A

Figure 2-16 illustrates the process of upgrading Cisco IOS Software. Figure 2-16 Complete Cisco IOS Software Upgrade Process Figure 2-16 Complete Cisco IOS Software Upgrade Process Copy startup-config to running-config The boot process follows this basic litany 1 The router performs a power-on self-test (POST) to discover and verify the hardware. 2 The router loads and runs the bootstrap code from ROM. 3 The router finds the IOS or other software and loads it. 4 The router finds the...

A a

Example 8-15 Access List at Mayberry interface serial 0 ip access-group 44 10 Describe the types of packets that this filter would discard, and specify at what point they would be discarded. 11 Does the access list in Example 8-15 stop packets from getting to Web server Governor Why or why not 12 Referring to Figure 8-8, create and enable access lists so that access to Web server Governor is allowed from hosts at any site and so that no other access to hosts in Raleigh is allowed. 13 Name all...

Comment About Data Links

Because the routers build new data-link headers and trailers, and because the new headers contain data-link addresses, the routers must have some way to decide what data-link addresses to use. An example of how the router determines which data-link address to use is the IP Address Resolution Protocol (ARP) protocol. ARP is used to dynamically learn the data-link address of some IP host. An example specific to TCP IP will be useful to solidify the concepts behind routing. Imagine that PC1 is...

A JL

LOBaseT, using hub, simulates single bus lOBaseT, using hub, simulates single bus The concept of cabling each device to a central hub, with that hub creating the same electrical bus as in the older types of Ethernet, was a core fact of 10BaseT Ethernet. Because hubs continued the concept and physical reality of a single electrical path that is shared by all devices, today we call this shared Ethernet All devices are sharing a single 10-Mbps bus. So, hubs solved some cabling and availability...

Acknowledgments

I can write a 1000-page book, but I can't find enough words to describe the credit Chris Cleveland deserves for what is good about this book. Michael Jordan, Wayne Gretsky, Chris Cleveland a list of the absolutely best at what they do Chris, thanks for putting up with the hand-drawn figures, for meeting my schedule requirements, and for working hard during the holidays. Your ability to edit my style of writing and revising makes my job a breeze. I still refuse to write a book unless you develop...

Address Resolution Protocol

The Address Resolution Protocol (ARP) answers this question Given an IP address of another device on the same LAN, what is its MAC address ARP is needed because, to send an IP packet across some LANs, the data-link header and trailer (which encapsulate the packet) must first be created. The source MAC address in this new header is known because it is the MAC address of the sender. However, the destination MAC is not known in advance ARP is the method that IP uses to discover the destination MAC...

Answers to Scenario 102 Frame Relay Configuration

Check your IP and IPX address design against the ones chosen in Table 10-27. Of course, your choices most likely are different. However, you should have one subnet per VC when using only point-to-point subinterfaces. With the original criteria of Routers A, D, and E each using multipoint subinterfaces, these three subinterfaces should have been in the same IP subnet and IPX network. Table 10-27 lists the planned Layer 3 addresses for the configurations using multipoint among these three...

Answers to Scenario 103 Frame Relay Configuration Dissection

Figure 10-24 supplies the network diagram described in Scenario 10-3. The subinterfaces are all point-to-point, which is a clue that each VC has a subnet and IPX network associated with it. An examination of the IP addresses or IPX network numbers should have been enough for you to deduce which routers are attached to each end of each VC. Figure 10-24 Diagram of Scenario 10-3 Frame Relay Network Figure 10-24 Diagram of Scenario 10-3 Frame Relay Network Split horizon is turned off on all...

Answers to Scenario 112 IPX Configuration Answers to Task 1 for Scenario 112

Assuming the details established in Figure 11-25 for Scenario 11-2, you can find in Examples 11-24, 11-25, and 11-26 the IPX configurations on all three routers Mayberry, Mount Pilot, and Raleigh, respectively. Example 11-24 Mayberry Configuration, Scenario 11-2, Task 1 Example 11-25 Mount Pilot Configuration, Scenario 11-2, Task 1 Example 11-25 Mount Pilot Configuration, Scenario 11-2, Task 1 Example 11-26 Raleigh Configuration, Scenario 11-2, Task 1 Example 11-26 Raleigh Configuration,...

Answers to Scenario 42 LAN Switch Concepts

This scenario tests your recollection of a few of the core concepts for LAN switching. The answers are listed in succession 1 Ten collision domains exist in the network for this scenario. Routers and switches separate LANs into separate collision domains, but shared hubs do not. In this diagram, each switch port and the device(s) connected to it form the individual collision domains. 2 Two broadcast domains exist in this network. Switches and hubs do not separate the LAN segments into different...

Answers to Scenario 61 IP Addressing and Subnet Calculation

Assuming that you had issued the commands in Example 6-20, the most specific network diagram would look like Figure 6-46. Figure 6-46 Scenario 6-1 Answer Network with Router Fred Figure 6-46 Scenario 6-1 Answer Network with Router Fred The clues that you should have found in the show commands are as follows The types and IP addresses of the interfaces on Fred were in the show interface and show ip interface brief command output. The subnets could be learned from the show ip route command or...

Answers to Scenario 81 IP Filtering Sample

The solution to fulfilling the criteria stipulated for this access list is straightforward. Simply matching Grigory to permit his traffic and denying packets from 210.1.1.0 is all that is needed for the first two criteria. A permit all needs to be explicitly configured at the end of the list. Example 8-16 provides the solution for this scenario. The access list is enabled on Nova. The problem with list 43 is that if the link from Barnaul to Gorno goes down, and if Gorno learns a route to...

