A

In Figure 5-4, the acknowledgment field in the TCP header sent by the Web server implies the next byte to be received this is called forward acknowledgment. The sequence number reflects the number of the first byte in the segment. In this case, each TCP segment is 1000 bytes in length the sequence and acknowledgment fields count the number of bytes. Figure 5-5 depicts the same scenario, but the second TCP segment was lost or in error. The Web server's reply has an ACK field equal to 2000,...

A a

Table 6-32 Subnets and Broadcast Addresses Table 6-32 Subnets and Broadcast Addresses Table 6-32 Subnets and Broadcast Addresses (Continued) Table 6-32 Subnets and Broadcast Addresses (Continued) Example 6-24 Scenario 6-3, show Commands on Router Mayberry 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 external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external...

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...

Address Resolution Protocol

One common problem that CCNAs deal with on a regular basis is this Given some Layer 3 address, what is its corresponding Layer 2 address Address Resolution Protocol (ARP) is the process by which this question is answered for an IP host on a LAN. ARP is needed because to send an IP packet across some LAN, the data link header and trailer (which encapsulate the packet) must first be created. The source MAC address in this new header is known, but the destination MAC is not known in advance ARP is...

Answers to Scenario 54 IPX Examination

Assuming the details established in Figure 5-46 and the command output in Example 5-29, Example 5-30, and Example 5-31 for Scenario 5-4, the show ipx interface brief command and show ipx route command are the best methods for learning the network numbers in Table 5-52 (Task 1, for this scenario). Table 5-52 IPX Networks in Scenario 5-4 Completed Chart Table 5-52 IPX Networks in Scenario 5-4 Completed Chart (Continued) Table 5-52 IPX Networks in Scenario 5-4 Completed Chart (Continued) Assuming...

Answers to Scenario 73 IP Filtering Sample

Many solutions could fulfill the criteria stipulated for this scenario. The solutions provided in Examples 7-24 and 7-25 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, or vice versa, without more information about traffic loads and business needs in the network. Comments shown inside the configurations in Example 7-24 and Example 7-25 provide most of the detailed...

Answers to Scenario 74 IPX Filtering

Refer to the network illustrated in Figure 7-14 and Examples 7-17 through 7-20 to establish the Scenario 7-4 design details and the context of the answers to the three tasks for this scenario. Task 1 for Scenario 7-4 asks you to characterize the traffic that is discarded due to the access lists used on Atlanta. Furthermore, you need to determine whether clients in the remote sites can access the servers in Atlanta. The answer is not obvious in this case. The extended access list is particularly...

Answers to Task 1 for Scenario

Task 1 for Scenario 6-1 asks for completed configurations, which are shown in Example 6-30, Example 6-31, and Example 6-32. You could have chosen different IP addresses, but your choices must have had the same first three octets as those shown in Example 6-30. Example 6-30 Albuquerque Configuration for Scenario 6-1 enable secret 5 1 ZvR Gpk5a5K5vTVpotd3KUygA1 1 Example 6-31 Yosemite Configuration for Scenario 6-1 enable secret 5 1 ZvR Gpk5a5K5vTVpotd3KUygA1 interface Serial0 ip address...

Answers to Task 2 for Scenario

To choose a mask and pick enough subnets to use for the original topology illustrated in Figure 5-44, a review of the longer binary algorithm and shortcut algorithm for deriving subnet numbers is required. To review, subnet numbers have the network number binary value in the network portion of the subnet numbers and have all binary 0s in the host bits. The bits that vary from subnet to subnet are the subnet bits in other words, you are numbering different subnets in the subnet field. Valid...

Answers to Task 3 for Scenario

Based on the network design illustrated in Figure 3-22, 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 6-4 asks you to examine the show ipx servers command from Seville. Furthermore, this task asks you to determine how many file servers appear to be in the SAP table, what socket Bugs is using, and, assuming defaults for ticks on each router, whether it is possible that more than one serial link exists in the route between Seville and Daffy. Two file servers are listed in the SAP table Bugs and Daffy. Both are using socket 451, as shown under the word port in the SAP table....

Binary Algorithm for Deriving the Network Number No Subnetting in

When a computer needs to answer this same question, it performs a Boolean math operation called AND between the address in question and the mask. The result of the AND operation is that the host bits are masked out that is, changed to binary 0s. The binary process, with no subnetting, is as follows Step 1 Write down the IP address in binary. Step 2 Write down the default mask appropriate for the class of address, in binary, beneath the binary IP address from Step 1. Step 3 Record the results of...

Binary Algorithm for Deriving the Subnet Number Basic Subnetting

The binary algorithm to determine the subnet number, when using basic subnetting, is practically identical to the algorithm used when there is no subnetting. Again, the key is in knowing what subnet mask is in use. The binary process, with basic subnetting, is as follows Step 1 Write down the IP address in binary. Step 2 Write down the subnet mask used in this network, in binary, beneath the binary IP address from Step 1. Step 3 Record the results of the Boolean AND below the two numbers. Step...

