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112 - 238 CCNA 2: Routers and Routing Basics v3.1 Instructor Guide – Module 10

Copyright

©

2004, Cisco Systems, Inc.

10.1 TCP Operation

Essential Labs:

10.1.6

Optional Labs:

None

Core TIs:

10.1.6

Optional TIs:

10.1.1 – 10.1.5, and 10.1.7

Course-Level Claim:

Students can describe the operation of the major transport layer

protocols and the interaction and transportation of application layer data.

Certification-Level Claim:

Students can evaluate the TCP/IP communication process and its

associated protocols.

Hands-on skills:

none

10.1.1 TCP operation

IP addresses allow for the routing of packets within and between networks. However, it makes
no guarantee about delivery. The transport layer is responsible for the reliability of data flow.
This is accomplished through the use of sliding windows and sequencing numbers along with
a synchronization process that ensures communication. Have the students come up with an
analogy. One excellent example is a student who studies a foreign language for one year,
visits the country where the language is used, and asks everyone to repeat their words for
reliability and speak slowly for flow control.

10.1.2 Synchronization or three-way handshake

TCP is connection-oriented. Prior to data transmission two hosts go through a synchronization
process to establish a virtual connection. This process ensures that both sides are ready for
data and allows for the devices to determine the initial sequence numbers. This process is a
three-way handshake. Sequence numbers (SYN) and the role they play will be discussed in
detail in a later section. At this point it is important for students to understand that sequence
numbers are used to initiate communication between two devices. The sequence numbers
give each host a way to acknowledge the SYN bits so that the receiver knows the sender
responds to the proper connection request. This is done with bits in the TCP header. These
bits are called flags. The two flags involved are Sequence numbers (SYN) and Acknowledge
numbers (ACK). These flags are used to synchronize the SYN and ACK numbers between the
hosts. This will initialize the new session.

The three-way handshake is a three-step process that establishes the virtual connection
between two devices:

1. The source host initiates a connection. The host sends a packet with the SYN bit set

and indicates an initial sequence number of x with a bit in the header set to indicate a
connection request.

2. The destination host receives the packet, records the sequence number of x, replies

with an acknowledgment of x + 1, and includes its own initial sequence number of y. It
also sets the SYN bit to indicate the start of the return conversation.

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Содержание CCNA 2

Страница 1: ... Cisco Systems Inc Permission is granted to print and copy this document for noncommercial distribution and exclusive use by instructors in the CCNA 2 Routers and Routing Basics course as part of an official Cisco Networking Academy Program ...

Страница 2: ...skills based learning Global community of educators Student Centered Instructor Facilitated The CCNA curriculum has not been designed as a standalone e learning or distance learning course The teaching and learning model of the Cisco Networking Academy Program is based on instructor facilitation The Learner Model Academy Student diagram shows the emphasis that WWE puts on the learner The model beg...

Страница 3: ... with the realities of the local student to equipment ratio and time schedule This Guide can be used to facilitate the preparation of lesson plans and presentations Instructors are encouraged to research and use external sources to develop additional labs and exercises Core TIs have been highlighted for emphasis to assist the instructor in course and lesson planning These are not the only TIs that...

Страница 4: ...ugh other forums WWE is committed to the improvement of the curriculum assessment model and instructional resources such as this guide Please submit any feedback through CAC Check CAC for new releases of instructional materials Guide Overview Section II provides a scope and sequence overview of the course Section III summarizes the most important learning objectives target indicators and labs and ...

Страница 5: ... is the second of four CCNA courses that lead to the Cisco Certified Network Associate CCNA designation CCNA 2 focuses on initial router configuration Cisco IOS Software management routing protocol configuration TCP IP and access control lists ACLs Students will learn how to configure a router manage Cisco IOS software configure routing protocols on routers and set access lists to control access t...

Страница 6: ...cademy Connection Certification Alignment The curriculum is aligned with the following Cisco Internet Learning Solution Group ILSG courses CCNA Cisco Certified Network Associate INTRO Introduction to Cisco Networking Technologies The Course 2 claims state that students will be able to complete the following tasks Identify the key characteristics of common wide area network WAN configurations and t...

Страница 7: ...types and format of associated error and control messages Identify configure and verify the use of static and default routes Evaluate the characteristics of routing protocols Identify analyze and show how to rectify inherent problems associated with distance vector routing protocols Configure verify analyze and troubleshoot simple distance vector routing protocols Use commands incorporated within ...

Страница 8: ...on router configuration early in semester More efficient presentation and practice of IOS IGRP moved from CCNA 3 to CCNA 2 Access lists moved from CCNA 3 to CCNA 2 Revisions to TCP IP coverage More focus on routing tables Case study is required with format and timing determined by the Local Academy More interactive flash activities Sequence of over 40 e Labs Lab focus on two router labs ...

Страница 9: ...hould know and be able to do These claims are measured through certification exams Course A subset of a curriculum which is a collection of chapters to be offered as a scheduled course Course level claims Medium level statements about what a person who completes the CCNA 2 course should know and be able to do Core TI The TIs that apply most directly to the claims and learning objectives Instructor...

Страница 10: ...hasize the role of the instructor Learning objectives emphasize the role of the students Module caution Suggestions related to areas where difficulties may be encountered These are especially important for syllabus development lesson planning and pacing Optional lab A lab that is for practice enrichment or differentiation Essential lab A lab that is fundamental to the course Reusable Learning Obje...

Страница 11: ...s important to teach students the fundamental basics of WANs and roles that routers play in the WAN connection Inform the students that the serial interfaces will be used to simulate the DCE to DTE WAN connection Do not spend too much time on this module Students who complete this module should be able to Identify organizations responsible for WAN standards Explain the difference between WANs and ...

Страница 12: ...vices in a single building or several buildings that are located next to each other and WANs connect large geographic areas LANs connect devices and WANs connect data connections across a broad geographic area WANs operate at the physical and data link layers of the OSI model Devices used in a WAN are routers switches modems and communication servers The following topics are relevant to this TI Di...

Страница 13: ...at routers have both LAN and WAN interfaces Students should be able to identify the differences The two main functions of a router are to select the best path and to forward packets to the correct outgoing interfaces Networking models are useful because they facilitate modularity flexibility and adaptability Like the OSI model the three layer design model is an abstract picture of a network Models...

Страница 14: ...the technologies used Many of these topics will be covered in CCNA 4 and students should be encouraged to do additional research on one of these technologies and present it to the class 1 1 5 Academy approach to hands on labs In the Networking Academy lab all the networks are connected with a serial or Ethernet cable This allows the students to see and touch all of the equipment In a real network ...

Страница 15: ...functionality Hands on skills none 1 2 1 Introduction to WANs This section overviews the physical aspect of a router The physical layer is always studied first in networking topics The student will be able to identify internal components of the router and describe their functions describe the physical characteristics of the router identify common ports on a router and properly connect FastEthernet...

Страница 16: ...connections The management ports are asynchronous serial ports They are the console port and the auxiliary port Not all routers have an auxiliary port These serial ports are not designed as networking ports To prepare for initial startup and configuration attach an RS 232 ASCII terminal or a computer that emulates an ACSII terminal to the system console port It is essential for students to underst...

Страница 17: ...f WAN interface such as ISDN damage can occur The students should be taught to be observant and careful whenever connections are made Ask students the following questions What type of cable is used to connect from the router Ethernet interface to a hub or switch What type of cable is used to connect from the router Ethernet interface to a router Ethernet interface 1 2 7 Connecting WAN interfaces T...

Страница 18: ...er introducing formative assessments where the instructor supervises the students as they work on the router setup The use of formative assessments can be very valuable while students work through this router intensive and IOS intensive course Students should understand the following main points WAN and LAN concepts Role of a router in WANs and LANs WAN protocols How to configure console connectio...