Answers to Scenario 83 IP Filtering Sample

Many solutions could fulfill the criteria stipulated for this scenario. The solutions provided in Examples 8-19 and 8-20 attempt to filter packets as close to the source of the packet as possible. It is impossible to determine whether your correct solution is better than the one given here without more information about traffic loads and business needs in the network. The comments included in Examples 8-19 and 8-20 provide most of the detailed commentary. Example 8-19 Solution to Scenario 8-3...

Answers to Scenario 91 Pointto Point Verification

Figure 9-20 is a diagram that matches the configuration. The IP and IPX addresses used on the various router interfaces were one of the tasks for this scenario. Table 9-35 is a completed version of Table 9-33, which was the blank table in which you recorded your answers for this task. Finding all the IP and IPX addresses in Examples 9-11, 9-12, and 9-13 requires some persistence. The best plan of attack is to find all the IP addresses and masks that you can, then find all the IPX network...

Answers to Task 1 for Scenario

Given the details in Figure 6-44 and Table 6-61 for Scenario 6-2, the subnet mask criteria are as follows 200 hosts in a subnet, maximum Static size masks used all over this network The mask must have at least eight host bits because 2' x 128 is not enough and 28 x 256 is more than enough for numbering 200 hosts in a subnet. The mask must have at least seven subnet bits, likewise, because 27 is the smallest power of 2 that is larger than 100, which is the required number of subnets. The first...

Answers to Task 2 for Scenario 112

Assuming the details established in Figure 11-25 for Scenario 11-2, the second task for Scenario 11-2 calls for additional encapsulations. Beatrice is using NetWare's Ethernet_II encapsulation, Floyd is using Ethernet_802.3, Barney is using Ethernet_802.2, and Governor is using Ethernet_SNAP. Hopefully you remembered the encapsulation names used in the IOS the names supplied in the problem statement use the NetWare names. (In real life, a simple question mark when typing the ipx network...

Answers to Task 2 for Scenario 114

Task 2 for Scenario 11-4 asks you to create IPX packet filters to meet the following criteria Clients in Nashville and Boston are not allowed access to Server 1. Clients in Charlotte are not allowed access to Server 2. Use standard access lists, if possible. Place the access lists close to the source of the packets. Assume that all access lists from Task 1 have been disabled and deleted. This can be accomplished by configuring standard IPX access lists. Because the goal is to filter packets...

Answers to Task 2 for Scenario

Based on the network design illustrated in Figure 3-23, Task 2 for Scenario 3-1 states that D'Artagnan sends a packet to Aramis (source group-1.local-M, destination group-4.local-M). D'Artagnan sends this packet inside an Ethernet frame to Router A. The following are the solutions to exercises 1 through 4 for Task 2. 1 The routing tables are as follows In Router A 2 Router A discards the Ethernet header and adds an HDLC header. Router B discards the HDLC header and adds an Ethernet header....

Other Cisco Certifications

Cisco has many other certifications as well, as summarized in Table 1-2. Refer to Cisco's Web site at for the latest information. Table 1-2 Additional Cisco Certifications Table 1-2 Additional Cisco Certifications The granddaddy of them all CCIE focused on routing and switching, and is the logical conclusion after getting CCNA and then CCNP. Cisco Certified Internetworking Professional is in concept like CCNP, with a focus on service CCIE, with a focus on service provider-oriented technologies....

Answers to Task 3 for Scenario 114

Task 3 for Scenario 11-4 asks you to create SAP filters that perform the same function as described in Task 2. Task 3 suggests a very simple solution, but the simple solution works only because there are local servers in Charlotte, Nashville, and Boston. First take a look at the solution then read over some comments. Because the local server in each case will be the GNS server for the local clients, respectively, all that is needed is to stop Server 1 and Server 2 SAP information from being...

Answers to Task 3 for Scenario

Based on the network design illustrated in Figure 3-23, Task 3 for Scenario 3-1 states that D'Artagnan sends a packet to Porthos (source group-1.local-M, destination group-6.local-M). D'Artagnan sends this packet inside an Ethernet frame to Router A. The following are the solutions to exercises 1 through 4 for Task 3. 1 The routing tables are as follows In Router A 2 Router A discards the Ethernet header and adds a Frame Relay header. Router D discards the Frame Relay header and adds an...

Answers to Task 4 for Scenario

Task 4 for Scenario 7-2 requires that you consider the effects of split horizon. Split-horizon logic considers subinterfaces to be separate interfaces, in spite of the fact that several subinterfaces share the same physical interface. Boston advertises 10.1.4.0 in its RIP update only out its subinterface 1. All other routes in Boston's routing table are learned through RIP updates from Atlanta via updates entering that same subinterface. Therefore, Boston does not advertise those routes in...

Answers to the Chapter 2 Do I Know This Already Quiz

1 What are the two different names for the router's mode of operation that, when accessed, enables you to issue commands that could be disruptive to router operations Enable and privileged mode. Both are commonly used and found in Cisco documentation. 2 What command would you use to receive command help if you knew that a show command option begins with a c but you could not recall the option You would use show c . Help would appear immediately after you typed the symbol. You would not need to...

Answers to the Chapter 3 Do I Know This Already Quiz

1 Name the seven layers of the OSI model. Application (Layer 7), presentation (Layer 6), session (Layer 5), transport (Layer 4), network (Layer 3), data link (Layer 2), and physical (Layer 1). 2 What is the main purpose(s) of Layer 3 The network layer defines logical addressing and routing as a means of delivering data across an entire network. IP and IPX are two examples of Layer 3-equivalent protocols. 3 What is the main purpose(s) of Layer 2 The data link layer defines addressing specific to...

