to an inside...

E1 Line Code

E1 deployments can implement AMI however, the issues with AMI and data transmission still hold true data transmissions are limited to 56 kbps. To remedy this, high-density bit, level 3 (HDB3) was created. It operates similarly to B8ZS, but in a slightly more efficient manner. If a long string of 0s is detected, a number of them are changed to 1s for the duration of their trip across the provider network. They are then changed back to their original values at the remote CSU DSU. Obviously, T1 E1...

Establishing an X25 Connection

The CCNP Remote Access Exam requires you to be familiar with the implementation options associated with X.25. You must understand the basic deployment of X.25 as well as the optional configuration parameters. X.25 is similar in some respects to ISDN. The basic functionality of the two is based on the same technology, and the Public Switched Telephone Network (PSTN) still provides the necessary switching facilities. X.25 is similar not only to ISDN for switched virtual circuits (SVCs) but also...

Feedback Information

At Cisco Press, our goal is to create in-depth technical books of the highest quality and value. Each book is crafted with care and precision, undergoing rigorous development that involves the unique expertise of members from the professional technical community. Readers' feedback is a natural continuation of this process. If you have any comments regarding how we could improve the quality of this book, or otherwise alter it to better suit your needs, you can contact us through email at...

Fifo

FIFO is the most basic of strategies. In essence, it is the first-come, first-served approach to data forwarding. In FIFO, packets are transmitted in the order in which they are received. Until recently, FIFO was the default queuing strategy for all interfaces on a router. However, should it become necessary for the traffic to be reordered in any way, another strategy must be invoked because FIFO gives no regard to one type of traffic over another. It simply dispatches data as it receives it....

Foundation Summary

Overall, this chapter dealt with physical connectivity for the router. Most cables are interface-specific in that they can be attached at only one place on the router. That is not always the case, however. For example, Category 5 UTP cable can be used with Ethernet, T1 E1 WIC, and ISDN interfaces. You should take the time to ensure that the correct cable is attached in the appropriate place. A straight-through Ethernet cable does not work in a T1 E1 WIC connection. The pinouts are dissimilar....

Foundation Topics

The discussions in this chapter revolve around a fictitious, albeit typical, network topology. Figure 3-2 depicts that topology. Figure 3-2 Network Topology for Chapter Discussion Figure 3-2 Network Topology for Chapter Discussion Figure 3-2 depicts a number of technologies in the network. These technologies (ISDN, Frame Relay, X.25, and so on) are discussed in this book at various times and are not discussed in this chapter. You must understand the concepts and components involved in properly...

Foundation Topics Cisco 700 Series Router Key Features and Functions

The key features of a 700 router are Internet access for multiple users over one ISDN line The Cisco 700 series router enables multiple PCs to access the Internet simultaneously. This keeps users from having to share a single PC with an Internet connection or rely on server-based hardware and software. A single Cisco 700 series router can make everyone in the office more productive. Affordable Internet connections for SOHOs With the Cisco 700 series, there's no need to install a separate ISDN...

Foundation Topics Modem Signaling

This chapter covers the signaling of the modem and the configurations for a Remote Access Server (RAS) connection. The successful CCNP or CCDP candidate should be able to describe the signaling and pins used by the cabling and not just the syntax that is required for the connection. The signaling is just as important because it provides the basis for the physical-layer troubleshooting that can be needed to establish a connection. Asynchronous data communications technology occurs when an end...

Foundation Topics Understanding Frame Relay

Frame Relay is a connection-oriented, Layer 2 networking technology. It operates at speeds from 56 kpbs to 45 Mbps. It is very flexible and offers a wide array of deployment options. Frame Relay operates by statistically multiplexing multiple data streams over a single physical link. Each data stream is known as a virtual circuit (VC). Frame Relay VCs come in two flavors, permanent and switched. Permanent Virtual Circuits (PVCs) are, just as the name implies, permanent, nailed up circuits. They...

Frame Relay Configuration

The basic configuration of Frame Relay is quite simple. In many cases, the configuration can be as simple as setting the encapsulation and putting an IP address on the interface. This enables inverse-ARP to dynamically configure the DLCI and discover neighboring routers across the cloud. However, configurations are rarely that simple. Although basic functionality can be achieved in this manner, more complex procedures are necessary for hub and spoke subinterface configurations dealing with...