Binary Algorithm for Deriving the Subnet Number Difficult Subnetting

Difficult subnetting is a term used in this book to denote subnetting when the mask is not all 255s and 0s. The decimal algorithm for calculating the subnet, when basic subnetting is in use, is more challenging. In fact, several math tricks come in handy so that the result can be calculated without thinking about binary math. However, starting with the binary algorithm is helpful. These difficult masks typically contain one of the values shown in Table 5-17. To speed up the process of examining...

Bridges Switches and LAN Design

Cisco folklore tells of the day in 1998 when Cisco's revenues from LAN switching and hub products exceeded router revenues. That event in Cisco's history was significant because most people in the marketplace thought of Cisco as that router company for a long time. In fact, Cisco would prefer to even shake the reputation as a great router switch hub company and instead be known for empowering the Internet generation, a catch-phrase from the company's television ads. So, if switches and hubs...

Cisco Discovery Protocol

Cisco Discovery Protocol (CDP) is used by Cisco routers and switches to ascertain basic information about neighboring routers and switches. You can use this information to learn addresses quickly for easier Simple Network Management Protocol (SNMP) management, as well as learn the addresses of other devices when you do not have passwords to log in to the other device. CDP is a Cisco proprietary protocol to support forwarding CDP messages over an interface, that interface must support SNAP...

Classes of Networks

Class A, B, and C networks provide three network sizes. 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. Individual addresses in the same network all have a different value in the host parts of the addresses but have identical values in the network part. Class A networks have a 1-byte-long network part. That leaves 24 bits for the rest of the address, or the host...

Comparing 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. One major classification of IP routing protocols is whether they are optimized for creating routes inside one organization or routes between two or more interconnected organizations. Exterior routing...

Comparison of LAN Segmentation Using Bridges Switches and Routers

Cisco expects CCNAs to have command of the tradeoffs involved when designing campus LANs. One key consideration is to understand the different behavior when separating, or segmenting, LAN segments with some switching device. All the concepts related to LAN segmentation using bridges, switches, and routers are included in other parts of this chapter or in other chapters. However, the comparisons made in this section are important and would be missed if this book simply covered the technical...

Configuration of IPX

As seen in Chapter 5, enabling RIP and SAP on a router is very straightforward. The ipx routing command enables both in a router, and the ipx network command on an interface implies that RIP and SAP updates should be sent and listened for on those interfaces. Router Yosemite has been configured for RIP and SAP (see Figure 6-15). The command output in Example 6-21 shows the result of some RIP and SAP show and debug commands. (Do not forget the CCNA exam will ask questions about what commands can...

Configuration of RIP and IGRP

The CCNA exam requires you to understand RIP and IGRP configuration details. RIP and IGRP configuration requires an understanding of two subtle nuances namely, what the network command really implies and how the router interprets the network command. Other than these two details, configuration is relatively easy. Hands-on experience is the best way to fully learn the details of configuration. In lieu of that, this section lists commands, provides examples, and points out any tricky features....

Configuring Tunneling

Tunneling configuration is not very complicated if you remember the framing with the transport, encapsulation, and passenger protocols. A tunnel interface is created on each router at the ends of the tunnel. To accommodate the transport protocol, an IP address is used at the endpoints of the tunnel these IP addresses are used as the source and destination IP addresses of the encapsulated packets. The type of encapsulation protocol is configured there are six alternatives. Finally, the tunnel...

Contents at a Glance

Chapter 1 All About the Cisco Certified Network Associate Certification 2 Chapter 2 Cisco Internetwork Operating System (IOS) Fundamentals 20 Chapter 3 OSI Reference Model & Layered Communication 68 Chapter 4 Bridges Switches and LAN Design 128 Chapter 5 Network Protocols 210 Chapter 7 Understanding Access List Security 454 Chapter 8 WAN Protocols and Design 514 Chapter 9 Scenarios for Final Preparation 638 Appendix A Answers to the Do I Know This Already Quizzes and Q& A Sections 700...

Data Link Function 2 Addressing

Cisco requires that CCNAs master the formats and meanings of data link and network layer addresses. Addressing is needed on LANs because there can be many possible recipients of data that is, there could be more than two devices on the link. Because LANs are broadcast media a term signifying that all devices on the media receive the same data each recipient must ask the question, Is this frame meant for me With Ethernet and Token Ring, the addresses are very similar. Each uses Media Access...

Data Link Function 4 Identifying the Encapsulated Data

Finally, the fourth part of a data link identifies the contents of the data field in the frame. Figure 3-13 helps make the usefulness of this feature apparent. Figure 3-13 Multiplexing Using Data Link Type and Protocol Fields When PC1 receives data, does it give the data to the TCP IP software or the NetWare client software Of course, that depends on what is inside the data field. If the data came from the Novell server, then PC1 hands the data off to the NetWare client code. If the data comes...