Answers to the Chapter 5 Do I Know This Already Quiz

1 What routing protocol does a transparent bridge use to learn about Layer 3 addressing groupings None. Bridges do not use routing protocols. Transparent bridges do not care about Layer 3 address groupings. Devices on either side of a transparent bridge are in the same Layer 3 group in other words, the same IP subnet or IPX network. 2 What settings are examined by a bridge or switch to determine which should be elected as root of the spanning tree The bridge priority is examined first (the...

Answers to the Chapter 7 Do I Know This Already Quiz

1 Define what split horizon means to the contents of a routing update. Does this apply to both the distance vector algorithm and the link-state algorithm Routing updates sent out an interface do not contain routing information about subnets learned from updates entering the same interface. Split horizon is used only by distance vector routing protocols. 2 Describe the purpose and meaning of route poisoning. Route poisoning is the distance vector routing protocol feature in which a newly bad...

Approach

Retention and recall are the two features of human memory most closely related to performance on tests. This exam preparation guide focuses on increasing both retention and recall of the exam topics. The other human characteristic involved in successfully passing the exam is intelligence, but this book does not address that issue Adults' retention is typically less than that of children. For example, it is common for 4-year-olds to pick up basic language skills in a new country faster than...

Basic 1900 Switch Configuration

On the Catalyst 1900 switch, three different configuration methods exist Menu-driven interface from the console port Web-based Visual Switch Manager (VSM) IOS command-line interface (CLI) As mentioned earlier, this book focuses on using the CLI to configure the switch. Table 4-9 lists the switch commands referred to in this section. Table 4-9 Commands for Catalyst 1900 Switch Configuration Table 4-9 Commands for Catalyst 1900 Switch Configuration Sets the IP address for in-band management of...

Basic IP and Port Duplex Configuration

Two features commonly configured during switch installation are TCP IP support and the setting of duplex on key switch ports. Switches support IP, but in a different way than a router. The switch acts more like a normal IP host, with a single address mask for the switch and a default router. Each port interface does not need an IP address because the switch is not performing Layer 3 routing. In fact, if there were no need to manage the switch, IP would not be needed on the switch at all. The...

Basic RIP and IGRP Configuration

Each network command enables RIP or IGRP on a set of interfaces. You must understand the subtleties of the network command, as explained in this section. However, what enables really means in this case is not obvious from the Cisco IOS Software documentation. Also, the parameters for the network command are not intuitive to many people who are new to Cisco IOS configuration commands. Therefore, routing protocol configuration, including the network command, is a likely topic for tricky questions...

Basic VLAN Configuration

You should remember several items before you begin VLAN configuration The maximum number of VLANs is switch-dependent. The Catalyst 1900 supports 64 VLANs with a separate spanning tree per VLAN. VLAN 1 is one of the factory-default VLANs. CDP and VTP advertisements are sent on VLAN 1. Catalyst 1900 IP address is in the VLAN 1 broadcast domain. The switch must be in VTP server mode or transparent mode to create, add, or delete VLANs. Table 5-8 represents the commands covered in this section and...

Cidr

CIDR is a convention, defined in RFC 1817 (www.ietf.org rfc rfc1817.txt), that calls for aggregating multiple network numbers into a single routing entity. CIDR was actually created to help the scalability of Internet routers imagine a router in the Internet with a route to every Class A, B, and C network on the planet By aggregating the routes, fewer routes would need to exist in the routing table. Consider Figure 6-31. Class C networks 198.0.0.0 through 198.255.255.0 (they might look funny,...

Cisco Discovery Protocol

The Cisco Discovery Protocol (CDP) discovers basic information about neighboring routers and switches, without needing to know the passwords for the neighboring devices. CDP supports any LAN, HDLC, Frame Relay, and ATM interface. CDP supports any interface that supports the use of SNAP headers. The router or switch can discover Layer 2 and Layer 3 addressing details of neighboring routers without even configuring that Layer 3 protocol this is because CDP is not dependent on any particular Layer...

Cl n

Example 11-17 Albuquerque Command Output, Scenario 11-1 Albuquerque show ipx interface brief Albuquerque show cdp neighbor detail Platform cisco 2500, Capabilities Router Interface Serial0, Port ID (outgoing port) Cisco Internetwork Operating System Software IOS (tm) 2500 Software (C2500-AINR-L), Version Copyright 1986-1997 by Cisco Systems, Inc. Compiled Mon 29-Dec-97 18 47 by ckralik Platform cisco 2500, Capabilities Router Interface Serial1, Port ID (outgoing port) Cisco Internetwork...

Classes of Networks

RFC 790 defines the IP protocol, including three different sizes of networks. By definition, all addresses in the same network have the same numeric value network portion of the addresses. The rest of the address is called the host portion of the address. Using the post office example, the network part is the ZIP code, and the host part is the street address. Just as a letter-sorting machine three states away from you cares only about the ZIP code on a letter addressed to you, a router three...

Comparison of WAN Options

Networking professionals need to know about many WAN options when designing networks. Certainly, Cisco requires CCNAs to have a solid foundation of the WAN technologies described in this chapter. Cisco also expects CCNAs to be able to compare and contrast these different WAN technologies. This section summarizes many of the concepts found earlier in this chapter, with a focus on comparison. The permanent WAN connectivity options can be categorized into two main groups synchronous serial leased...