Страница 19: ...n the configuration file and the IOS It is also important for students to feel comfortable when they enter into and move around in the CLI Do not move too quickly through these labs If students are uncomfortable with the CLI they will have difficulties with more complex labs Students who complete this module should be able to perform the following tasks Describe the purpose of the IOS Describe the...

Страница 20: ... on the show command in this TI A router and switch cannot function without an operating system Cisco IOS is the installed software in all Cisco routers and Catalyst switches A computer needs an operating system such as Windows or UNIX Discuss how the hardware cannot function without this software Make sure the students understand the role of the IOS 2 1 2 Router user interface Cisco IOS software ...

Страница 21: ...ng skills acquired on a specific device will apply to a variety of products The naming convention for the different Cisco IOS Releases contains three parts The platform on which the image runs The special capabilities and feature sets supported in the image Where the image runs and whether it has been zipped or compressed One of the major constraints for the use of a new IOS image is compatibility...

Страница 22: ...er initializes Bootstrap is loaded from ROM IOS is loaded from flash TFTP or ROM Config is loaded from NVRAM or TFTP into setup mode This section teaches students how to check the configuration during the boot process Setup mode is intended to quickly install a router with minimal configuration Discuss the initial startup of routers and explain why the IOS and configuration files can be loaded fro...

Страница 23: ... with the HyperTerminal program To configure a router a connection must be established between the PC and a router Make sure students understand that this is how routers need to be configured initially but it is not the only way to configure a router 2 2 5 Router login There are two levels of access to commands in a router User EXEC mode Privileged EXEC mode The user EXEC mode is a view only mode ...

Страница 24: ...ine Ctrl F moves forward one character Ctrl Z moves back out of configuration mode Esc and then B moves back one word Esc and then F moves forward one word The syntax of IOS commands can be complex Keyboard editing features can be used to correct text that has been entered When a router is being configured repetitive command statements typing errors that need to be fixed and commands that need to ...

Страница 25: ... retyping repeated commands 2 2 10 The show version command The show version command displays information about the Cisco IOS software version This information includes the system image file name and the location from which it was booted It also contains the configuration register and the boot field setting Explain that an important aspect of router and IOS maintenance is to know exactly which ver...

Страница 26: ... 2 exam Make sure students know how to access the command line prompt Formative assessments related to lab work are relevant to Module 2 Students should understand the following main points Understand the basic operation of IOS Identify various IOS features Identify methods to establish a CLI session with the router Use HyperTerminal to establish a CLI session Log into the router Use the help feat...

Страница 27: ...rated PDF files that should be the core of the learning experience Module 3 Caution Spend a lot of time on this module Students have wanted to program routers since the first day of CCNA 1 This module presents the core skills that the students will use to build all Cisco device configurations From this point in the CCNA 2 curriculum through the end of the CCNA 4 curriculum students may be deprived...

Страница 28: ...Routing Basics v3 1 Instructor Guide Module 3 Copyright 2004 Cisco Systems Inc Configure an interface description Configure a message of the day banner Configure host tables Understand the importance of backups and documentation ...

Страница 29: ...r login there is a choice of modes The modes interpret the commands that are typed and perform the operations There are two EXEC modes User EXEC mode Privileged EXEC mode The first configuration mode is referred to as global configuration mode or global config The following configuration modes are available in global configuration mode Interface Subinterface Controller Map list Map class Line Rout...

Страница 30: ... the system prompt If a router is not named then the system default will be Router Students need to understand that the name is an important part of the configuration process Much of the configuration and troubleshooting will be performed remotely Users will telnet into different routers For practice ask students to name the routers When instructors are asked to help troubleshoot a lab they can ea...

Страница 31: ...From each mode in the router the show command can be used to see all the available options Some of the show command options are as follows show interfaces show controllers serial show clock show hosts show users show history show flash show version show ARP show protocol show startup configuration show running configuration Students may want to use the show running config command as their primary ...

Страница 32: ...ment such as a CSU The curriculum shows the command entered as clock rate but on some Cisco routers the command can be entered as clockrate Both will result in the same running configuration The second item is that interfaces are shutdown by default and must be enabled with the no shutdown command The shutdown command will turn off an interface Instruct students to check for interfaces that are sh...

Страница 33: ...anges are completed Ask students the following questions Which command will erase the configuration file in NVRAM Which command will erase the configuration file in RAM Which command will copy the RAM to NVRAM Which command will copy the NRAM to RAM 3 1 7 Configuring an Ethernet interface An Ethernet interface can be configured from the console or a virtual terminal line By default interfaces are ...

Страница 34: ...In organizations where standards are treated seriously students need to understand that it is very important for the standards to be followed In organizations where there are no standards students can introduce standards to add value to the organization Students need to understand why standards are important and begin to apply them in the lab Encourage students to create and use standards Remember...

Страница 35: ...vironment with hundreds of routers thousands of interfaces and routers that are 1000 kilometers 621 4 miles away Tell the students that a customer from a branch office is unable to connect to headquarters Ask students how they can verify that the interface is connected to the correct branch office before they change anything on the interface There are several good answers such as ask the customer ...

Страница 36: ...he day MOTD A message of the day MOTD banner can be displayed on all connected terminals Students must enter global configuration mode to configure a message of the day banner They should use the banner motd command followed by a space and a delimiting character such as the pound sign Next students should add a message of the day followed by a space and the delimiting character again Instruct stud...

Страница 37: ...ter For example the startup configuration of a router can be stored in another place such as on a network server or on a TFTP server as a backup If the router goes down the stored file could be placed back on the router This would minimize the down time Configuration management is an important aspect of network management The backups of the configurations should be current and maintained in multip...

Страница 38: ...Copyright 2004 Cisco Systems Inc capturing text in the router If the file needs to be copied back to the router it can be pasted into the router Ask students the following questions What is the command used to copy RAM to NVRAM What is the command used to copy NVRAM to RAM ...

Страница 39: ...several modes User EXEC mode Privileged EXEC mode Global configuration mode Other configuration modes The CLI can be used to make changes to the configuration such as the following Set the hostname Set passwords Configure interfaces Modify configurations Show configurations Students should understand the following main points Configuration standards are important elements in the ability of any org...

Страница 40: ...s a remote connection utility that allows network administrators to perform configuration and management tasks on routers and switches Students will learn how to establish manage and terminate Telnet sessions with remote devices Students should already be familiar with basic router setup and configuration Students should possess basic router configuration skills and be able to physically connect t...

Страница 41: ...ts to a multicast address to collect information from its neighbors These advertisements are periodically repeated so that updated information can be gathered CDP advertisements are also used by the receiving devices to learn about the sender CDP information is dynamic It is constantly updated through periodic advertisements Reporting devices provide a Time to Live TTL value for the data CDP opera...

Страница 42: ... allows students to perform the associated Flash e Lab TLV Definition Device ID TLV Identifies the device name in the form of a character string Address TLV Contains a list of network address of both receiving and transmitting devices Port ID TLV Identifies the port on which the CDP packet is sent Capabilities TLV Describes the functional capabilities of a device in the form of a device type such ...

Страница 43: ... an interface clear cdp counters Resets the traffic counters to zero show cdp Displays the interval between transmissions of CDP advertisements the number of seconds the CDP advertisement is valid for a given port and the version of the advertisement show cdp entry entry name protocol version Displays information about a specific neighbor which can be limited to protocol or version information sho...

Страница 44: ... the device from advertising information about itself to outside devices CDP can be disabled at two levels The no cdp run command can be used in global configuration mode to disable CDP for the entire device This should be used when only one Cisco device is present and CDP would serve no purpose on the network segment CDP can be disabled for a specific interface The network administrator must be i...