Decimal Algorithm for Deriving the Broadcast Address No Subnetting or Basic Subnetting

The algorithms, both binary and decimal, for deriving the broadcast addresses are similar to the same algorithms for deriving the subnet numbers. The algorithms used for basic subnetting are used as a basis for the following algorithms for deriving the broadcast addresses. First, the decimal algorithm is as follows Step 1 Write down the IP address in decimal. Step 2 Copy below the IP address either the first one, two, or three dotted decimal numbers of the address, based on whether the subnet...

Decimal Algorithm for Deriving the Subnet Number Difficult Subnetting

The decimal algorithm that I like best for difficult subnetting works well. However, this algorithm is not very helpful for understanding subnetting. So, if you understand subnetting and are willing to use the more time-consuming binary algorithm on the exam for the difficult cases, you may want to skip this section to avoid getting confused. The algorithm is as follows Step 1 Write down the IP address in decimal. Step 2 Write down the mask in decimal. Step 3 Examine the mask. One of the four...

Decimal Algorithm for Deriving the Valid Subnets with Basic Subnetting

Time counts when taking the CCNA exam, so it's a good idea to take advantage of the easier decimal algorithms to derive facts about subnetting. The algorithm for deriving the subnet numbers of a network, given a static, basic mask, is extremely intuitive. Two cases for the decimal algorithm will be examined here a Class A network subnetted using mask 255.255.0.0, and a Class B network subnetted using mask 255.255.255.0 Step 1 Write down the 1 or 2 bytes of the network number. Step 2 Leave a...

Default Routes and the ip classless Command

Default route processing can be useful in several situations. Default route processing is a general term that refers to the choices that the router can make when no match exists between the routing table and the destination address of a packet. Without any default routes, a packet whose destination is not matched in the routing table is discarded. Figure 5-31 shows a typical case in which some form of default route would be useful. R1, R2, and R3 are connected to the rest of this network only...

Distance Vector Routing

CCNAs deal with routing problems on a daily basis some of these problems are a result of the logic behind distance vector routing protocols. To understand 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 Directly connected subnets are already...

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 four smaller four-question quizlets, which correspond to the four major headings in the Foundation Topics section of the chapter. Figure 3-1 outlines suggestions on how to spend...

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...

Fast Ethernet and Gigabit Ethernet

The two key additional features of Fast Ethernet, as compared to 10-Mbps Ethernet, are higher bandwidth and autonegotiation. Autonegotiation allows an Ethernet card, hub, or switch to determine which type of 100-Mbps Ethernet is supported by the device, hub, or switch on the other end of the cable. Also, support for half duplex or full duplex is negotiated. If the other device, such as a 10BaseT NIC, does not support autonegotiation, then autonegotiation will settle for half-duplex 10BaseT....

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 is needed because data is discarded when congestion occurs. A sender of data might be sending the data faster than the receiver can receive the data, so the receiver discards...

Flow Control Summary

One of Cisco's goals for CCNA and its other certifications is to ensure that passing means that you really understand the technology rather than simply understanding how to pass a particular exam. Focusing on understanding the concepts, as always, gives you a chance to get the exam questions correct. Table 3-6 summarizes the flow control terms and provides examples of each type. Memorizing these terms should help trigger your memory of flow-control concepts. Table 3-6 Flow-Control Methods...

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. Table...

Foundation Topics LAN Overview

Cisco expects CCNAs to be familiar with the three types of LANs Ethernet, Token Ring, and FDDI. There is a bias toward questions about Ethernet, which is reasonable given the installed base in the marketplace. For this reason, this chapter concentrates on Ethernet, with some comments on FDDI and Token Ring, as appropriate. Ethernet is best understood by considering the early 10Base5 and 10Base2 specifications. With these two specifications, a bus is shared among all devices on the Ethernet,...

Foundation Topics The IOS and Its User Interface

IOS, a registered trademark of Cisco Systems, is the name of the operating system found in most of Cisco's routers. The majority of Cisco routers run the IOS, with its familiar command-line interface (CLI). Also, some routing cards in other devices run IOS. For example, the Route Switch Module (RSM) card for the Catalyst 5000 series LAN switches performs routing functions and executes the IOS. Fixes and code updates to the IOS can include new features and functions. To learn more about the code...

Frame Relay Protocols

Che Carpe Montage Ligne

Frame Relay provides delivery of variable-sized data frames to multiple WAN-connected sites. Other than point-to-point links, Frame Relay is the WAN protocol most typically seen by CCNAs. This section reviews the details of how Frame Relay accomplishes its goal of delivery of frames to multiple WAN-connected sites. Frame Relay is a well-chosen name for reminding you that it most closely relates to OSI Layer 2. The term frame is generally associated with a collection of data bits that includes...