Compression

Compression can be performed on LAPB, HDLC, and PPP point-to-point serial links. The goal of compression is to reduce the number of bytes sent across the link. However, there is a price to pay for compression CPU cycles and possibly increased latency for the packets. The following list summarizes the trade-offs when you're considering whether to use compression More processing is required on the router to compress each frame, as compared with no compression. Latency per frame increases because...

Configuring Cisco IOS Software

43 Manage configuration files from the privileged exec mode. 47 Check an initial configuration using the setup command. 53 Prepare the initial configuration of your router and enable IP. You must understand how to configure a Cisco router to succeed on the exam or to succeed in supporting Cisco routers. This section covers the basic configuration processes, including the concept of a configuration file and the locations in which the configuration files can be stored. As mentioned in Chapter 1,...

Connection Establishment and Termination

TCP connection establishment occurs before any of the other TCP features can begin their work. Connection establishment refers to the process of initializing sequence and acknowledgment fields and agreeing to the port numbers used. Figure 6-13 shows an example of connection establishment flow. Figure 6-13 TCP Connection Establishment SEQ 1450, ACK 201 SYN, ACK, DPORT 1027, SPC> RT 80 This three-way connection-establishment flow must complete before data transfer can begin. The connection...

Contents at a Glance

Chapter 1 All About the Cisco Certified Network Associate Certification 3 Chapter 2 Cisco IOS Software Fundamentals 27 Chapter 3 OSI Reference Model and Layered Communication 79 Chapter 4 LANs, Bridges, and Switches 145 Chapter 5 Intermediate LANs Spanning Tree, VLANs, and Trunking 215 Chapter 6 TCP IP and IP Routing 267 Chapter 7 Routing and Routing Protocols 407 Chapter 8 Understanding Access List Security 489 Chapter 9 WAN Protocols and Design 533 Chapter 10 Frame Relay Concepts and...

Controlling vty Access with IP Access Lists

Access into and out of the virtual terminal line (vty) ports of the Cisco IOS software can be controlled by IP access lists. (vty is used for Telnet access to and from the Cisco IOS software.) The inbound case is the more obvious case. For instance, imagine that only hosts in subnet 10.1.1.0 24 are supposed to be capable of Telnetting into any of the Cisco routers in a network. In such a case, the configuration in Example 8-14 could be used on each router to deny access from IP addresses not in...

Data Link Function 2 Addressing

Cisco requires that CCNAs master the formats and meanings of data link layer and network layer addresses. LANs need addressing because there can be many possible recipients of data that is, there could be more than two devices on the link. LANs behave much like people when you have a meeting with three or more people If you want to say something to someone in particular, you first say that person's name or at least look at him. Or, if you want to tell everyone in the meeting something, you just...

DDR Legacy Concepts and Configuration

You can configure DDR in two ways DDR legacy and DDR dialer profiles. The main difference between the two is that DDR legacy associates dial details with a physical interface, whereas DDR dialer profiles disassociate the dial configuration from a physical interface, allowing a great deal of flexibility. The concepts behind DDR legacy apply to DDR dialer profiles as well, but DDR legacy is a little less detailed. Although it's not overly stated in the course, the DDR coverage in the ICND class...

DDR Step 1 Routing Packets Out the Interface to Be Dialed

Figure 9-13 provides the backdrop for these discussions. In these discussions, the SanFrancisco router dials into the main site in LosAngeles. The router must choose when to dial. The first step in this process relates to the following fact DDR does not dial until some traffic is directed (routed) out the dial interface. The router needs to route packets so that they are queued to go out the dial interface. Cisco's design for DDR defines that the router receives some user-generated traffic and,...

DDR Step 2 Determining the Subset of the Packets That Trigger the Dialing Process

Together, Steps 1 and 2 of legacy DDR logic determine when the dial is attempted. These combined steps are typically called triggering the dial. In Step 1, a packet is routed out an interface to be dialed, but that packet alone does not necessarily cause the dial to occur. The Cisco IOS Software allows the second step to define a subset of the packets routed in Step 1 to actually cause the route to dial. The logic flow is as shown in Figure 9-14. The choice in Step 2 is simply put like this Is...

DDR Step 3 Dialing Signaling

The dialing router needs additional information before the dial can occur. First, for non-ISDN interfaces, it is necessary to communicate the dial string to the external dialing device. In-band signaling (dialing) must be enabled on these interfaces using the command dialer in-band. This is not necessary on a BRI interface, because it uses the out-of-band D channel for signaling. Table 9-17 summarizes what this command implies on different interfaces. Table 9-17 Effect of the dialer in-band...

Deciding What the Other Subnets

When I wrote the four-step process section for IP subnetting, I had two goals in mind. As I mentioned earlier, you need to answer subnetting questions quickly and confidently on the exam. Network engineers also think about subnetting every day, so it's great to be able to do the math in your head. So far, you have dealt with questions regarding a single subnet. You might also need to address the question What are the other valid subnets of this network The details of answering this question...

Distance Vector Routing Protocol Behavior

CCNAs deal with routing problems on a daily basis. Some of these problems are the result of the logic behind distance vector routing protocols. Understanding what distance vector routing means is to understand how a routing protocol accomplishes the following goals Learning routing information Adding the current best route after one has failed The following list summarizes the behavior of a router that uses the RIP-1 or IGRP distance vector routing protocols Routers add directly connected...

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. This 12-question quiz helps you determine how to spend your limited study time. The quiz is sectioned into three smaller four-question quizlets, which correspond to the three major topic headings in the chapter. Figure 2-1 outlines suggestions on how to spend your time in this chapter...