Страница 45: ...n debug cdp packets Displays CDP packet related information cdp timers Specifies how often the Cisco IOS software sends CDP updates cdp holdtime Specifies the hold time to be sent in the CDP update packet show cdp Displays global CDP information such as timer and hold time information Review the following key points CDP is Cisco proprietary CDP runs on any SNAP enabled media CDP functions at Layer...

Страница 46: ...aneous Telnet connections Telnet also provides a tool for troubleshooting The establishment of a Telnet connection confirms the connectivity and functionality of the application layer The ping command only confirms Layer 3 connectivity 4 2 2 Establishing and verifying a Telnet connection From the router console Telnet can be used to connect to remote devices The administrator must type in the name...

Страница 47: ... of the router Example Denver disconnect paris The procedure for suspending a Telnet session is as follows Press Ctrl Shift 6 and then the letter X Enter the name of the router or IP address of the next connection Students often think that the Ctrl Shift 6 then X sequence will terminate a Telnet session They need to understand that this only suspends the session They also need to know how to resum...

Страница 48: ...ice executing the traceroute command sends out a sequence of User Datagram Protocol UDP datagrams each with incrementing Time To Live TTL values to an invalid port address Default 33434 at the remote host First three datagrams are sent each with a TTL field value set to 1 The TTL value of 1 causes the datagram to timeout as soon as it hits the first router in the path This router then responds wit...

Страница 49: ...ax 32 35 36 ms Demonstrate an unsuccessful ping LAB D ping lab c Type escape sequence to abort Sending 5 100 byte ICMP Echoes to 199 6 13 2 timeout is 2 seconds Success rate is 0 percent 0 5 Demonstrate a successful trace LAB A trace lab e Type escape sequence to abort Tracing the route to LAB E 210 93 105 2 1 LAB B 201 100 11 2 32 msec 24 msec 24 msec 2 LAB C 199 6 13 2 32 msec 52 msec 40 msec 3 ...

Страница 50: ...occur on IP networks Three commands can be used to perform troubleshooting telnet verifies the application layer software between the source and the destination This is the most complete test mechanism available ping uses the ICMP protocol to verify the hardware connection and the IP address of the network layer This is a very basic test mechanism traceroute is used to find failures in the path fr...

Страница 51: ...ured routers in a taped box with a console cable and a power strip cord coming out of it Mark the box with the name of a distant city Then ask the students to draw a topology map of the internetwork of that city Students should understand the following main points How to enable and disable CDP How to use the show cdp neighbors command How to determine which neighboring devices are connected to whi...

Страница 52: ... software source options Students will also learn how to use commands to load Cisco IOS software onto a router maintain backup files and upgrade Cisco IOS software Module Caution Make sure students fully understand how to copy and paste configurations into a router Make sure that they understand the importance of configuration management especially backups Students who complete this module should ...

Страница 53: ... executes The bootstrap basically indicates a starting point in memory that will load other instructions Now the router is ready to load the operating system which is Cisco IOS The IOS can be found in flash TFTP or ROM The boot field of the configuration register will indicate the location of the IOS image After the operating system is loaded and operational the configuration file from NVRAM is lo...

Страница 54: ...d from flash or the TFTP server a subset of the IOS can be loaded from ROM Make sure students understand that the IOS loaded from ROM is only a subset of the Cisco IOS software and might be an older version Use the boot system command to specify a fallback sequence and save it to NVRAM Restart the router and allow the students to verify the boot system locations during the next start up Explain wh...

Страница 55: ... impact that the boot sequence and the configuration register has on routing they must perform the hands on labs Make sure each student can complete and explain the labs Discuss the results and purpose of the labs after they have been completed by all of the students Instruct students to verify the configuration register setting on a regular basis Occasionally change the configuration register set...

Страница 56: ... a router Explain that the IFS is based on UNIX file systems 5 2 2 IOS naming convention Many different versions of the IOS are available The IOS supports many different hardware platforms and features This is a continuous development process To identify the different versions Cisco has a naming convention for the IOS files The IOS naming convention uses different fields in the name such as hardwa...

Страница 57: ...P server where the config file is located Enter the name of the config file or accept the default name Confirm the configuration filename and the server address Make sure students realize that there are other ways to back up a configuration file Other methods will be discussed in later sections It is important for students to understand this process and all the procedures that are explained It is ...

Страница 58: ...ter the word End At the end of each of the interface sections students should add no shutdown To save the clean version select File Save Before the configuration is restored any remaining configuration should be removed from the router by issuing the command erase startup configuration Use the reload command to restart the router HyperTerminal can be used to restore the configuration Enter global ...

Страница 59: ...now that the newer releases are larger and may require flash and RAM upgrades To ensure a successful transfer students can ping the TFTP server from the router to test reachability Stress that when students enter a path name or the name of the IOS the entry must be exact If it is not exact the procedure will not work One technique is to cut and paste the name of the file from a Windows Explorer di...

Страница 60: ... configuration To set a ROMmon environment variable the name is typed followed by an equal sign and the value for the variable All variable names are case sensitive The minimum variables required to use the tftpdnld command are as follows The IP address of the LAN The subnet mask The default gateway The IP address of the TFTP The IOS filename on the server Discuss these procedures with the student...

Страница 61: ...v3 1 Instructor Guide Module 5 Copyright 2004 Cisco Systems Inc Discuss the following alternatives with the students NVRAM TFTP server ROM Make sure the boot commands are reviewed Stress the importance of familiarity with the bootup procedures ...

Страница 62: ...xam Students should understand the following main points Identify stages of the router boot sequence Identify how the Cisco device locates and loads the Cisco IOS Identify the configuration register settings Identify the files used by the Cisco IOS and their functions Identify the locations on the router of the different file types Identify the parts of the IOS name Manage configuration files usin...

Страница 63: ...n contains fundamental terminology that instructors may need to get the students interested in learning about Make sure students understand this material so that static and dynamic routing can be compared in future lessons Students who complete this module should be able to perform the following tasks Explain the significance of static routing Configure static and default routes Verify and trouble...

Страница 64: ...c routing is used a network administrator must configure information about remote networks manually Any network topology changes require the network administrator to add and delete static routes to account for the changes Ask students the following questions What is the difference between static and dynamic routing When should a static route be used instead of a dynamic routing protocol 6 1 2 Stat...

Страница 65: ...re out what route the packet should take then this routing information must be very reliable Only directly connected routes have a default administrative distance that is trusted more The default administrative distance for directly connected devices is zero Administrative distance should not be confused with the metric of the route The metric of the route indicates the quality of a route When a r...

Страница 66: ...s optional 4 Repeat Step 3 for as many destination networks as were defined in Step 1 5 Exit global configuration mode 6 Save the active configuration to NVRAM by using the copy running config startup config command Here is an example of a route from Rt1 to network 192 168 2 0 Rt1 config terminal Enter configuration commands one per line End with CNTL Z Rt1 config ip route 192 168 2 0 255 255 255 ...

Страница 67: ...he outside networks or the IP address of the next hop router In most cases the IP address of the next hop router should be specified 3 Exit global configuration mode 4 Save the active configuration to NVRAM with the copy running config startup config command Here is an example for Rt1 Rt1 config terminal Enter configuration commands one per line End with CNTL Z Rt1 config ip route 0 0 0 0 0 0 0 0 ...

Страница 68: ... area N1 OSPF NSSA external type 1 N2 OSPF NSSA external type 2 E1 OSPF external type 1 E2 OSPF external type 2 E EGP i IS IS L1 IS IS level 1 L2 IS IS level 2 ia IS IS inter area candidate default U per user static route o ODR P periodic downloaded static route Gateway of last resort is not set C 192 168 0 0 24 is directly connected FastEthernet0 0 C 192 168 1 0 24 is directly connected Serial0 0...