Given a Network Number and a Static Subnet Mask What Are the Valid Subnet Numbers

One of the reasons you find so many different slants on IP addressing in this chapter is that the CCNA exam questions you about IP in many different ways. The question in the heading of this section is unlikely to be the exact question, however. You should expect to see something like, Which of the following are valid subnets of network X, using mask Y , followed by the suggested answers. If you can figure out all the subnets of that network, you should be able to answer the multiple-choice...

H gri

After the IP packet is created, routing logic is repeated by Router A, this time for the new IP packet. Router A routes the IP packet based on the IP routing table, as does Router B and then Router C. Routers B and C have no knowledge that there is an IPX packet inside the IP packet. When the packet arrives at Router D, D notices that the destination address is one of its own addresses, so it examines the data further. Upon finding the encapsulation protocol header immediately after the IP...

How Error Recovery Is Accomplished

Regardless of which protocol specification performs the error recovery, all work in basically the same way. Generically, the transmitted data is labeled or numbered. After receipt, the receiver signals back to the sender that the data was received, using the same label or number to identify the data. Figure 3-7 summarizes the operation. As Figure 3-7 illustrates, the data is numbered, as shown with the numbers 1, 2, and 3. These numbers are placed into the header used by that particular...

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 6-1 to guide you to the next step.

Lx

Example 4-8 Single-Switch VLAN Configuration Matching Figure 4-28 switch(config) vtp transparent domain dummy switch(config) vlan 2 name VLAN2 switch(config) vtp transparent domain dummy switch(config) vlan 2 name VLAN2 Notice that some configuration seems to be missing. VLAN 1, with name VLAN1, is not configured because it is configured automatically. In fact, the name cannot be changed. Also, any ports without a specific static VLAN configuration are considered to be in VLAN1. Also, the IP...

Integrated Routing Protocols

So far, all the routing protocol functions discussed in this book fall under the classification of separate multiprotocol routing. To fully compare and contrast the meaning of this term with the alternative methods of integrated multiprotocol routing, a review of multiprotocol routing is in order. Consider Figure 6-18, which should remind you of one such concept. As discussed in Chapter 3, the router determines what type of Layer 3 packet is inside the received frame. There is a separate...

Interactions Between Adjacent Layers on the Same Computer

To provide services to the next higher layer, a layer must know about the standard interfaces defined between layers. These interfaces include definitions of what Layer N+1 must provide to Layer N to get services, as well as what information Layer N must provide back to Layer N+1. Figure 3-2 presents a graphical representation of two computers and provides an excellent backdrop for a discussion of interactions between layers on the same computer. Figure 3-2 Example for Discussion of...

Interactions Between the Same Layers on Different Computers

Layer N must interact with Layer N on another computer to successfully implement its functions. For example, the transport layer (Layer 4) can send data, but if another computer does not acknowledge that the data was received, the sender will not know when to perform error recovery. Likewise, the sending computer encodes a destination network layer address (Layer 3) in the network layer header. If the intervening routers do not cooperate by performing their network layer tasks, the packet will...

Internal Networks and Encapsulation Types

Cisco requires that CCNAs understand encapsulation, particularly with IPX. It is always Cisco's desire that the professional certifications prove that the candidate knows how to make networks that work rather than to certify individuals who are willing to memorize just for the sake of passing the test. However, IPX encapsulation is one area in which memorization is important once the base concepts are understood. Table 5-32, later in this section, lists several terms you should remember....

IP Addressing with Frame Relay Subinterfaces

Frame Relay configuration can be accomplished with or without the use of subinterfaces. If subinterfaces are not used, then all router interfaces attached to this same Frame Relay cloud should be configured with IP addresses in the same subnet. In other words, treat the Frame Relay cloud as any other multiaccess medium (such as a LAN). However, Frame Relay configuration without subinterfaces introduces some routing protocol issues when there is not a full mesh of virtual circuits (VCs) between...

IP Grouping Concepts and Subnetting

Cisco requires that CCNAs exhibit a thorough understanding of IP subnetting. Almost every organization with a network uses IP, and almost every one of these organizations uses subnetting. Subnetting is simply the process of treating subdivisions of a single Class A, B, or C network as if it were a network itself. By doing so, a single Class A, B, or C network can be subdivided into many nonoverlapping subnets. The needs for subnetting are both technical and administrative, as documented in the...

IPX Addressing and Routing

Cisco requires a thorough knowledge of two protocol stacks for the CCNA exam TCP IP and Novell NetWare. Novell's NetWare protocol stack defines Internetwork Packet Exchange (IPX) as a network layer equivalent protocol, as seen in Figure 5-32. IPX will be the focus of this initial section. IPX defines the 80-bit address structure, which uses a 32-bit network part and a 48-bit node part. As with IP and AppleTalk, all interfaces attached to the same data link use addresses in the same network....