Electing the Root Discovering Root Ports and Designated Ports

Each bridge begins by claiming to be the root bridge by sending STP messages. STP defines these messages used to exchange information with other bridges, which are called bridge protocol data units (BPDUs). Each bridge begins by sending a BPDU stating the following The root bridge's bridge ID At the beginning of the process, each bridge claims to be root, so this value is the same as the bridge ID of this bridge. An administratively set priority This is the priority of the root bridge. At the...

Error Recovery

Cisco expects CCNAs to be able to distinguish between error detection and error recovery. Any header or trailer with a frame check sequence (FCS) or similar field can be used to detect bit errors in the PDU. The FCS uses some magic math against the contents of the frame, with the result recorded in the FCS field. If the receiving device repeats the same math but gets a different value than what is in the FCS field, there were bit errors in transmission. Error detection uses the FCS to detect...

Error Recovery Reliability

TCP provides for reliable data transfer, which is also called reliability or error recovery, depending on what document you read. To accomplish reliability, TCP numbers data bytes using the sequence and acknowledgment fields in the TCP header. TCP achieves reliability in both directions, using the Sequence Number field of one direction combined with the Acknowledgment Field in the opposite direction. If you remember error recovery from Chapter 3, OSI Reference Model and Layered Communication,...

Examination of RIP and IGRP debug and show Commands

Figure 7-10 Sample Three-Router Network with Subnet 10.1.2.0 Failing Figure 7-10 Sample Three-Router Network with Subnet 10.1.2.0 Failing Example 7-4 RIP Configuration and debugs on Albuquerque received v1 update from 10.1.6.253 on Seriall 10.1.3.0 in 1 hops 10.1.2.0 in 2 hops 10.1.5.0 in 1 hops sending v1 update to 255.255.255.255 via Serial0 (10 (POINT NUMBER 1) subnet subnet subnet sending v1 subnet subnet subnet sending v1 subnet subnet subnet subnet subnet update to 255.255.255.255 via...

Example Layer 3 Address Structures

Each Layer 3 address structure contains at least two parts. One (or more) part at the beginning of the address works like the ZIP code and essentially identifies the grouping. All instances of addresses with the same value in these first bits of the address are considered to be in the same group for example, the same IP subnet or IPX network or AppleTalk cable range. The last part of the address acts as a local address, uniquely identifying that device in that particular group. Table 3-10...

Extended IP Access Lists Example

The first example is basic in order to cover the statements syntax. In this case, Bob is denied access to all FTP servers on R1's Ethernet, and Larry is denied access to Server1's Web server. Figure 8-6 is a reminder of the network topology. In Example 8-6, an access list is created on R1. Example 8-6 shows the configuration on R1. Figure 8-6 Network Diagram for Extended Access List Example 1 Figure 8-6 Network Diagram for Extended Access List Example 1 Example 8-6 R1's Extended Access List...

Fast Ethernet and Gigabit Ethernet

Fast Ethernet and Gigabit Ethernet provide faster Ethernet options. Both have gained widespread acceptance in networks today, with Fast Ethernet most likely being used to the desktop and Gigabit Ethernet being used between networking devices or to servers. Fast Ethernet retains many familiar features of 10-Mbps Ethernet variants. The age-old CSMA CD logic still exists, but it can be disabled for full-duplex point-to-point topologies in which no collisions can occur. A variety of cabling options...

Flow Control

Flow control is the process of controlling the rate at which a computer sends data. Depending on the particular protocol, both the sender and the receiver of the data (as well as any intermediate routers, bridges, or switches) might participate in the process of controlling the flow from sender to receiver. Flow control prevents unnecessary congestion by attempting to send data at a rate that the network can currently accomodate. A sender of data might be sending the data faster than the...

Foundation Summary

The Foundation Summary is a collection of tables and figures that provide a convenient review of many key concepts in this chapter. For those of you already comfortable with the topics in this chapter, this summary could help you recall a few details. For those of you who just read this chapter, this review should help solidify some key facts. For any of you doing your final preparation before the exam, these tables and figures will be a convenient way to review the day before the exam. The...

Foundation Topics Spanning Tree Protocol

1 Describe the operation of the Spanning Tree Protocol and its benefits. In the absence of STP, frames would loop for an indefinite period of time in networks with physically redundant links. STP blocks some ports so that only one active path exists between any pair of LAN segments (collision domains). The result of STP is both good and bad Frames do not loop infinitely, which makes the LAN usable, which is good. However, the network does not actively take advantage of some of the redundant...

Foundation Topics The Cisco IOS Software Command Line Interface

42 Examine router elements (RAM, ROM, CDP, show). 44 Control router passwords, identification, and banner. 45 Identify the main Cisco IOS Software commands for router startup. 46 Log in to a router in both user and privileged modes. 48 Use the context-sensitive help facility. 49 Use the command history and editing features. The majority of Cisco routers run Cisco IOS Software, with its familiar command-line interface (CLI). Some routing cards in other devices also run Cisco IOS Software. For...

HDLC and PPP Configuration

One common task for CCNAs is to enable an appropriate point-to-point data-link protocol. The configuration is straightforward, with LAPB being the exception. Be sure to configure the same WAN data-link protocol on each end of the serial link. Otherwise, the routers will misinterpret the incoming frames, and the link will not work. Tables 9-4 and 9-5 summarize the configuration commands and the show and debug commands used for HDLC and PPP configuration. Table 9-4 PPP and HDLC Configuration...