Страница 69: ...eue 0 75 0 drops 5 minute input rate 0 bits sec 0 packets sec 5 minute output rate 0 bits sec 0 packets sec 194 packets input 12076 bytes 0 no buffer Received 194 broadcasts 0 runts 0 giants 0 throttles 0 input errors 0 CRC 0 frame 0 overrun 0 ignored 0 abort 194 packets output 12076 bytes 0 underruns 0 output errors 0 collisions 5 interface resets 0 output buffer failures 0 output buffers swapped...

Страница 70: ...eme The Internet Protocol IP is an example of a routed protocol Students should know the difference between a routed and routing protocol at the end of this TI Identify the location of each protocol in the OSI model Ask students the following questions TCP is at which layer IP is at which layer Is the protocol connection oriented or connectionless RIP IGRP EIGRP and OSPF are at which layer and wha...

Страница 71: ...s If all the routers needed to communicate with all other routers on the Internet each router would have a tremendous number of routes and would use large amounts of bandwidth to share the routes with the other routers This is referred to as overhead for the routers More overhead will increase hardware requirements When a network is divided into autonomous systems only the routers inside the local...

Страница 72: ...ree A routing table of paths and ports to each network A link state advertisement LSA which is a small packet sent between routers that contains link information Link state routing requires more memory Routers send updates when there is a change in the table There is less network traffic because the routers are not sending updates every 30 or 90 seconds The routers in an area elect a Designated Ro...

Страница 73: ...the information 6 3 2 Routing configuration Global and interface parameters must be set when an IP routing protocol is selected Global tasks include the selection of a routing protocol either RIP or IGRP and IP network numbers must be indicated It is important to check the interface IP address and subnet configuration A common problem is to assign the wrong IP address or subnet mask The network co...

Страница 74: ...n CCNA 2 will be IGPs The protocols RIP IGRP EIGRP and OSPF are all IGPs Exterior routing protocols are designed for use between two different autonomous systems An example of an EGP protocol is Border Gateway Protocol BGP BGP is the routing protocol used on the Internet Interior routing protocols are designed to be used within an autonomous system BGP is the routing protocol used on the Internet ...

Страница 75: ...to a destination network Network administrators must manually configure static routes Default routes are special static routes that provide routers with gateways of last resort Static and default routes are configured with the ip route command Static and default route configuration can be verified with the show ip route ping and traceroute commands How to verify and troubleshoot static and default...

Страница 76: ... plenty of time in the labs and to experiment with RIP Since the labs are complex students may require additional time which may affect the availability of lab equipment Provide guidance on how to follow an effective well documented and patient troubleshooting strategy since students may need to troubleshoot their labs If the lab IOS does not support IGRP instructors should use EIGRP and emphasize...

Страница 77: ... tables to continuously make good path determination decisions Periodically changes in a network will affect the decisions made by a router For example a router may be taken off line for upgrades or repairs or an interface on a router may go down If routers are not aware of the changes that have occurred in a network they may switch packets to interfaces that are no longer connected to the best ro...

Страница 78: ...ter C to B to A to D and back again to C Problem Routing Loops Convergence is when all routers have the same information about the network Convergence is a by product of the routing updates that are sent out based on the routing protocol used on a router If updated information does not reach all routers in a network quickly enough then incorrect routing information may be sent out by routers that ...

Страница 79: ...chnical example is a timed test If someone takes a timed test they have a predefined amount of time to complete it When the maximum amount of time has been reached the test ends even if some questions have not been answered 7 1 4 Eliminating routing loops through split horizon Another possible source for a routing loop occurs when incorrect information that has been sent back to a router contradic...

Страница 80: ...of another router Use the figure in this section for reference If Router 2 sends out an update to Router 1 about the status of Network A it cannot receive a report back from Router 1 about Network A From the description in the curriculum which is included above if split horizon were in use in Step 2 Router A would have ignored information about Network 1 from Router B More specifically Router B wo...

Страница 81: ...h indicates that Network X is now unreachable is quickly propagated through the network This speeds convergence and reduces the likelihood that a loop will develop 7 1 6 Avoiding routing loops with triggered updates Routing table updates are automatically sent out at specific time intervals by distance vector routing protocols As discussed earlier slow convergence can create a scenario in which ro...

Страница 82: ...mation while the holddown timer is still in effect Holddown timers are used to allow updates about bad routes to be propagated Routers that have already received the information will not accept update information about the bad route from neighbor routers that may not know that it is inaccessible Students may need some additional help with distance vector routing protocols Several of the topics wil...

Страница 83: ...ification of directly connected networks that will participate in the routing process When the basic configuration of RIP is complete regular updates are sent every 30 seconds and triggered updates are sent upon notification of metric changes The following is an example of RIP configuration BHM config router rip selects RIP as the routing protocol BHM config router network 1 0 0 0 specifies a dire...

Страница 84: ...uting loops The split horizon rule prevents information about a route from being sent out the same interface from which it was originally received Split horizon is used to avoid the creation of routing loops due to multiple routers that advertise routes to each other about the same network The no ip split horizon command can be used to disable split horizon Hold down timers are used to define the ...

Страница 85: ...include incorrect network statements discontiguous subnets and split horizons These RIP update issues can be identified with some basic show and debug commands The debug ip rip command enables rip debugging and will display all of the rip updates as they are sent and received The following is an example of the output of the debug ip rip command LAB A debug ip rip RIP protocol debugging is on LAB A...

Страница 86: ...on about the internal network to be sent out to other routers If Router Z is a stub network the administrator of Router A may prevent routing updates from being sent to Router Z since there is one way in and one way out Students must understand that routes will still be learned through this interface They also need to know that the network that this interface is connected to is advertised if a net...

Страница 87: ... the same path Students should be comfortable with the term round robin load balancing This means that packets will be equally shared between the equal paths This is done by alternating the packet output between the interfaces for each of the paths The students should also understand that this does not equally balance the traffic between the paths This is because the packets are of various sizes S...

Страница 88: ...the algorithm is changed MTU is only exchanged in the update It is not used in any calculation One additional item to note is that Cisco offers more support for EIGRP than IGRP Many of the newer releases of IOS do not support IGRP 7 3 2 IGRP metrics IGRP uses several metrics to calculate the overall routing metric of each route Bandwidth the lowest bandwidth value in a path Delay the cumulative in...

Страница 89: ...s If a router does not receive an update about a particular route it marks that route as possibly down Split horizons are designed to prevent routing loops with the rule that routing information is not sent back in the direction from which it was learned This prevents routing loops between adjacent routers Poison reverse updates are necessary to avoid larger routing loops An increase in metric may...

Страница 90: ...IP to IGRP With the creation of the IGRP in the early 80s Cisco Systems was the first company to solve the problems associated with RIP IGRP was designed to have a greater maximum hop count which gave it more scalability for larger companies IGRP uses multiple metrics to determine the best path bandwidth and delay as opposed to the hop count metric used by RIP As a result of these improvements IGR...

Страница 91: ...m number The following commands are used to troubleshoot IGRP show ip protocols show ip route debug ip igrp events debug ip igrp transactions ping trace Both the debug ip igrp events and debug ip igrp transactions commands can be used to verify that routing information is being passed between routers The ping command can be used to test network connectivity The trace command can be used to locate ...

Страница 92: ...ery Students should understand the following main points How routing information is maintained through distance vector protocols How routing loops occur in distance vector How to define a maximum to prevent count to infinity How to eliminate routing loops through split horizon Route poisoning How to avoid routing loops with triggered updates How to prevent routing loops with holddown timers How to...