IPX Configuration

Table 5-34 IPX and IPX RIP Configuration Commands Table 5-34 IPX and IPX RIP Configuration Commands ipx network network encapsulation type Interface mode Gives detailed view of IPX parameter settings, Shows entire routing table, or one entry if debug ipx routing events 1 activity Gives messages describing each routing update Gives messages describing each SAP update Sends IPX packets to verify connectivity The first sample is a basic configuration for the network in Figure 5-37. Example 5-18,...

Ive Taken ICNDNow What

For starters, you've taken the best path to prepare yourself. But let me temper that with the fact that if you retain more than 50 percent of what you heard in class, then you are an extraordinary person That said, you need the following three strategies Strategy 1 Use this book exactly as described in the opening pages of Chapters 2 through 8, respectively. Each of the foundational chapters begins with a quiz that helps you assess what you need to study. It then directs you to the appropriate...

Ive Taken ICRCNow What

The current version of the exam more closely matches the ICND class. However, if you compared the two course books, you would find much more in common than is different. In fact, more than half of ICND is directly taken from the ICRC course. Of course, if you retain more than 50 percent of what you heard in class, then you are an extraordinary person, so you probably still need to fill in some holes in your knowledge base. For you, the following strategies will be most helpful Strategy 1 Begin...

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, 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 over...

LAN Addressing

As a CCNA, you'll be expected to confidently understand and interpret LAN addresses. One important function of MAC addresses is to identify or address the LAN interface cards on Ethernet, Token Ring, and FDDI LANs. 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...

How to Use This Book to Pass the Exam

One way to use this book is to start at the beginning and read it cover to cover. Although that certainly would help you prepare, most people would not take that much time, particularly if you already knew a lot about some of the topics in the book. The rest of you might want to consider a different strategy on how to best use this book, depending on what training you have had. This book is designed to help you get the most out of the time you take to study. The core material for the CCNA is...

Masks and IP Address Formats

One common task that CCNAs run into is the interpretation of a network or subnet mask. This mask is used for several purposes. One key purpose is to define the number of host bits in an address. This mask also is used by computers when calculating the network or subnet number of which that address is a member. To fully appreciate what the mask is used for, you must understand the format of an IP address. Consider Figure 5-18, which shows the format of Class A, B, and C addresses when no...

OSI Data Link Layer Functions

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. Chapter 4, Bridges Switches and LAN Design, and Chapter 8, WAN Protocols and Design, provide more details about particular data link protocols, as well as their configuration in the IOS. This section examines four different protocols Ethernet, Token Ring, HDLC, and Frame Relay. A generalized definition of the...

OSI Origin and Evolution

To pass the CCNA exam, you must be conversant in a protocol specification with which you are very unlikely to have any hands-on experience. The difficulty these days when using the OSI protocol specifications as a point of reference is that almost no one uses those specifications. You cannot typically walk down the hall and see a computer whose main, or even optional, networking protocols are defined by OSI. OSI is the Open Systems Interconnection reference model for communications. OSI is a...

OSI Reference Model Layered Communication

In years past, the need to understand the Open Systems Interconnection (OSI) reference model for networking grew rapidly. The U.S. government passed laws requiring vendors to support OSI software on their systems, or 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 than predicted. Few vendors push...

Password Recovery

Several additional concepts related to loading the IOS must be understood before password recovery can be performed. First, software called the ROM monitor (rommon) is held in ROM on all routers and actually provides the code that is first used to boot each router. rommon has a rudimentary command structure that is used as part of the password recovery process. A limited-function IOS is also held in either ROM or in additional Flash memory called bootflash in either case, the IOS in bootflash...

Qa

As mentioned in Chapter 1, All About the Cisco Certified Network Associate Certification, the questions and scenarios in this book are more difficult than what you should experience on the actual exam. The questions do not attempt to cover more breadth or depth than the exam however, they are designed to make sure that you know the answer. Rather than allowing you to derive the answer from clues hidden inside the question itself, the questions challenge your understanding and recall of the...

RIP Version

RIP Version 2, defined by RFC 1723, is simply an improved version of RIP Version 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 holddown timers and route poisoning. Several features have been added, as listed in Table 6-14. This feature allows VLSM by passing the mask along with each route so that the subnet is exactly defined. Both clear text (RFC-defined) and MD5 encryption (Cisco- added feature) can be used to...

Scenario 22 Answers

The answers to the questions in Scenario 2-2 are as follows 1 The first boot system statement would be used boot system tftp c2500-js-113.bin 134.141.88.3. 2 The boot system flash command would be used. The TFTP boot would presumably fail because there is not currently a route to the subnet of which the TFTP server is a part. It is reasonable to assume that a route would not be learned 2 minutes later when the router had reloaded. So, the next boot system command (flash) would be used. 3 The...

Scenario 51 IP Addressing and Subnet Calculation

No one trusts you yet, so they will not give you any passwords to the router. Your mentor at your new company has left you at his desk while he goes to a meeting. He has left a Telnet window up, logged in to one router in user mode. In other words, you can issue only user mode commands. Assuming that you had issued the following commands (see Example 5-28), draw the most specific network diagram that you can. Write the subnet numbers used on each link onto...