How Spanning Tree Works

The STP algorithm creates a spanning tree of interfaces that either forward or block. STP actually places interfaces into forwarding state by default, if an interface has no reason to be in forwarding state, it is placed into a blocking state. In other words, STP simply picks which interfaces should forward. So, how does STP choose whether to put an interface into forwarding state Well, it uses three criteria STP elects a root bridge. All interfaces on the root bridge are in forwarding state....

How This Book Is Organized

This book contains 10 core chapters Chapters 2 through 11. Each chapter covers a subset of the topics on the exam. Along with these core chapters, three other chapters help you succeed on the CCNA exam. Chapter 1 helps you understand how to use this book to efficiently and effectively study for the CCNA exam. Chapter 12 is full of lab scenarios that force you to think about all the topics in the book, which helps you with final preparation. And, if you can get access to some lab gear, read...

How to Best Use This Chapter

By taking the following steps, you can make better use of your study time Keep your notes and the 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 that retention is significantly increased through writing down facts and concepts, even if you never look at the information again. Use the diagram in Figure 3-1 to guide you to the next step.

IGRP Metrics

This metric is calculated as a function of bandwidth, delay, load, and reliability. By default, only bandwidth and delay are considered the other parameters are considered only if they are enabled via configuration. Delay and bandwidth are not measured values but are set via the delay and bandwidth interface subcommands. (The same formula is used to calculate the metric for EIGRP, but with a scaling factor so that the actual metric values are larger, allowing more...

Im New to Internetworking with Cisco I Will Not Be Taking the ICND Course and I Bought the Interconnecting Cisco

If you have no networking experience at all, start with the ICND book. The CCNA exam lists ICND as the main prerequisite course before taking the exam. The Cisco Press ICND book contains the actual ICND course materials, handed over by Cisco to Cisco Press, and then converted into book format. The same figures used in the presentations by instructors are used as the figures in the book, with explanations matching what a senior instructor might say when teaching the course. So, if you use one...

Info

Source Destination Source Destination 10.1.1.1 170.1.1.1 200.1.1.1 170.1.1.1 Source Destination Source Destination 170.1.1.1 10.1.1.1 170.1.1.1 200.1.1.1 NAT also can be used when the private organization is not using private addressing but is instead using a network number registered to another company. (A client company of mine originally had done just that ironically, the company was using a network number registered to Cabletron, which my client saw used in a presentation by an ex-Cabletron...

IP Addressing with Frame Relay Subinterfaces

Frame Relay behaves like a WAN in some ways and more like a LAN in other ways. To overcome some routing protocol issues that will be discussed in Chapter 7, Routing and Routing Protocols, and Chapter 10, Frame Relay Concepts and Configuration, Cisco provides three different ways to configure IP addresses on Frame Relay serial interfaces 1 Configure the IP addresses on the normal physical interface, just like for other interfaces. By doing so, all routers on the Frame Relay network are in the...

IP Configuration

You can easily configure a Cisco router to forward IP traffic when you know the details covered in this chapter so far. Tables 6-48 and 6-49 summarize many of the most common commands used for IP configuration and verification. Two sample network configurations, with both configuration and exec command output, follow. The Cisco IOS documentation is an excellent reference for additional IP commands the Cisco Press book Interconnecting Cisco Network Devices is an excellent reference, particularly...

IP Naming Commands and Telnet

When using the IOS CLI, you will want to refer to names instead of IP addresses. Particularly for the trace, ping, and telnet commands, the IP address or host name must be supplied. This section describes the use of host names on an IOS-based device. Along the way, some nuances of the use of Telnet are covered. The IOS can use statically configured names as well as refer to one or more DNSs. Example 6-13 shows some names statically configured, with configuration pointing to two different DNSs....

ISDN Channels

The IOS documentation focuses on two types of ISDN interfaces Basic Rate Interface (BRI) and Primary Rate Interface (PRI). Both BRI and PRI provide multiple digital bearer channels over which temporary connections can be made and data can be sent. The result is concurrent digital dial access to multiple sites. Table 9-9 summarizes the features of BRI and PRI. Bearer channels (B channels) are used to transport data. B channels are called bearer channels because they bear the burden of...

ISDN Configuration

Examples 9-8 and 9-9 show the DDR configuration for the network shown in Figure 9-15. ISDN configuration details have been added. The text following these two examples describes the ISDN commands shown. Example 9-8 Completed SanFrancisco Configuration ip route 172.16.3.0 255.255.255.0 172.16.2.1 ip route 172.16.4.0 255.255.255.0 172.16.2.3 Added usernames for CHAP support username LosAngeles password Clark username GothamCity password Bruce access-list 101 permit tcp any host 172.16.3.1 eq 80...

Issues When Multiple Routes to the Same Subnet Exist

A router might learn one route and then learn a better route. Of course, the better route should replace the higher-metric route when this happens. Figure 7-4 outlines just such a case. Table 7-6 shows Router B's routing table when only one route to 162.11.10.0 is known, before the serial link between B and C comes up. Table 7-7 shows Router B's routing table after the link between B and C comes up, learning about another route to that same subnet. Figure 7-4 Routers A and C Advertising to...

Ive Taken the Cisco Networking Academy Courses Now What

First of all, congratulations on having the foresight to get into the Cisco Networking Academy program we need more people who can make this stuff work (Those of you who didn't take the Cisco Networking Academy track and are wondering what it's all about can check out Thankfully, the Networking Academy curriculum actually does a great job of preparing you with the skills and knowledge you need to pass the exam. Unfortunately, your study was probably spread over several semesters, and possibly...