Страница 93: ...92 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Module 7 Copyright 2004 Cisco Systems Inc How to migrate RIP to IGRP How to verify IGRP configuration How to troubleshoot IGRP ...

Страница 94: ...spect of TCP IP Make sure the students understand that ICMP is the protocol that handles these functions for the TCP IP suite If time is an issue this module can be used as a reference for other modules when students encounter different ICMP error messages in their labs and in their use of programs such as browsers and e mail Students who complete this module should be able to perform the followin...

Страница 95: ...et It uses the IP addressing scheme but has a different packet format than IP 8 1 2 Error reporting and error correction ICMP is an error reporting protocol for IP When datagram delivery errors occur ICMP is used to report these errors back to the sender of the datagram This is an excellent opportunity to show the students this procedure in the lab setup They should be shown that ICMP does not cor...

Страница 96: ...ng command is used Also point out that a way to check the function of DNS is to ping the same destination by domain name and by IP address If the remote location responds to the IP address but not to the domain name then this indicates a DNS issue Explain that a location may be unreachable because of security restrictions ICMP may be a blocked protocol 8 1 6 Detecting excessively long routes Situa...

Страница 97: ...8 1 8 Destination unreachable message Hardware failures improper protocol configuration disabled interfaces and incorrect routing information are some of the reasons for unsuccessful delivery of data Give the students examples similar to the figures in the curriculum Specify values and indicate the reason for each failure Explain that the students must understand the various causes of ICMP destina...

Страница 98: ...n or the existence of a better gateway to a remote network Like all ICMP messages ICMP control messages are encapsulated 8 2 2 ICMP redirect change requests An ICMP redirect change request can only be initiated by a gateway which is commonly used to describe a router All hosts that communicate with multiple IP networks must be configured with a default gateway This default gateway is the address o...

Страница 99: ...niversal Time The host that originated the ICMP timestamp request can use these timestamps to estimate transit time across the network The host can subtract the originate time from the transit time to guess the transit time However this can vary widely based on traffic and congestion The host that originated the ICMP timestamp request can also estimate the local time of the remote computer This is...

Страница 100: ...dentifies the default gateway for the local host 8 2 8 Congestion and flow control messages Congestion occurs when multiple computers try to access the same receiver or when traffic from a high speed LAN reaches a slower WAN connection The effect of congestion on a network is dropped packets that result in a loss of data To reduce data lost ICMP messages must be sent to the source of the congestio...

Страница 101: ...es to alert the sender that the data did not reach its destination ICMP echo request and echo reply messages allow the network administrator to test IP connectivity to aid in the troubleshooting process ICMP messages are transmitted with the IP protocol so their delivery is unreliable ICMP packets have their own special header information which starts with a type field and a code field Potential c...

Страница 102: ...e command to gather detailed information about the routes installed on the router Configure a default route or default network Understand how a router uses Layer 2 and Layer 3 addressing to move data through the network Use the ping command to perform basic network connectivity tests Use the telnet command to verify the application layer software between source and destination stations Troubleshoo...

Страница 103: ...aluable the show ip route command is to network troubleshooting Routes can be added to a router through two methods Static routing An administrator manually defines routes These routes do not change until a network administrator manually programs the changes Dynamic routing Routers follows rules defined by a routing protocol to exchange routing information These routes change automatically as neig...

Страница 104: ...one router to the next For a packet to get from the source to the destination both Layer 2 and Layer 3 addresses are used Explain how important this concept is for the students to understand The Layer 3 address is used to route a packet from the source network to the destination network The source and destination IP addresses remain the same The MAC address changes at each hop or router A data lin...

Страница 105: ...c on bandwidth delay load reliability ticks maximum transmission unit and cost Discuss with the students the differences between each of these metrics so they fully understand what is used to calculate the best route Each routing algorithm interprets what is best in its own way The algorithm generates a number called the metric value for each path through the network The smaller the metric value i...

Страница 106: ... students to look for simple solutions first when they test a network Some of the most common problems on IP network result from errors in the addressing scheme Reinforce how important IP addressing schemes are to a network Explain to students that a large part of their role in the workplace will require troubleshooting 9 2 2 Using a structured approach to troubleshooting Troubleshooting is a proc...

Страница 107: ...ts discuss possible Layer 1 problems Instruct students to check for the simplest of problems first such as power cords or electricity 9 2 5 Layer 3 troubleshooting using ping The ping utility is used to test network connectivity Echo protocols are used to test if protocol packets are being routed The ping command sends a packet to the destination host and then waits for a reply packet from that ho...

Страница 108: ... possibly the most important tool to discover Layer 1 and Layer 2 problems in the router The first parameter refers to the physical layer The second parameter indicates if the IOS processes that control the line protocol consider the interface to be usable This is determined by whether keepalives are successfully received If the interface misses three consecutive keepalives the line protocol is ma...

Страница 109: ...and subnetworks and how that information was learned If the output of the show ip route command does not show the expected learned routes then it is possible that routing information is not being exchanged In this case use the show ip protocols command on the router to check for a possible misconfigured routing protocol The show ip protocols command output can be used to diagnose a multitude of ro...

Страница 110: ...CE cable 9 3 7 Introduction to debug The debug command is used to display dynamic data and events The debug command output gives more insight into the current events of the router The dynamic output of the debug command has a high performance cost It produces a high processor overhead that disrupts normal router operation Debug should be used conservatively Stress to the students that debug is a v...

Страница 111: ...ng Students should understand the following main points Use and understand the output of the show ip route command Determine the gateway of last resort Determine the route source and destination address Determine the route administrative distance Determine the route metric Determine the route next hop Determine the last route update Observe multiple paths to a destination Use a structured approach...

Страница 112: ... analyze the operation of TCP on live networks Module 10 Caution TCP was introduced in CCNA 1 but there is much more detail in this section Students need to understand TCP TCP ports and sessions are the foundations of network performance control and security This is very challenging material for students who are still trying to separate the functions of Layer 2 headers Layer 3 headers and Layer 4 ...

Страница 113: ... two hosts go through a synchronization process to establish a virtual connection This process ensures that both sides are ready for data and allows for the devices to determine the initial sequence numbers This process is a three way handshake Sequence numbers SYN and the role they play will be discussed in detail in a later section At this point it is important for students to understand that se...

Страница 114: ...tant concept for the students to understand to help prevent hackers from creating chaos in a network 10 1 4 Windowing and window size Data is often too large to be sent in a single data segment TCP breaks data into segments A good analogy is small children who cannot eat large pieces of food Their food must be cut into smaller pieces to be eaten Another way to explain the advantages of this segmen...

Страница 115: ...gain TCP uses expectational acknowledgments in which the acknowledgement number refers to next octet that is expected Windowing is also a flow control mechanism If there is a window size of three the source can send three octets to the destination It then waits for an acknowledgment When it is received another three octets are sent If the data is not received due to overflowing buffers no acknowle...

Страница 116: ...client cannot construct a packet that is destined for just the IP address of the server with TCP because both SMTP and WWW use TCP as their transport layer protocol A port number must be associated with the conversation to ensure that the packet reaches the appropriate service Port numbers are used to keep track of different conversations that cross the network at the same time Port numbers are ne...

Страница 117: ...termined dynamically A client usually determines the source port by randomly assigning a number above 1023 Clients and servers use ports to distinguish what process each segment is associated with This is an important concept for the students to understand about port numbers Explain that the server responds with the same port numbers except the source and destination port numbers are swapped For e...

Страница 118: ... the port number the street address would be the MAC address and the city and state would be the IP address Multiple letters can be mailed to the same MAC and IP address but different port numbers would be different family members living in the same household To better explain this the instructor may want to ask some questions and start a discussion Could a protocol be routable with only Layer 3 a...