Scenario 71 IP Filtering Sample

Scenarios 7-1 through 7-3 all use Figure 7-13, each with a different set of requirements for filtering. In each case, configure a correct access list for the routers and enable the access list. Place the access list in the router that filters the unneeded packets as quickly as possible that is, before the packets have been sent far away from the originator. Figure 7-13 Network Diagram for IP Filtering Scenarios 7-1, 7-2, and 7-3

Scenario 74 IPX Filtering

IPX packet and SAP filtering concepts and configuration are reviewed in this scenario. Sample configurations are supplied first. Your job is to interpret the current access lists and then create new packet access lists and SAP access lists to meet some additional criteria. The details are listed after Figure 7-14 and Examples 7-17 through 7-20. Figure 7-14 Network Diagram for Scenario 7-4

Scenarios Scenario

Given the network in Figure 3-22 and the address table in Table 3-20, perform the tasks that follow. This scenario uses an imaginary Layer 3 addressing structure as a method to review concepts. When in doubt, concentrate on the concepts. Also, the imaginary Layer 3 used in this example is here only to allow you to concentrate on the concepts instead of a particular protocol there is no need to memorize this scheme or expect questions like this on the exam. Figure 3-22 Musketeer Network for...

Service Advertisement Protocol

Service Advertisement Protocol (SAP) is one of the more important parts of the NetWare protocol specification, but it is also one of the biggest challenges when trying to scale an IPX network. SAP is used by servers to propagate information that describes their services. CCNAs are expected to be very familiar with SAP and the routers' roles in forwarding SAP information. The SAP process works very much like the process used by a distance vector routing protocol. In fact, SAP uses a concept...

Split Horizon and Infinity

Figure 6-10 Split Horizon and Infinite Distance Routes Example 6-3 RIP Configuration and Debugs on Albuquerque interface ethernet 0 ip addr 10.1.1.251 255.255.255.0 interface serial 0 ip addr 10.1.4.251 255.255.255.0 interface serial 1 ip addr 10.1.6.251 255.255.255.0 RIP received v1 update from 10.1.6.253 on Serial1 10.1.3.0 in 1 hops 10.1.2.0 in 2 hops 10.1.5.0 in 1 hops RIP received v1 update from 10.1.6.253 on Serial1 10.1.3.0 in 1 hops 10.1.2.0 in 2 hops 10.1.5.0 in 1 hops RIP received v1...

The Story of Ted and Ting

Ted and Ting both work for the same company at a facility in Snellville, Georgia. They work in the same department their job is to make lots of widgets. (Widgets are imaginary products the term widget is used in the United States often to represent a product when the actual product is not the topic of discussion.) Ted worked quickly and was a hard worker. In fact, because he was a very intense person, Ted tended to make more widgets than anyone else in Snellville, including Ting. Ted also liked...

Transparent Bridging

Transparent bridging is called transparent because the endpoint devices do not need to know that the bridge(s) exists. In other words, the computers attached to the LAN do not behave any differently in the presence or absence of transparent bridges. Transparent bridging is the process of forwarding frames, when appropriate. To accomplish this, transparent bridges perform three key functions Learning MAC addresses by examining the source MAC addresses of each frame received by the bridge...

Upgrading an IOS Image into Flash Memory

As Figure 2-11 illustrates, to upgrade an IOS image into Flash memory, you first must obtain the IOS image from Cisco. Then, you must place the IOS image into the default directory of a TFTP server. Finally, you must issue the copy command from the router, copying the file into Flash memory. Figure 2-11 Complete IOS Upgrade Process Example 2-5 provides an example of the final step, copying the IOS image into Flash memory. Example 2-5 copy tftp flash Command Copies the IOS Image to Flash Memory...

Viewing the Configuration and Old Style Configuration Commands

Once upon a time, commands that were used to move configuration files among RAM, NVRAM, and TFTP did not use easy-to-recall parameters such as startup-config and running-config. In fact, most people could not remember the commands or got the different ones confused. Figure 2-9 shows both the old and new commands used to view configurations. Figure 2-9 Configuration show Commands Figure 2-9 Configuration show Commands

Virtual LANs

A virtual LAN (VLAN) is a broadcast domain created by one or more switches. (Cisco expects CCNAs to have a solid command of VLAN concepts.) The VLAN is created via configuration in the switch, or possibly configuration referred to by the switch but residing in some external server (for example, using VLAN Membership Policy Server VMPS ). If a design calls for three separate broadcast domains, three switches could be used one for each broadcast domain. Each switch would also be connected to a...

Im New to Internetworking with Cisco and I Will Not Be Taking the ICND Course Now What

You can pass the CCNA exam without taking any courses. Of course, Cisco wants you to take the recommended courses for all the exams its motivation is not to make more money, because Cisco does not actually deliver the training the training partners do. Instead, Cisco truly believes that the more people understand its products, ultimately the happier its customers will be and the more products Cisco will sell. Cisco also believes that the official training is the right way to teach people about...