Frame Relay Connection Controlling Traffic Flow

The CCNP Remote Access exam requires you to have an in depth understanding of various WAN technologies. This chapter discusses the basics of Frame Relay as well as how to tweak it to maximize traffic control and throughput. Although Frame Relay is not a new technology by any means, it is still widely implemented around the world. Even with the advent of newer (and faster) broadband technologies, Frame Relay continues to remain popular in the workplace. Frame Relay is a high-performance WAN...

Frame Relay LMI

Local Management Interface (LMI) is the means by which Frame Relay edge devices maintain keepalive messages. The Frame Relay switch is responsible for maintaining the status of the CPE device(s) to which it is attached. LMI is the communication by which the switch monitors status. LMI implements a keepalive mechanism that verifies connectivity between DCE and DTE and the fact that data can flow. A LMI multicast capability, in conjunction with an LMI multicast addressing mechanism, enables...

Frame Relay Topologies

Frame Relay supports connectivity of remote sites through one of three topological strategies. Each has its own advantages and disadvantages, as pointed out in the following list Hub and spoke Also known as the star topology, this is the dominant method of deploying Frame Relay. It consists of a single central site acting as a connection point for all remote offices. Routing between two satellite offices is accomplished through the central site. Routing through the central site tends to be the...

Frame Relay Traffic Parameters

To properly understand the concepts of traffic shaping, it is important to have a firm grasp of the various traffic parameters in the Frame Relay Network. In particular, you should know that some (such as CIR and Be (Excessive Burst)) are commonly used, but misunderstood. Table 9-2 details the traffic parameters. Table 9-2 Frame Relay Traffic Parameters The average rate you want to transmit. This is generally not the same as the CIR provided by the telco. This is the amount you want to send in...

Frame Relay Traffic Shaping Configuration

Frame Relay traffic shaping is accomplished through the creation of a map class. This map class can be associated with one or more PVCs. The map class defines the traffic parameters for any circuits to which it is applied. The command structure for defining the map class is as follows RouterA(config) map-class frame-relay name The name parameter is an arbitrary value. This is the parameter that is used to tie the map class to one or more PVCs. Once the map-class command has been entered, the...

Hardware Selection

When the research is done and the location is selected, the last step is to select a router that meets the specifications created. Cisco is continually updating the product line for all types of WAN scenarios. The best way to stay current with the offerings available for RAS solutions is at the Cisco web site at www.cisco.com. The products in the following section represent some of the current offerings for Remote Access environments. The successful CCNP or CCDP candidate should be aware of the...

How to Best Use This Chapter

By taking the following steps, you can make better use of your study time Keep your notes and answers for all your work with this book in one place for easy reference. Take the Do I Know This Already quiz and write down your answers. Studies show retention is significantly increased through writing facts and concepts down, even if you never look at the information again. Use the diagram in Figure 2-1 to guide you to the next step.

How to Use This Book to Pass the Exam

There are five sections in each chapter a short pre-assessment quiz, the main topics of the chapter, a summary of the key points of the chapter, a test to ensure that you have mastered the topics in the chapter, and finally (when applicable), a scenario section with scenario-related questions and exercises. Each chapter begins with a quiz, which is broken into quizlets. If you get a high score on these quizlets, you might want to review the Foundation Summary section at the end of the chapter...

Implementing Basic DDR

Dial-on-demand routing (DDR) is a feature available on ISDN-capable Cisco routers. It was created to enable users to save money on usage-based ISDN. Use-based ISDN occurs when charges are assessed for every minute of ISDN circuit connect time. Obviously, in a charge-by-the-minute scenario, the connection should be down during no or low-volume traffic times. DDR provides that capability and offers a wide array of commands and configuration variations. Many of those configuration options are...

ISDN and Telephony

The 700 series router provides dial tone for the telephone service on plain old telephone service (POTS) RJ-11 interfaces. On the earlier 700 series models (750 760), the model number defined the ISDN interface type. The 700 series models that ended in an even number provided the built-in network termination 1 (NT1) interface for ISDN. The models that ended in an odd number provided an S T interface, for which the customer had to supply the NT1 device if it was needed. In the United States, the...