Страница 119: ...z in the curriculum and the online Module 10 exam Students should understand the following main points TCP operation description Synchronization process or three way handshake Denial of service attacks Windowing and window size Sequencing numbers Positive acknowledgement and retransmission PAR UDP operation Multiple conversations between hosts Ports for services Ports for clients Port numbering an...

Страница 120: ...t or deny statements that apply to addresses or upper layer protocols Module Caution It may be difficult for students to understand the concept of ACLs This topic will require additional time for students to understand Work through numerous examples Have students finish the hands on labs and e Labs Consider spending less time on Modules 1 5 8 and 10 to make sure ACLs are properly learned Students ...

Страница 121: ...and destination address of the packets to apply the concept of an ACL Review the OSI model and the protocols at each layer with the students The reasons for ACLs and the methods that ACLs use to accomplish these functions may not be apparent to the students ACLs may require some time to grasp Do not rush through these sections Give the students enough time to absorb this information Encourage the ...

Страница 122: ...up command is issued in the interface configuration mode To assign an access list to an interface the direction of the traffic that the list will filter must also be defined Traffic that enters an interface is filtered with an inbound access list Traffic that leaves an interface is filtered with an outbound access list To alter an ACL that contains numbered ACL statements all the statements in the...

Страница 123: ...tatements from specific references such as individual hosts to general references such as entire networks when access list logic overlaps Do not work with an access list that is actively applied Use Notepad or a similar text editor to create comments that outline the logic and then fill in the statements that perform the logic Remember new lines are always added to the end of the access list Use t...

Страница 124: ...e if the subnet mask is 255 255 240 0 the following equation would be used 255 255 255 255 255 255 240 0 0 0 15 255 0 0 15 255 is the wildcard mask Emphasize the importance of assigning IP addresses within the subnetwork If addresses are logically assigned based on system use or location then an ACL can be created to permit or deny these hosts with a single statement These logical host IP address ...

Страница 125: ...s that are routed The comparison will result in either permit or deny access for an entire protocol suite based on the network subnet and host addresses The standard version of the access list global configuration command is used to define an IP standard ACL with a number in the range of 1 to 99 The full syntax of the standard ACL command is as follows Router config access list access list number ...

Страница 126: ...a DYNAMIC list of PERMITs or DENYs permit Specify packets to forward remark Access list entry comment The permit or deny is the same as the standard rt1 config access list 101 permit 0 255 An IP protocol number ahp Authentication Header Protocol eigrp Cisco s EIGRP routing protocol esp Encapsulation Security Payload gre Cisco s GRE tunneling icmp Internet Control Message Protocol igmp Internet Gat...

Страница 127: ...very type of traffic that is permissible requires a line in the list to permit it All other traffic will be denied by the implicit deny at the bottom of the list These lists consist of primarily permit statements and do not have a permit any at the end of the list While these lists require more planning and lines of code they are typically more secure The maintenance for this type of list is usual...

Страница 128: ... destination as possible For example a standard ACL should be placed on Fa0 0 of Router D to prevent traffic from Router A Administrators can only place access lists on devices that they control A standard ACL should be placed close to the destination First have the students decide which router is closest to the destination and then pick which interface is the closest to the destination An ACL can...

Страница 129: ... of ACL controls which users can telnet into a remote router To test this in the labs have students configure routers and telnet into a remote router to test connectivity Configure and apply the ACL to the vty lines to deny access Then test the Telnet again Here are the commands to configure virtual terminal access Rt1 config access list 2 permit 172 16 1 0 0 0 0 255 Rt1 config access list 2 permi...

Страница 130: ... implementation of security access procedures ACLs are used to control and manage traffic For some protocols two ACLs can be applied to an interface an inbound ACL and an outbound ACL After a packet is matched to an ACL statement it can be denied or permitted access to the router Wildcard mask bits use the number one 1 and the number zero 0 to identify how to treat the corresponding IP address bit...

Страница 131: ...os to make sure that all requirements are fulfilled Each scenario guides the student through the proper steps to ensure that the project is completed properly This case study requires the student to accomplish the following tasks Set up the physical layout of the network using the diagram and accompanying narrative Correctly configure the routers with a basic router configuration Set up a TFTP ser...

Страница 132: ...ly The few documents that existed were poorly written So during the weekend the technician reconstructs the diagram above from an existing diagram that was found It represents the new internetwork design It shows the planned routers hubs switches circuits and the servers workstations at each site The server at the Center site is a file server accessed only by workstations on this internetwork The ...

Страница 133: ...twork Use the network address assigned along with the subnetting requirements to subnet the network From the IP addressing scheme assign IP addresses to the appropriate interfaces on all routers and computers in the internetwork Use the diagram below as a guide Obtain approval of this phase of development from the team leader before proceeding to Phase 3 Instructor approval ___________________Date...

Страница 134: ...outer and workstations Use the diagram and planning sheets to create a basic configuration for the router The checklist below will help keep track of the configuration process Boaz Center Eva Hostname Console Password Secret Password VTY Password Serial 0 0 IP address Serial 0 1 IP address Serial 0 0 Clock Rate Serial 0 1 Clock Rate Fa 0 0 IP address Fa 0 1 IP address Enable the interfaces Add Rou...

Страница 135: ...udy Copyright 2004 Cisco Systems Inc Boaz Center Eva Host Table contains all routers and servers Message of the Day Serial 0 0 description Serial 0 1 description Fa 0 0 description Fa 0 1 description Instructor approval _____________________________ Date __________________ ...

Страница 136: ...et except to access File Server 1 Each router can telnet to the other routers and access any device on the network The team lead asks the technician to write down a short summary of the purpose of each ACL the interfaces upon which they will be applied and the direction of the traffic Then list the exact commands that will be used to create and apply the ACLs to the router interfaces Before the AC...

Страница 137: ...te documentation that is logically organized to make troubleshooting simpler Configuration management documentation Boaz Center Eva show cdp neighbors show ip route show ip protocol show ip interface brief show version show hosts show startup config Security management documentation Boaz Center Eva show ip interface show ip access lists Instructor approval _____________________________ Date ______...

Страница 138: ...w the security was tested A plan for monitoring the network should also be included Technical Documentation The technical documentation should include details of the network topology Use CND Visio or any paint program to draw the network Use the tables in the working copy of the case study as a reference and enter all table information into a spreadsheet program such as Microsoft Excel The spreads...

Страница 139: ...138 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Case Study Copyright 2004 Cisco Systems Inc show ip interface show version show hosts show startup config show ip access list ...

Страница 140: ...anges or a subnet of one Class Range A 10 0 0 0 10 255 255 255 B 172 16 0 0 172 31 255 255 C 192 168 0 0 192 168 255 255 The routing protocol should be IGRP The first part of Phase 1 should probably be completed as a class so that students understand the purpose of the case study Along with a discussion of Phase 1 the deliverable piece should also be covered The instructor should decide whether or...

Страница 141: ... should enter their configurations and test them on the routers Phase 4 Access Control Lists This Phase should be completed after Module 11 This is a most critical portion of the case study Students must develop an access control list on paper first then type the ACL into a word processing application The instructor should guide the students through the process of copying and pasting ACLs into the...

Страница 142: ...te Gateway of last resort is not set 172 16 0 0 16 is subnetted 4 subnets I 172 16 128 0 100 10476 via 172 16 64 1 00 00 20 Serial0 I 172 16 32 0 100 8576 via 172 16 64 1 00 00 20 Serial0 C 172 16 96 0 is directly connected Ethernet0 C 172 16 64 0 is directly connected Serial0 Boaz show ip protocols Routing Protocol is igrp 11 Sending updates every 90 seconds next due in 34 seconds Invalid after 2...