Conclusion

The CCNA certification is arguably the most important Cisco certification. It certainly is the most popular, is required for several other certifications, and is the first step in distinguishing yourself as someone who has proven knowledge of Cisco. The CCNA Exam 604-507 Certification Guide is designed to help you attain CCNA certification. This is the CCNA certification book from the only Cisco-authorized publisher. We at Cisco Press believe that this book certainly can help you achieve CCNA...

Introduction Overview of Certification and How to Succeed

Tree Life With Genome Size

Professional certifications have been an important part of the computing industry for many years and will continue to become more important. Many reasons exist for these certifications, but the most popularly cited reason is that of credibility. All other considerations held equal, the certified employee consultant job candidate is considered more valuable than one who is not. The most important and somewhat obvious objective of this book is to help you pass the CCNA exam (640-507). In fact, if...

Overview of Cisco Certifications

Cisco's main motivation behind the current certification program is to provide a means of measuring the skills of people working for Cisco Resellers and Certified Partners. Cisco fulfills only a small portion of its orders via direct sale from Cisco most times, a Cisco reseller is involved. Also, Cisco has not attempted to become the primary source for consulting and implementation services for network deployment using Cisco products instead, the company prefers to use partners as much as...

IP Configuration

Configuration of TCP IP in a Cisco router is straightforward. Table 5-27 and Table 5-28 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 Installing Cisco Network Devices is an excellent reference, particularly if you are not able to attend the instructor-led version...

Building an Initial Spanning Tree

Each bridge begins by claiming to be the root bridge. The Spanning-Tree Protocol defines messages used to exchange information with other bridges. These messages are called Configuration Bridge Protocol Data Units (CBPDUs). Each bridge begins by sending a CBPDU stating the following The root bridge's bridge ID. This is typically a MAC address on one of the bridge's interfaces. Each bridge sets this value to its own bridge ID. An administratively set priority. The cost between the bridge sending...

Scenario 54 IPX Examination

Given the network in Figure 5-46 and the command output in Example 5-29, Example 5-30, and Example 5-31, answer the questions and perform the tasks listed after Example 5-31. Figure 5-46 Scenario 5-4 Network Diagram Example 5-29 Albuquerque Command Output, Scenario 5-4 Albuquerque show ipx interface brief Albuquerque show cdp neighbor detail Example 5-29 Albuquerque Command Output, Scenario 5-4 (Continued) Platform cisco 2500, Capabilities Router Interface Serial0, Port ID (outgoing port)...

Network Protocols

TCP IP is the most important protocol covered on the CCNA exam and is the protocol used most often in networks today. This chapter covers the TCP IP protocols as well as IP addressing and subnetting. Cisco expects CCNAs not just to know IP addressing and routing, but also to know the concepts behind many other TCP IP protocols. In addition, CCNAs should be able to easily recall the commands used to examine the details of IP processing in a router. Of course, Cisco also requires you to...

Destination Unreachable ICMP Message

The five separate unreachable functions (codes) are accomplished using this single ICMP unreachable message. All five code types pertain directly to some IP, TCP, or UDP feature and are better described by using Figure 5-13 as an example network. Assume that Fred is trying to connect to the Web server, which uses TCP as the transport layer protocol. Three of the ICMP unreachable codes would possibly be used by Routers A and B. The other two codes would be used by the Web server. These ICMP...

Given a Network Number and a Static Subnet Mask How Many Hosts per Subnet and How Many Subnets

Finally, one more way the exam is likely to test your knowledge of IP addressing and subnetting is to ask which subnet masks will meet a set of requirements. This last type of question would be phrased as something like, If you need at least 30 hosts in each subnet and only 4 subnets, and if you are using network 192.1.1.0, which of the following masks meet your requirements To answer these types of questions confidently, you must have a good understanding of the three parts of an IP address....

Table of Contents

Chapter 1 All About the Cisco Certified Network Associate Certification 2 How This Book Can Help You Prepare and Pass the CCNA Exam 4 Overview of Cisco Certifications 4 Exams Required for Certification 6 Other Cisco Certifications 7 Recommended Training Path for CCNA 11 How to Use This Book to Pass the Exam 12 I've Taken ICND Now What 14 I've Taken ICRC Now What 15 I've Taken the Cisco Networking Academy Courses Now What 16 I'm New to Internetworking with Cisco, and I Will Not Be Taking the...

IP Naming Commands and Telnet

Names are never important to the process of routing IP packets. However, most human users prefer to use names instead of IP addresses, for obvious reasons. So, the process of using names and, most frequently, using a Domain Name System (DNS) to identify the IP address that corresponds to a name is important for end users. Router and switch administrators like to use names in many cases, for the same reason that end users like to use names. When the administrator uses a PC or workstation, that...