ISDN Call Release

Any party in the network can release the call for whatever reason. Whether the release of the call is intentional or accidental (that is, due to some type of failure in the network), the call is torn down completely. When either the calling or called party is ready to disconnect a call, that party issues a disconnect (DISC) message. The disconnect is not negotiable. If necessary, the call can be re-established, but once a disconnect is issued, the call comes down. When a DISC is issued, it is...

ISDN Layer

The Layer 2 processes of ISDN are defined in the ITU specifications Q.920 and Q.921. Q.921 defines the actual communication format. Obviously, Layer 2 communication does not take place unless Layer 1 is properly installed and functioning. Q.921 institutes an addressing scheme similar to many other networking technologies. Just as in LAN implementations, ISDN Layer 2 addressing is meant to provide physical addressing on the network. Because multiple logical devices can exist in a single physical...

Issues When Connecting Multiple Sites Through a Single Router Interface

When a single physical interface is utilized on a central router to connect multiple remote sites, routing problems arise. These problems are caused by split horizon. Split horizon is a rule in routing protocol operation that is designed to eliminate routing loops by not allowing routing updates to be sent out of the interfaces through which they were received. Consider the situation in which one serial interface serves multiple remote sites. In this scenario, split horizon effectively shuts...

Know This Already Quiz

The purpose of the Do I Know This Already quiz is to help you decide which parts of this chapter to use. If you already intend to read the entire chapter, you do not necessarily need to answer these questions now. The six-question quiz helps you determine how to spend your limited study time. The quiz is sectioned into smaller quizlets, each of which corresponds to the four major topic headings in the chapter. Use the scoresheet in Table 2-1 to record your scores. Table 2-1 Scoresheet for...

Link Compression

Link compression (also known as per-interface compression) is the compression of the entire transported entity. In other words, it compresses the header and the payload. Link compression is not dependent on any particular protocol function. Cisco supports two algorithms on its router chassis to compress traffic STAC and Predictor. For HDLC links, STAC is the only available choice. For data transmission over point-to-point dedicated connections, use link compression. In link compression, the...

Logical Considerations on the Router

Logical considerations are configured on the interface of the router. These include the network-layer addressing, the encapsulation method, the authentication, and so on. The configuration in Example 4-5 is for a serial interface that is used to receive an inbound call. Example 4-5 Router Configuration for Serial Interface Receiving Inbound Calls interface Serial2 physical-layer async ip unnumbered EthernetO ip tcp header-compression passive encapsulation ppp bandwidth 38 async mode interactive...

Modem Autoconfiguration and the Modem Capabilities Database

Modem autoconfiguration is a Cisco IOS software feature that enables the router to issue the modem configuration commands, which frees the administrator from creating and maintaining scripts for each modem. The general syntax for modem autoconfiguration is as follows modem autoconfigure discovery type modemcap-entry-name The two command options for the modem autoconfigure command are as follows type This option configures modems without using modem commands, or so it is implied. The type...

Multilink PPP

Multilink PPP is a specification that enables the bandwidth aggregation of multiple B channels into one logical pipe. Its mission is comparable to that of Cisco's BOD. More specifically, the Multilink PPP feature provides load-balancing functionality over multiple wide area network (WAN) links, while providing multivendor interoperability, packet fragmentation and proper sequencing, and load calculation on both inbound and outbound traffic. Cisco's implementation of Multilink PPP supports the...

NAT Definitions

The addresses used for NAT translation can be summed up in four categories Inside Local IP addresses that are unique to the host inside the network, but not globally significant. They are generally allocated from RFC 1918 or randomly picked. Inside Global IP addresses that are assigned by the IANA or service provider. They are legitimate in the global address space or Internet. The Inside Local addresses are translated to the Inside Global address for Internet use. Outside Local IP addresses of...

NAT Overloading Configuration

To convert the configuration for simple NAT translation to overload, the administrator must use the overload argument. Overloading an Inside Global address uses the same syntax as the simple NAT translation, but with the extra argument, the router knows to track the port numbers for the translation table. The configuration in Example 11-3 extends simple NAT translation to an overload implementation. Example 11-3 NAT Overload Implementation define what addresses are to be converted access-list 1...