Страница 143: ...me is 5 hours 6 minutes System restarted by power on System image file is flash igs j l 111 5 booted via flash Cisco 2500 68030 processor revision N with 6144K 2048K bytes of memory Processor board ID 22650091 with hardware revision 00000000 Bridging software SuperLAT software copyright 1990 by Meridian Technology Corp X 25 software Version 2 0 NET2 BFE and GOSIP compliant TN3270 Emulation softwar...

Страница 144: ...dress 172 16 64 2 255 255 224 0 no fair queue interface Serial1 no ip address shutdown router igrp 11 network 172 16 0 0 ip host Centre 172 16 64 1 172 16 128 1 172 16 32 1 ip host Boaz 172 16 64 2 172 16 96 1 ip host Eva 172 16 128 2 172 16 160 1 no ip classless access list 101 permit ip 172 16 96 0 0 0 31 255 host 172 16 32 5 access list 101 permit ip 172 16 96 0 0 0 31 255 172 16 96 0 0 0 31 25...

Страница 145: ...y Discovery is disabled Policy routing is disabled Serial0 is up line protocol is up Internet address is 172 16 64 2 19 Broadcast address is 255 255 255 255 Address determined by setup command MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is enabled Outgoing access list is not set Inbound access list is not set Proxy ARP is enabled Security level is default Split horizo...

Страница 146: ...5 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Case Study Copyright 2004 Cisco Systems Inc deny tcp 172 16 96 0 0 0 31 255 any eq telnet deny icmp 172 16 96 0 0 0 31 255 any 8 matches Boaz ...

Страница 147: ...ctly connected Ethernet0 I 172 16 96 0 100 8576 via 172 16 64 2 00 00 57 Serial0 C 172 16 64 0 is directly connected Serial0 Centre show ip protocol Routing Protocol is igrp 11 Sending updates every 90 seconds next due in 50 seconds Invalid after 270 seconds hold down 280 flushed after 630 Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is n...

Страница 148: ...0000000 Bridging software SuperLAT software copyright 1990 by Meridian Technology Corp X 25 software Version 2 0 NET2 BFE and GOSIP compliant TN3270 Emulation software copyright 1994 by TGV Inc 2 Ethernet IEEE 802 3 interfaces 2 Serial network interfaces 32K bytes of non volatile configuration memory 8192K bytes of processor board System flash Read ONLY Configuration register is 0x2102 Centre show...

Страница 149: ...00 interface Serial1 description Centre WAN interface to Eva ip address 172 16 128 1 255 255 224 0 clockrate 56000 router igrp 11 network 172 16 0 0 ip host Centre 172 16 64 1 172 16 128 1 172 16 32 1 ip host Boaz 172 16 64 2 172 16 96 1 ip host Eva 172 16 128 2 172 16 160 1 no ip classless banner motd CThis is a SECURE SYSTEM UNAUTHORIZED USERS will be prosecuted C line con 0 password cisco login...

Страница 150: ...sabled Gateway Discovery is disabled Policy routing is disabled Ethernet1 is administratively down line protocol is down Internet protocol processing disabled Serial0 is up line protocol is up Internet address is 172 16 64 1 19 Broadcast address is 255 255 255 255 Address determined by setup command MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is enabled Outgoing acces...

Страница 151: ... ICMP redirects are always sent ICMP unreachables are always sent ICMP mask replies are never sent IP fast switching is enabled IP fast switching on the same interface is enabled IP multicast fast switching is enabled Router Discovery is disabled IP output packet accounting is disabled IP access violation accounting is disabled TCP IP header compression is disabled Probe proxy name replies are dis...

Страница 152: ...72 16 64 0 100 10476 via 172 16 128 1 00 01 18 Serial1 Eva show ip protocol Routing Protocol is igrp 11 Sending updates every 90 seconds next due in 24 seconds Invalid after 270 seconds hold down 280 flushed after 630 Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Default networks flagged in outgoing updates Default networks acce...

Страница 153: ...f memory Processor board ID 06147980 with hardware revision 00000000 Bridging software SuperLAT software copyright 1990 by Meridian Technology Corp X 25 software Version 2 0 NET2 BFE and GOSIP compliant TN3270 Emulation software copyright 1994 by TGV Inc 1 Ethernet IEEE 802 3 interface 2 Serial network interfaces 32K bytes of non volatile configuration memory 8192K bytes of processor board System ...

Страница 154: ...escription Eva WAN interface to Centre ip address 172 16 128 2 255 255 224 0 router igrp 11 network 172 16 0 0 ip host Boaz 172 16 64 2 172 16 96 1 ip host Centre 172 16 64 1 172 16 128 1 172 16 32 1 no ip classless ip http server access list 103 permit ip 172 16 160 0 0 0 31 255 host 172 16 32 5 access list 103 permit ip 172 16 160 0 0 0 31 255 172 16 160 0 0 0 31 255 access list 103 deny tcp 172...

Страница 155: ... name replies are disabled Gateway Discovery is disabled Policy routing is disabled Serial0 is administratively down line protocol is down Internet protocol processing disabled Serial1 is up line protocol is up Internet address is 172 16 128 2 19 Broadcast address is 255 255 255 255 Address determined by setup command MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is ena...

Страница 156: ...ics v3 1 Instructor Guide Case Study Copyright 2004 Cisco Systems Inc permit ip 172 16 160 0 0 0 31 255 172 16 160 0 0 0 31 255 225 matches deny tcp 172 16 160 0 0 0 31 255 any eq telnet deny icmp 172 16 160 0 0 0 31 255 any 20 matches Eva ...

Страница 157: ...156 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendices Copyright 2004 Cisco Systems Inc V Appendices A Cisco Online Tools and Utilities B Instructional Best Practices ...

Страница 158: ...ources can be found on the Cisco Technical Assistance Center TAC website at http www cisco com tac To learn more about the Cisco TAC website visit http www cisco com public news_training tac_overview html This document introduces ten valuable resources that are available to users at cisco com A cisco com user ID and password is required to access all of the tools on the Cisco TAC website A user ID...

Страница 159: ...e Output Interpreter uses a collection of show command output to perform the analysis Users paste the output of one or more supported commands into Output Interpreter to receive a report that includes errors warnings and relevant troubleshooting information The report also includes crash analysis and error message decodes which were previously supported by the Stack Decoder and the Error Message D...

Страница 160: ... 1 Instructor Guide Appendix A Copyright 2004 Cisco Systems Inc 2 Error Message Decoder Explanations for console error message strings are listed in the Cisco Software System Messages guide http www cisco com cgi bin Support Errordecoder home pl ...

Страница 161: ... Cisco Systems Inc 3 Software Bug Toolkit The Software Bug Toolkit is a Web based resource that is used to search for software bugs based on version and feature sets The toolkit can be used to determine why a feature does not work http www cisco com cgi bin Support Bugtool launch_bugtool pl ...

Страница 162: ... A Copyright 2004 Cisco Systems Inc 4 IP Subnet Calculator IP Subnet Calculator is a Web based resource that is used to calculate the subnet mask based on several variables This tool can be used to verify network settings http www cisco com cgi bin Support IpSubnet home pl ...

Страница 163: ...r Guide Appendix A Copyright 2004 Cisco Systems Inc 5 Password Recovery Procedures This Web page is the source for Cisco password recovery procedures The password recovery procedure for every Cisco device can be found here http www cisco com warp public 474 ...

Страница 164: ...ection is an evolution of the Troubleshooting Assistant tool It allows users to interactively identify and troubleshoot common problems that involve hardware configuration and performance issues These solutions which are provided directly by TAC engineers help resolve networking problems http www cisco com kobayashi support tac tsa launch_tsa html ...