Lab 1 Hints

I searched for console connection on www.cisco.com, and I found this pointer that might be helpful If you do everything right but forget to press Enter, the router or switch will not write anything to the screen. You will not hurt anything by pressing Enter too many times Always try a different console cable and connector, make sure the cables are connected well, and make sure the cable is plugged into the console port, not the auxiliary port. Use the disable and enable commands to move back...

Lab 2 Hints

I searched for console connection on www.cisco.com, and found this pointer that may be helpful c2520ins.htm xtocid894612 Always try a different console cable and connector, make sure the cables are connected well, and make sure the cables are plugged into the console port, not the aux port. Use the disable and enable commands to move back and forth. Use the show interfaces ethernet 0 1 command. Use the command to find the hostname command. The right command would be something like hostname...

Lab 2 Stepby Step Instructions

Step 1 Connect the console cable between your PC's COM1 port and a switch's console port. Step 2 Bring up your favorite terminal emulator program. If you do not have a favorite, use HyperTerminal, which comes with Microsoft operating systems. Select Start, Programs, Accessories, Communications, HyperTerminal. Step 3 Ignore attempts to make you configure a phone number, but configure terminal characteristics of 9600 bps, 8 bits byte, no parity, and 1 start stop bit. This combination is often...

Lab 4 Stepby Step Instructions

Step 1 Log in to Rl, and use the write erase command to clear NVRAM. Step 2 Issue the reload command to reload your router. What configuration will the router use when reloading Step 3 After the router has reloaded, you are asked if you want to enter the initial configuration dialogue. Type yes. Step 4 You are prompted with a series of commands. These commands expect a response from you. If there is a default answer, it is shown in brackets at the end of the command. You can just press Enter if...

Lab 5 Stepby Step Instructions

Step 2 You should be able to ping 172.30.102.2, R2's serial IP address, but not 172.30.103.2, R2's Ethernet IP address. The ping to 172.30.103.2 does not work, because R1 does not have a route to 172.30.103.0 24, the subnet in which 172.30.103.2 resides. Step 3 Verify the contents of the routing table on R1. What command did you use How many routes are in the routing table Step 4 On R1, configure a static route pointing to subnet 172.30.103.0. Step 5 On R1, ping 172.30.103.2. Does it work now...

Lab 6 Stepby Step Instructions

Step 2 Verify that you can ping 172.30.103.2, R2's EthernetO IP address. Likewise, verify that you can Telnet to that same address. Step 3 After you have Telnetted to R2, configure the Web server feature on R2 using the ip http server configuration command. Save your configuration on R2. Step 5 From R1, you can use the telnet command to test whether the Web server on R2 is responding, using a trick. From R1, use the command telnet 172.30.103.2 80. This command uses Telnet, but it tries to...

Lab 7 WAN Configuration

This lab assumes that you have completed Labs 4 and 5, in which you configured IP addresses and routing protocols. This lab assumes that you know how to get around the user interface on the routers. This lab focuses on reviewing the most important commands from Chapter 9, WAN Protocols and Design, and Chapter 10, Frame Relay Concepts and Configuration. This lab requires that you use three routers, with one configured as a Frame Relay switch. Figure 13-3 outlines the physical and logical...

Lab 8 Novell IPX Configuration

This lab assumes that you have completed Labs 4 and 5, in which you configured IP addresses and routing protocols. This lab assumes that you know how to get around the user interface on the routers. This lab focuses on reviewing the most important commands from Chapter 11, Novell IPX. Figure 13-4 outlines the IPX network numbering. Figure 13-4 Novell IPX Network Numbers for Lab 8 When finished with this lab, you will be able to do the following Configure Novell routing and RIP Step 1 Revert to...

LAN Addressing

LAN addressing identifies either individual devices or groups of devices on a LAN. On the CCNA exam, you are expected to confidently understand and interpret LAN addresses. Unicast addresses identify a single LAN card. Frames between a pair of LAN stations use a source and destination address field to identify each other. These addresses are called unicast addresses, or individual addresses, because they identify an individual LAN interface card. (The term unicast was chosen mainly for contrast...

LAN Framing

Framing defines how a string of binary numbers is interpreted. For example, Ethernet defines how the first several bytes of a received electrical signal are interpreted after that signal is received and converted into a binary string. Figure 4-7 shows the details of several type LAN frames. 7 1 6 6 2 1 1 1-2 Variable 4 7 1 6 6 2 1 1 1-2 Variable 4 4 11 6 6 111-2 Variable 4 .5 1.5 4 11 6 6 111-2 Variable 4 .5 1.5 4 1 1 6 6 1 1 1-2 5 Variable 4 .5 1.5 4 1 1 6 6 1 1 1-2 5 Variable 4 .5 1.5 Don't...

Layering Concepts and Benefits

Many benefits can be gained from the process of breaking up the functions or tasks of networking into smaller chunks, called layers, and defining standard interfaces between these layers. The layers break a large, complex set of concepts and protocols into smaller pieces, making it easier to talk about, to implement with hardware and software, and to troubleshoot. The following list summarizes the benefits of layered protocol specifications Humans can more easily discuss and learn about the...

List of Labs

Table 13-1 describes the labs in this chapter. Router Command-Line Interface Familiarization The main goal of this lab is to make you familiar with getting around the router CLI. This lab offers you hints, ensuring that you understand the basics. 1900 Series Switch Command-Line Interface Familiarization The main goal of this lab is to make you familiar with getting around the switch CLI. This lab offers you hints, ensuring that you understand the basics. 1900 Series Switch VLANs, Trunks, and...