One Final Word of Advice

The Foundation Summary section and your notes are your crib note knowledge of Remote Access. These pieces of paper are valuable when you are studying for the CCIE or Cisco recertification exam. You should take the time to organize them so that they become part of your paper long term memory. Reviewing information that you actually wrote in your own handwriting is the easiest data to put back into your brain RAM. Gaining a certification but losing the knowledge is of no value. For most people,...

Overlapping Networks

Another use of NAT occurs when two networks are overlapped, or using the same numbering scheme. If they are merged, the IP address scheme fails because of the overlap. This NAT function is not something that should be designed into a network. NAT overlap aids the administrator when a merger occurs. The two entities, without the renumbering of each end station, can be consolidated. In this fashion, the administrator can focus on putting a renumbering plan in place. Overlapping networks can occur...

Overloading

Overloading uses the source port to further distinguish which sending station is transmitting. In this fashion, a single legitimate IP address can be used for many senders. The source port is a number greater than 1024 and is a software addressable port at the transport layer. The first 1024 port numbers are well-known ports, which are assigned by RFC 1400. The terms socket and port are often used interchangeably. This is incorrect. A socket is the IPaddress Portnumber pair that is unique to an...

Payload Compression

Payload compression is exactly what its name implies. Also known as per-VC compression, payload compression compresses only the data portion of the transmission. All headers are left intact. It cannot be assumed that customer WAN links are all dedicated point-to-point connections. To that end, payload compression might need to be implemented if compression is needed on a WAN link. WAN technologies such as Frame Relay, ATM, X.25, and SMDS require that the header information be untouched so that...

PPP Authentication

The topic of authentication has been touched on throughout this chapter. At this point, it is finally time to get down to specifics. PPP authentication offers two options PAP and CHAP. These two protocols offer differing degrees of protection. Both protocols require the definition of usernames and accompanying passwords. This can be done on the router itself or on a TACACS or RADIUS authentication server. The examples we deal with in this book are those in which the router itself is configured...

PPP Components

PPP can operate across any DTE DCE interface. The only absolute requirement imposed by PPP is the provision of a duplex circuit, either dedicated or switched, that can operate in either an asynchronous or synchronous bit-serial mode, transparent to PPP link layer frames. Other than those imposed by the particular DTE DCE interface in use, PPP does not impose any restrictions regarding transmission rates. In just about every type of WAN technology in internetworking, a layered model is shown to...

PPP Troubleshooting

Troubleshooting PPP is similar to troubleshooting many other WAN technologies. However, there is a key difference The implementation of authentication adds another item to the list of things that can go wrong. This section details some of the commands useful in dealing with PPP issues. The first step in troubleshooting PPP connections is to remove authentication of any kind from the configuration. If the service functions properly at that point, it's time to rethink your authentication...

PRI Configuration

The configuration of the PRI service is quite simple. Although the command variations and options are very similar to that of its BRI counterpart, a PRI configuration has additional requirements. To meet the needs of the PRI provisioning, the T1 or E1 (whichever is appropriate) must be configured to match telco requirements of framing and line code, as discussed in the preceding sections of this chapter. The T1 E1 controller is actually an internal CSU DSU. It must be told which timeslots are...

PRI Incoming Analog Calls on Digital Modems

Up to this point, the discussion has focused on data calls. In other words, the topics have centered on B channel to B channel calls. In remote access deployments, the end user dials into an access server. The incoming lines that provide connectivity from end user to the access server are PRI implementations. These PRI lines are completely digital facilities. Figure 6-16 illustrates the typical deployment of an access server installation. Figure 6-16 Network Access Server Deployment When an end...

Primary Rate Interface

PRI implementations are based on T1 E1 technologies. Although PRI is still ISDN, it is treated differently in regard to framing and signaling. Like BRI, PRI has only one connection to the ISDN network, and the switch type must be specified for the configuration to function. An ISDN PRI T1 implementation has 23 B channels and a D channel. As with BRI, each of the B channels has 64-kbps bandwidth available. The D channel, however, is also a 64-kbps channel (unlike BRI). In traditional T1...

