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...

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...

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...

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

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...

Configuring a Cisco 700 Series Router 193

How to Best Use This Chapter 193 Do I Know This Already Quiz 194 Foundation Topics 197 Cisco 700 Series Router Key Features and Functions 197 Networking 197 Routing and WAN 198 ISDN and Telephony 198 Cisco 700 Series Router Profiles 198 LAN Profile 199 Standard Profile 199 Internal Profile 199 System Profile 199 Profile Use Guidelines 199 Configuring the Cisco 700 Series Router for IP Routing 200 Profile Configuration Commands for the Cisco 700 Series Routers 203 Profile Management Commands for...

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 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...

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...

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...

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

ISDN refers to a set of digital services that has been available to end users for a number of years. It involves the digitizing of the telephone network so that carriers can provide end users with multiple services from a single end-user interface over existing telephone wiring. ISDN is an effort to standardize subscriber services, user network interfaces, and network and internetwork capabilities. The goal of standardizing subscriber services is to give some level of international...

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...

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 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...

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...

Physical Considerations on the Router

Physical characteristics are configured in line mode. These include the speed, the direction of the call, modem setup, and so on. Example 4-6 shows a configuration used to connect to a USR Sportster modem on physical line 2. Example 4-6 Router Configuration Connecting USR Sportster Modem on Physical Line 2 line 2 autoselect during-login autoselect ppp login local modem InOut modem autoconfigure type usr_sportster The login local command is the same for this line as it is for the console and AUX...

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...

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 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 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 routers in this series are established models. This router family makes use of Network Processing Modules (NPM) to implement different technologies. These individual cards can be mixed and matched to some degree for various technologies. LAN and WAN NPMs can be installed simultaneously at varying line speeds and encapsulations. Although this series is somewhat versatile, any changing of components requires the removal of the entire motherboard tray. Care...

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 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 22 Answers

1 ISDN would be a good choice because of the higher speed. You might consider making sure that the service is divergent into your branch office so that if the frame fails due to a back-hoe attack, the ISDN line has a chance of being uninterrupted. 2 Access control is a major issue. If the primary link fails, the backup link should block all noncritical traffic such as HTTP so that the mission critical information is not lost. It is assumed that the reason for the T1 is that the bandwidth is...

Scenario 31 Answers

1 For the growing central site, with 100+ users, it can be necessary to implement a 7200 router or higher. A 3640 could certainly handle the job. However, care must be taken in regards to future growth. If the site has few or no plans for growth in the near future, the 3640 is a good choice. The branch office site with only 10 users could function with a 1700, 2600, or similar router. The SOHO site with a single user will likely use ISDN for connectivity and a 1004 or 700 router. 2 For the...

Scenario 53 Answers

1 The symptom listed here is consistent with authentication failure. Show dialer or debug ppp authentication assists in troubleshooting the condition. 2 A callback failure of this sort can sometimes be attributed to busy B channels. If a callback request comes in and authentication is successful, the server disconnects the call. If this is the last available B channel, and a new call comes in, the new call takes the available B channel and callback cannot occur. This chapter covers the...

Scenario

In Figure 6-18, the Raleigh and Atlanta routers are dialing into the San Francisco router using DDR configurations. Example 6-33 details the configuration of the Raleigh router and Example 6-34 shows the Atlanta router configuration. Examine the figure and the configurations and utilize them in answering the questions that follow. Dialer 2 (BRI 0, 1, 2) 10.1.210.1 24 Dialer 2 (BRI 0, 1, 2) 10.1.210.1 24 isdn switch-type basic-5ess interface ethernet 0 ip address 10.25.2.2 255.255.255.0...

Scenario 81 Answers

1 Because the x25 pvc command is not specified and the x25 ltc and x25 htc parameters are specified, this is a SVC implementation. 2 Yes, there will be problems. The Dallas router has mapped its own IP address to the next hop X.121 address and the X.25 SVC ranges do not match. The SVC ranges must be identical on both sides. 3 Examples 8-8 and 8-9 correct issues with the existing configurations in Examples 8-6 and 8-7 Example 8-8 Corrected Dallas Configuration for Scenario 8-1 3 Examples 8-8 and...

Scenario 92 Answers

1 Some (not all) possible show commands include show frame-relay pvc show frame-relay map show frame-relay lmi show interfaces 2 Some (not all) possible debug commands include debug frame-relay lmi debug frame-relay packet debug frame-relay events 3 If LMI is not traversing the link between the router and the switch, check the LMI type configured on the router. If the LMI type is correct (that is, it's what the telco told you to use), a call to the telco can be in order. It's possible that your...