Ive Learned a Lot About CCNA Topics Through Experience But I Will Not Be Taking the ICND Course Now What

If you feel that you know a fair amount about CCNA topics already but are worried about the topics you simply just have not worked with, then this strategy is for you. This book is designed to help you figure out what CCNA topics you need some help with and then help you learn about them. Here's the simple strategy for you Strategy 1 Use this book exactly as described in the opening pages of Chapters 2 through 8. Each of the foundational chapters begins with a quiz that helps you assess what...

Whats on the CCNA Exam

Every test-taker would like to know exactly what is on the CCNA exam, as well as the other Cisco certification exams. Well, to be honest, exactly what is on the exam is a very closely guarded secret. Only those who write the questions for Cisco, and who have access to the entire question database, truly know what is really on the exam. Cisco makes fairly general CCNA exam content available to the public at the Web site In fact, two direct quotes from this Web site sumarize the exam CCNA...

How This Book Can Help You Prepare and Pass the CCNA Exam

The first goal for this book came at the request of the Cisco Career Certifications team they asked that we build a book that didn't just help you pass a test, but also for a book that helped you really understand the concepts and implementation details. (Because Cisco Press is the only Cisco authorized publisher, we tend to listen to Cisco ) A second goal was to make the content of the book the most comprehensive coverage of CCNA-related topics available, but without a lot of coverage of...

All About the Cisco Certified Network Associate Certification

Congratulations You have made your first step in beginning your journey to joining the Cisco Career Certifications group of certified professionals. CCNA is the first step into your journey. The Cisco Certified Network Associate (CCNA) certification is the most popular certification among all Cisco certifications. CCNA certification is a prerequisite for several other Cisco Certifications, which of course adds to its popularity. The exam itself is a computer-based exam, with multiple choice,...

ICMP Echo Request and Echo Reply

The ICMP Echo and Echo Reply messages are sent and received by the ping command. In fact, when people say that they sent a ping packet, they really mean that they sent an ICMP Echo Request. These two messages are very much self-explanatory. The Echo Request simply means that the host to which it is addressed should reply to the packet. The Echo Reply is the ICMP message type that should be used in the reply. The Request includes some data, which can be specified by the ping command whatever...

The TCPIP and Net Ware Protocols

Two of the most pervasively deployed protocols are TCP IP and Novell NetWare these also are the two key protocol architectures covered on the CCNA exam. TCP IP and NetWare are covered in much more detail in the upcoming chapters. This short section compares TCP IP, Novell, and OSI. The goal is to provide some insight into what some popularly used terminology really means. In particular, routing is defined as a Layer 3 process this section reviews how that term relates to TCP IP and NetWare. For...

Network Address Translation

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 may 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 address in some...

Ipx Rip Sap and GNS

The CCNA exam requires you not only to know the differences between IPX RIP and IP RIP, but to also know two other NetWare protocols used by the router Service Advertisement Protocol (SAP) and Get Nearest Server (GNS). Because IPX RIP and IP RIP were originally based on the same protocol (XNS RIP), the two are very similar. SAP and GNS have no equivalent feature in TCP IP. RIP for IPX works in a similar manner to IP RIP. The most obvious difference is that IPX RIP advertises IPX network...

Filtering IPX Traffic and SAPs

IPX access lists can be used to filter IPX packets sent by clients and servers, just as IP access lists are used to filter IP packets. However, similar functions can be performed by using Service Advertising Protocol (SAP) filters, which filter SAP updates sent by servers and routers. SAP filters are more common because they can be used to prevent clients and servers from trying to send packets, as well as to reduce the overhead of SAP updates. CCNAs deal with SAPs and SAP filtering on a...

Router Components

Before examining the IOS, a review of hardware and hardware terminology is useful. In addition to handling the logic of routing packets, the IOS controls the use of different physical components, which includes memory, processor, and interfaces. This section of the book reviews common hardware details. All Cisco routers have a console port, and most have an auxiliary port. The console port is intended for local administrative access from an ASCII terminal or a computer using a terminal...

Auto Summary and Route Aggregation

The IOS is optimized to perform routing as fast as possible. Most of the Layer 3 routing performance improvement in the brief history of routers has been through improved algorithms many times those improved algorithms later have been implemented in hardware to provide additional latency improvements. Although these improvements have been a great benefit, it is typically true that any algorithm that searches a list will run more quickly if the list is short, compared to searching a similar list...

RIP1 and IGRPNo Subnet Masks

RIP-1 and IGRP do not transmit the subnet mask in the routing updates, as seen in the debug output examples in this section. As a CCNA, Cisco expects you to be able to articulate the implications of the missing mask to the function of the routing protocol. Several subtle actions are taken in light of the lack of mask information in the update Updates sent out an interface in network X, when containing routes about subnets of network X, contain the subnet numbers of the subnets of network X but...