Managing Configuration and System Files

Commands that are used to manage and control the configuration and system software files are slightly different on the 1900 switch family than on IOS-based routers. One of the reasons for the difference is that the switch does not actually run IOS it has many features similar to IOS, including the IOS CLI, but there are and probably always will be some differences. For example, in Example 4-6, the familiar show version command is used to display uptime and software levels, but it does not show...

Mbps Ethernet

Ethernet is best understood by first considering the early 10Base5 and 10Base2 specifications. These two Ethernet specifications defined the details of the physical layer of early Ethernet networks. With these two specifications, the engineer installs a series of coaxial cables to each device on the Ethernet network there is no hub, switch, or wiring panel. The series of cables creates an electrical bus that is shared among all devices on the Ethernet. Because it is a single bus, only one...

MTU and Fragmentation

The maximum transmission unit (MTU) is a concept that implies the largest Layer 3 packet that can be forwarded out an interface. The maximum MTU value allowed is based on the data-link protocol essentially, the maximum size of the data portion of the data-link frame (where the packet is placed) is the maximum setting for the MTU on an interface. The default MTU value on Ethernet and serial interfaces is 1,500. If an interface's MTU is smaller than a packet that must be forwarded, fragmentation...

Multiplexing

In this context, multiplexing defines the process by which a host decides, among all its applications, which one should be given the incoming data. In the overview in the previous section, Jessie needed to decide whether to give the incoming data to the ad application, the wiretransfer application, or the web server application that process is what we call multiplexing. Multiplexing relies on the use of a concept called a socket. A socket consists of three things an IP address, a transport...

Network Address Translation

NAT is an RFC-defined function implemented in IOS that allows a host that does not have a valid registered IP address to communicate with other hosts through the Internet. The hosts might be using private addresses or addresses assigned to another organization in either case, NAT allows these addresses that are not Internet-ready to continue to be used but still allow communication with hosts across the Internet. NAT achieves its goal by using a valid registered IP address to represent the...

Nonroutable Protocols

In the early and mid-1990s, one of the reasons that Cisco sold a lot of routers is that the IOS could route more Layer 3 protocols than most if not all competitors. However, some protocols are not routable. To support those, Cisco supported and evolved variations of bridging to support nonroutable protocols. What makes a protocol nonroutable Basically, a protocol stack that does not define an OSI Layer 3 equivalent, including a logical Layer 3 address structure, cannot be routed. To be fair,...

Numbering Ports Interfaces

The terms interface and port both are used to describe the physical connectors on the switch hardware. For instance, the show running-config command uses the term interface the show spantree command uses the term port. The numbering of the interfaces is relatively straightforward the interface numbering convention for the 1912 and 1924 switches is shown in Table 4-10. Example 4-1 shows three exec commands and highlights the use of the terms interface and port. Table 4-10 Catalyst 1912 and 1924...

OSI Data Link Layer Functions

5 Describe data-link and network addresses, and identify key differences between them. 6 Define and describe the function of a MAC address. As a CCNA, you'll need to understand both the abstract concepts about the OSI layers and particular instances of such protocols. This section focuses on more of the abstract concepts. Later chapters provide more details about particular LAN and WAN data-link protocols, as well as their configuration in the IOS. This section examines four different protocols...

OSI Reference Model and Layered Communication

In years past, the need to understand the Open System Interconnection (OSI) reference model for networking grew rapidly. The U.S. government passed laws requiring vendors to support OSI software on their systems if vendors did not offer this support, the government would no longer buy the systems. Several vendors even predicted that the global Internet would evolve toward using the OSI protocols instead of TCP IP. As the century turns, however, OSI has been implemented on a much smaller scale...

Overview of Routing Protocols

Several routing protocols for TCP IP exist. IP's long history and continued popularity have called for the specification and creation of several different competing options. So, classifying IP routing protocols based on their differences is useful and also is a fair topic for exam questions. For the CCNA exam, you must know the terminology and routing protocols discussed here. You must also have a deeper understanding of distance vector protocols, which are described in upcoming sections....

Questions on Scenario

1 If this is all the information that you have, what IOS do you expect will be loaded when the user reloads Nova 2 Examine the following command output in Example 2-10, taken immediately before the user is going to type the reload command. What IOS do you expect will be loaded Example 2-10 show ip route Command Output for Nova Nova show ip route Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA...

RIP and IGRP

To pass the CCNA exam, you need to know the particulars of how RIP and IGRP implement distance vector logic. RIP and IGRP both use distance vector logic, so they are similar in many respects. A couple of major differences exist, however they are explained in the upcoming section. Table 7-12 outlines the features of RIP and IGRP. Table 7-12 RIP and IGRP Feature Comparison Table 7-12 RIP and IGRP Feature Comparison Function of bandwidth and delay (the default). Can include reliability, load, and...

RIP Version

RIP-2, defined by RFC 1723, adds advanced features to RIP-1. Many features are the same Hop count is still used for the metric, it is still a distance vector protocol, and it still uses hold-down timers and route poisoning. Several features have been added. They are listed in Table 7-16. Transmits a subnet mask with the route This feature allows VLSM by passing the mask along with each route so that the subnet Both clear text (RFC-defined) and MD5 encryption (a Cisco-added feature) can be used...

Router Memory Processors and Interfaces

The configuration file contains the configuration commands that you have typed, as well as some configuration commands entered by default by the router. The configuration file can be stored in a variety of places, including two inside a router. The router has a couple of other types of memory as well RAM Sometimes called DRAM for dynamic random-access memory, RAM is used by the router just as it is used by any other computer for working storage. The running or active configuration file is...