Scenario 93 Answers

1 The configuration for Router A is as follows RouterA(config) map-class frame-relay emma cir 128000 RouterA(config-map-class) frame-relay bc 16000 RouterA(config-map-class) frame-relay be 0 RouterA(config-map-class) frame-relay mincir 64000 RouterA(config) map-class frame-relay amanda RouterA(config-map-class) frame-relay cir 64000 RouterA(config-map-class) frame-relay bc 8000 RouterA(config-map-class) frame-relay be 0 RouterA(config-map-class) frame-relay mincir 32000 RouterA(config)...

Scenario Answers

The answers provided in this section are not necessarily the only possible correct answers. They merely represent one possibility for the scenario. The intention is to test your base knowledge and understanding of the concepts discussed in this chapter. Should your answers be different (as they likely will be), consider the differences. Are your answers in line with the concepts of the answers provided and explained here If not, go back and read the chapter again, focusing on the sections...

Service Profile Identifiers SPIDs

Another key part of the ISDN BRI Layer 2 is the SPID. SPIDs are used only in BRI implementations. PRI implementations do not require the use of SPIDs. The SPID specifies the services to which you are entitled from the switch and defines the feature set that you ordered when the ISDN service was provisioned. The SPID is a series of characters manually entered into the router's configuration to identify the router to the switch. This is different from the TEI discussed earlier. The TEI address is...

Show dialer Command

Executing the show dialer command displays active calls and status information. Example 6-19 shows sample output of calls in session. Example 6-19 show dialer Command Output Dial String Successes Failures Last called 0 incoming call(s) have been screened. Idle timer (120 secs), Fast idle timer (20 secs) Wait for carrier (30 secs), Re-enable (15 secs) Dial reason ip (s 10.12.1.1, d 10.12.1.2) Idle timer (120 secs), Fast idle timer (20 secs) Wait for carrier (30 secs), Re-enable (15 secs) Idle...

Simple NAT Translation

NAT translation (in its original form) replaced the source IP address with a publicly legitimate address. The replacement address came from a pool of addresses that were defined on the NAT device. These replacement addresses were, of course, publicly valid in the Internet address space. NAT is an application layer process that inserts the legitimate address into the packet header and maintains a table of translated addresses, as shown in Figure 11-3. Translation table 10.1.1.1 133.4.4.1 Source...

Snapshot Routing

Snapshot routing was developed to save bandwidth utilization across dialup interfaces. With snapshot routing, the routing table is placed in an update restricted (that is, frozen) state. This implementation of DDR utilizes a quiet period and an active period. The routing table is not updated during the quiet period, which is the amount of time that the routing table remains frozen. When the quiet period expires, a dialer interface initiates a call to a remote router. The active period is the...

SOHO Router Verification

These routers are generally quite small. Many of them are not much larger than the old Hayes and US Robotics modems of the 1980s. There is only so much that can be said about LEDs before the point is over emphasized. As in the two previous sections, this discussion focuses on a single router chassis, in this case, the 770 router. Figure 3-6 depicts the LEDs in this discussion. As you can see in the figure, there are a number of LEDs on this box. Table 3-2 analyzes the relevant LEDs, from left...

Specifying Interesting Traffic with Access Lists

Example 6-4 and 6-5 deal with a blanket statement enabling entire protocol suites. This type of implementation is not always the best, or preferred, method of defining interesting traffic. To define specific traffic types as interesting traffic, you should use access lists. Any type of access list can be implemented in defining interesting traffic. Rather than being associated with an interface, the access list is associated with the dialer-list. This access list discussion focuses on IP access...

Step 3 Specifying Static Routes

In the classic DDR model, dynamic routing protocol updates are not moving across the link, so it is important that static routes be used in place of dynamic updates. To provide bidirectional reachability between the two sites in the absence of routing protocol traffic, static routes should be configured at both the local and remote routers. As demonstrated in Example 6-6, any IP traffic that needs to cross the link has been defined as interesting and will trigger a call setup. Do not confuse...

Step 4 Configure Frame Relay Characteristics

You must define specific parameters for Frame Relay operation. The parameters include LMI and DLCI configuration. If you're using a release of IOS Software earlier than 11.2, you must specify the LMI type that is being implemented. The Frame Relay service provider, or telco, should provide the LMI information. For IOS Software Release 11.2 and later, you need not configure the LMI type. To disable LMI completely, use the no keepalive command to cease to transmit and receive LMI. However,...