Priority Queuing

When absolute control over the throughput is necessary, priority queuing can be utilized. Priority queuing gives the network administrator granular control that reduces network delay for high-priority traffic. Variations of priority queuing have been in use for a number of years in differing vendor implementations. Cisco's implementation of priority queuing utilizes four queues high, medium, normal, and low. For traffic placed in individual queues, the output strategy is FIFO. The traffic...

Product Families Capabilities and Limitations

The Cisco 700 series family of routers supports IP and IPX routing over ISDN. Routers from this family have no scalability for adding ports and were designed for ROs and SOHOs. A 700 series router is an inexpensive ISDN access device. Figure 2-2 illustrates a Cisco 700 series router. The Cisco 800 series family of routers is the lowest priced entry-level router that runs the IOS software. Because the base operating system for the 800 series router is the same as for the higher end router...

Profile Configuration Commands for the Cisco 700 Series Routers

Profile commands are used to establish the basics of the 700 series router configuration. The commands can be categorized for use in the three basic profiles used. Table 7-2 summarizes the commands used for the three basic profiles. This command declares the switch type for the 700 series router. Valid choices would be DMS100, 5ESS, NI1, and so on. Because the 700 series router only supports a single BRI interface, there is no need for further definition of the switch type. This command...

Profile Management Commands for the Cisco 700 Series Routers

Table 7-3 summarizes the commands used for managing the Cisco 700 series router profiles. set user This command initially creates the profile (or subdirectory) for the connection called user. Selecting the name user for a connection is similar to naming a router router. Generally, the name of the connection is something that is meaningful to the connection. upload This command writes the configuration to the monitor screen. The configuration is presented on the screen without page breaks. It is...

Profile Use Guidelines

Much ado is made about routing in the profiles. Simply stated, an unknown call is not handled with the route engine, and the standard profile does not support routing. On the other hand, a known call, or one with an associated profile, is passed to the internal profile if IP or IPX routing has been declared for the profile and then sent to the route engine for processing to the LAN. The following guidelines should be known by the successful CCNP candidate Functions LAN and internal profiles...

Queuing Overview

The misconception that queuing is a necessary part of any router configuration is a topic that needs to be dealt with straight away. As mentioned earlier, implementation of any queuing strategy results in higher delay in the network. This happens because of a higher per packet processor requirement. In other words, each traffic type must be sorted out and dealt with according to the defined parameters of the queue. This is the trade-off for assuring that your critical traffic passes through the...

Recommended Training Path for CCNP and CCDP

The recommended training path for the Cisco professional level certifications is, of course, the Building Scalable Cisco Networks (BSCN) The BSCN class covers the advanced routing protocols and the scaling issues involved with a large routed network with multiple protocols. Building Cisco Multilayer Switched Networks (BCMSN) The BCMSN class covers the switch infrastructure and the configuration in a large network environment. Building Cisco Remote Access Networks (BCRAN) The BCRAN class covers...

Resolving Split Horizon Problems

Theoretically, almost any number of subinterfaces can be placed on a single major interface. The limit lies in the number of Interface Descriptor Blocks (IDBs) available to the router. This number varies depending on the router series and Cisco IOS Software release. A logical subinterface should be treated almost the same as a physical interface. It can be configured for multiple protocols, shut down, or anything else common on other interfaces with one notable exception you cannot set...

Router LEDs

The 1600 router is a mission-specific router. It's capable of sustaining one WIC, one BRI, and one LAN interface. LEDs on the router consist of those appropriate to each type of interface as well as two system LEDs. Refer to Figure 3-5 for the 1600 LEDs. The system LEDs are PWR and OK. They are fairly self-explanatory. The PWR LED should be green if the router is powered on. The OK LED should be green if the router has passed the POST. The OK LED flashes during the router boot sequence. The BRI...

Router Line Numbering

The line numbers on a router are obtained in a methodical manner. The console port is line 0. Each asynchronous (TTY) port is then numbered 1 through the number of TTY ports on the router. The auxiliary port is given the line number LAST TTY + 1, and the virtual terminal (vty) ports are numbered starting at LAST TTY + 2. Example 4-1 has the show line output for a Cisco 2511 router, which has eight asynchronous ports available. Notice that the AUX port is labeled in line 17 and the vty ports are...

Router Selection Criteria for Remote Access Purposes

The selection of a hardware product for Remote Access usage is an art form to some extent, and the biggest router possible is not always the best router. For instance, information gathered about the site is also critical. Generally speaking, the information you must consider to select the appropriate piece of network hardware consists of the following Availability Ask yourself if you can get the service in your area, and what are the geographic restrictions to this technology, who are service...

Router Series

The 3600 series is a versatile family of routers for variations of supported technologies, it is hard to beat. It is a multifunctional platform that enables routing of data, voice, video, and dial access capabilities in a single chassis. The 3600 series offers three chassis variants 3620, 3640, and the new 3660. The 3620 has two module slots, the 3640 has four module slots, and the 3660 has six module slots. Each module slot can contain MICA modems for dial-in access, voice network modules for...

Scenario 1 You Have Taken the Bcran Course

Because you have taken other Cisco exams and have taken the BCRAN course, you know what you are up against. The Remote Access exam is like all the others. The questions are Sylvanish and the answers are sometimes confusing if you read too much into them. The best approach with this book is to take each chapter Do I Know This Already quiz and focus on the parts that draw a blank. It is best not to jump to the final exam until you have given yourself a chance to review the entire book. You should...

Scenario 101 Answers

1 Example 10-13 details the Fort Worth router configuration for WFQ. Example 10-13 Fort Worth Router Fair Queuing Configuration 2 Example 10-14 details the Atlanta router configuration for WFQ. Example 10-14 Atlanta Router Fair Queuing Configuration 3 Example 10-15 details the San Mateo router configuration for WFQ queuing. Example 10-15 San Mateo Router Fair Queuing Configuration

Scenario 102 Answers

1 To meet the requirements of this scenario, a custom queuing implementation is necessary. 2 Example 10-16 details the configuration necessary to fulfill the requirements of this task. The default byte-count threshold is 1500. The default queue limit is 20 records. The task calls for 5 times the service thresholds. Therefore, 7500 bytes (1500 x 5) and 100 records (20 x 5) are necessary to meet the requirements. The appropriate protocol and ports have been added to the configuration to meet the...

Scenario 103 Answers

1 To meet the needs specified by this scenario, a priority queuing implementation is necessary. 2 Example 10-17 details the configuration for this task. DNS, FTP, Telnet, TFTP, and HTTP are placed into the high-priority queue. 3 Example 10-17 details the configuration for this task. The remaining IP traffic is placed into the medium queue to meet the requirement that it be a high priority, but not as high as the protocols mentioned in Task 2. 4 Example 10-17 details the configuration for this...

Scenario 113 Answers

1 To provide immediate connectivity, you can use the overlap feature in NAT. This would enable the ABC and XYZ companies to coexist during a transition. 2 The following NAT configuration could be used, given a selection of 192.168.1.0 24 as the internal addresses used ip nat pool XYZ-in 192.168.1.2 192.168.1.254 prefix-length 24 ip nat pool ABC-out 192.168.2.2 192.168.2.254 prefix-length 24 ip nat outside source list 1 pool XYZ-in ip nat inside source list 1 pool ABC-out Ideclare the static...

Scenario 121 Answers

1 The router configuration given an AAA address of 123.123.123.123 using a password of AAAsecret would be as follows Routen(config) radius-server host 123.123.123.123 Router(config) radius-server key AAAsecret Routen(config) aaa authentication login admins radius local Routen(config) aaa authentication login default radius Routen(config) aaa authentication ppp default radius Router(config) aaa accounting command 15 wait-start radius Router(config-line) aaa authentication admins...

Scenario 2 You Have NOT Taken the Bcran Course

Because you have taken other Cisco exams, you know what you are up against from the perspective of the test experience. The Remote Access exam is like the others. The questions are Sylvanish, and the answers are sometimes confusing if you read too much into them. The best approach with this book, because you have not taken the class, is to take each chapter's Do I Know This Already quiz to determine what to look for as you read the chapter. Once you have completed a chapter, take the...