Step 5 Configuring Protocol Addressing

Once the encapsulation has been decided upon, you must apply a protocol addressing scheme. You can configure DDR with any routable protocol. Each protocol that must pass across the link must have a configured address. For IP implementations, you must supply an IP address and subnet mask to the interface. The protocol addressing scheme should be decided upon well in advance of any deployment of any networking technology. In IPX implementations, you must apply an IPX network number to the BRI...

T

The set dhcp server command declares that the router be used as the DHCP server. The address pool and network mask are then declared. The syntax for the address pool is different from the syntax used to specify a pool in the IOS command set. The address (in this case, 10.1.1.2) is the first address in the pool. The second number (252) declares the number of addresses that are assigned internally for the DHCP pool. Hence, the pool in this case uses the IP addresses 10.1.1.2 through 10.1.1.253....

T1E1 Framing and Line Coding

Although it is ISDN, PRI uses T1 framing and line coding. These technologies are based on the same model, represented in a number of 64-kbps channels. The original use of digital facilities was the transport of voice traffic. Because analog technologies were not adequate for long distance transmission due to attenuation, another form of transmission digitizing was necessary. Digitizing the voice traffic for transmission enabled it to travel very long distances with no attenuation. Once the data...

Using Dialer Profiles

Dialer profiles first became a configuration option in Cisco IOS Release 11.2. The premise behind dialer profiles was to enable flexible design capabilities for deployment of custom profiles that meet users' dial access needs. This feature separates the logical function of DDR from the physical interface that places or receives the calls. Prior to dialer profiles, B channels had no choice but to take on the configuration options applied to the physical interface. In this type of deployment, all...

Using ISDN and DDR Technologies

The CCNP Remote Access Exam requires you to have an in depth understanding of various WAN technologies. In this chapter the discussion focuses on ISDN. ISDN is not a new technology by any means. However, it is still widely implemented around the world. Even with the advent of newer (and faster) broadband technologies, ISDN continues to grow in the workplace, albeit at a slower rate than what has been seen in the recent past. There are two specific implementation types discussed in this chapter...

Using the Cisco 700 Series Router as a DHCP Server and Relay Agent

The 700 series router is capable of being the DHCP server or functioning as a relay agent to a DHCP server running on another device. To perform the function of a relay agent, the router is configured as follows The use of the 700 series router as a relay agent is very similar to setting an IP helper-address on an IOS router pointing to a DHCP server. Using the set dhcp relay command passes only the DHCP request however, the IP helper-address can pass other broadcast packets if not configured...

Verification of NAT Translation

There are two commands to verify and troubleshoot the NAT configuration show ip nat translation and show ip nat statistics. The translation table is the same format for simple, overload, overlapped, and load distribution. The information provided is different depending upon the configuration. Example 11-6 shows the output for a simple translation. Example 11-6 Verifying NAT Translation Because this is a simple translation, only the information that is relevant is put into the table. The concept...

Verifying Frame Relay Configuration

The most useful method of verifying configurations is through the use of the show and debug commands. The examples in the following subsections show sample command output. Example 9-4 shows output from the show frame-relay pvc command. This command is useful for viewing the status of statically or dynamically defined PVCs. Example 9-4 show frame-relay pvc Command Output PVC Statistics for interface Serial0 0 (Frame Relay 39, last time pvc status changed 21 00 59 39, last time pvc status changed...

Warning and Disclaimer

This book is designed to provide information about the Cisco CCNP Remote Access Exam 640-505. Every effort has been made to make this book as complete and as accurate as possible, but no warranty or fitness is implied. The information is provided on an as is basis. The authors, Cisco Press, and Cisco Systems, Inc. shall have neither liability nor responsibility to any person or entity with respect to any loss or damages arising from the information contained in this book or from the use of the...

Weighted Fair Queuing

As mentioned, FIFO is often not ideal. Fortunately, WFQ enables Telnet and other interactive traffic to have priority over FTP and other large transfers, thus improving overall throughput. The FTP packets get through with relatively little delay, and Telnet users see improved response times. In WFQ, traffic is sorted by high- and low-volume conversations. The traffic in a session is kept within one conversation (session), and the records are handled FIFO within a particular conversation. The...