Страница 165: ...Inc 7 Software Advisor The Software Advisor helps users choose the appropriate software for network devices Users can match software features to Cisco IOS and CatOS releases compare IOS releases or find out which software releases support their hardware http www cisco com cgi bin Support CompNav Index pl ...

Страница 166: ...re Navigator II Cisco Feature Navigator II is a Web based application that allows users to quickly find the right Cisco IOS Software release for the features they want to run on their networks Users can search by feature search by release or compare two different releases http tools cisco com ITDIT CFN jsp index jsp ...

Страница 167: ... be used to access the same resources used by TAC Users can search the entire TAC database for technical documents published by the Cisco TAC for TAC technical support tools for documents that are located on http www cisco com or for entries in the Networking Professionals Connection discussion forums http www cisco com kobayashi support tac s_tac shtml ...

Страница 168: ...o as best practices The Academy teaching community consists of over 20 000 instructors Each instructor brings unique experiences and talents to the program This section presents options that have been successful for certain audiences and certain topics This section does not imply that all of these techniques apply equally well to all students in all curricula These techniques or best practices for...

Страница 169: ...t prepares students teachers and administrators for a business world that demands proficiency in information technology The ISTE has written National Educational Technology Standards NETS for students teachers and administrators The NETS for Students NETS S are divided into six categories Basic operations and concepts Social ethical and human issues Technology productivity tools Technology communi...

Страница 170: ...uctivity and professional practice Support management and operations Assessment and evaluation Social legal and ethical issues Web Links ISTE website http www iste org B 1 3 Literacy math and science standards Since the late 1980s states and school districts across the United States have begun to raise standards in core subjects Academic standards are now used to clearly identify what students sho...

Страница 171: ... Teachers of English http www ncte org standards standards shtml Council for Teachers of Math http www nctm org National Science Teachers Association http www nsta org American Association for the Advancement of Science http www aaas org The National Academy of Science http www nas edu National Research Council NRC http www nrc cnrc gc ca ...

Страница 172: ...ves and give students more opportunities to use the knowledge in practical applications This study also finds dissimilarities in teaching styles In the United States problem solving usually occurs after the teacher has demonstrated the process to find the correct answer based upon mathematical principals Students will then apply this problem solving process to similar mathematical problems In coun...

Страница 173: ...ach Constructivist learning is derived from the Latin word constructus which means to build The Cisco Networking Academy allows students to develop knowledge that they can use in the real world Constructivist learning is also known as student centered learning This type of learning is recognized as an exemplary instructional model This method of teaching puts the students in control of their own l...

Страница 174: ...s students struggle with challenges teachers can introduce problem solving strategies and encourage students to work through what is perceived to be a difficult situation As students master the course content teachers can introduce the next level of challenge Web Links Pedagogical Application of Technology A Consortium for Change http courses temple edu ta contructivist htm B 1 6 Multiple intellig...

Страница 175: ...udent to process new information through thought and reflection Strong intrapersonal intelligence indicates a strong personal connection to feelings and emotions which can take a student to a higher level of consciousness in learning Interpersonal intelligence allows a student to accurately perceive the emotions feelings motivations and intentions of others Strong interpersonal intelligence indica...

Страница 176: ...ject What do learners Want to find out about the subject How are learners going to go about finding the answers What do learners anticipate Learning What have they learned Can learners Apply their learning to other subjects or projects What new Questions have surfaced throughout the time of inquiry Within any inquiry based learning activity or project the range of control must remain flexible Ther...

Страница 177: ...help if they need it Use contrasting light and dark colors to help students differentiate between cables and routers Use proper lighting in all areas of the lab to help students see more effectively Provide pocket or lighted magnifiers for reading to assist students with low vision Provide hats or visors to reduce the glare that is associated with many vision disorders Use bold lines and write in ...

Страница 178: ...aking distinctly and not too fast When there are physically impaired students in a classroom here are some general considerations to keep in mind Be prepared to give physically impaired students more time if necessary to complete hands on labs tasks and exams Consider giving these students shorter work assignments with rest periods built into the schedule Establish open communication with the stud...

Страница 179: ... learning disabilities will have a higher level of motivation to succeed in response to peer interactions than when working alone Teach students to write their own personal learning goals Instruct them to write short and long term goals and provide feedback on their progress Provide numerous models examples and representations of curriculum concepts Speak aloud in class to benefit students with le...

Страница 180: ...ties process information The hands on labs will greatly benefit these students Instruct students to talk about or write about what they have learned what they found interesting and what they still need to learn at the end of each topic Reflection moves new knowledge into long term memory Offer additional time for students with learning disabilities to formulate responses to questions This extra ti...

Страница 181: ...ble installation materials CCNA 1 students acquire lab skills that enable them to perform the following tasks Configure networking properties on workstations Make and test patch cables Install and test cable runs jacks and patch panels The required lab equipment for CCNA 2 includes workstations hubs switches and routers CCNA 2 students acquire lab skills that enable them to perform the following t...

Страница 182: ... equipment is also recommended Students acquire lab skills in the following WAN technology areas PPP ISDN Frame Relay Students also must pass a comprehensive lab skills exam as part of this course Standard and premium lab bundles are available A variety of optional bundles are also available The student to equipment ratio should be as low as possible Web Links Cisco Networking Academy Program http...

Страница 183: ...routed and switched networks with substantial remote access The CCNP curriculum consists of four courses Advanced Routing Remote Access Multilayer Switching Network Troubleshooting The curriculum is lab intensive Approximately 50 percent of all class time spent on lab exercises The required lab equipment for CCNP 1 includes workstations routers and switches CCNP 1 students acquire lab skills that ...

Страница 184: ...ting Basic network security The required lab equipment in CCNP 3 includes workstations hubs switches and routers CCNP 3 students acquire lab skills such as the following Switch and VLAN configuration Multilayer switching and redundancy technology implementation Campus LAN design Required lab equipment for CCNP 4 includes workstations routers switches and a WAN simulator CCNP 4 students acquire lab...

Страница 185: ...he NETLAB automation and sharing capabilities allow Cisco Networking Academies to maximize the use of their equipment and save money in the process The networking hardware is identical to the lab bundle used in Cisco Networking Academies worldwide This will allow students to maintain a consistent topology to practice the configuration commands covered in the Academy curriculum and labs The use of ...

Страница 186: ...nt the concepts learned in the classroom Instructors can also identify and correct common mistakes that are made by students during lab exercises NETLAB is currently deployed as a pilot program at selected Cisco Networking Academies Upon the successful completion of this pilot program Cisco will offer NETLAB to all Cisco Networking Academies For information on how to become one of the Academies th...

Страница 187: ...urriculum The Help feature in the simulation can be used to obtain the necessary information to complete the required task There are generally three levels of Academy simulations Syntax drill The simplest and most scripted activity can be thought of as a syntax drill This exercise gives students immediate practice when a new command or procedure is introduced These simulations help move online cur...

Страница 188: ...ailable and free to all CCNA and CCNP students Flash simulations are meant to complement hands on experience with lab equipment and actual programming These simulations have many cognitive benefits For example simulations allow students to perform a simulative lab activity prior to an actual lab activity This helps students increase their level of comprehension in a simulated environment before th...

Страница 189: ...188 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc Figure 2 Sponsored Curriculum Labs Figure 3 Sponsored Curriculum Labs ...

Страница 190: ...ting Systems which is sponsored by Hewlett Packard Company is an extensive introduction to multiuser multitasking network operating systems NOSs This course will discuss the characteristics of the Linux Windows 2000 NT and XP NOSs Hands on labs will utilize the Windows 2000 and Linux NOSs Students will explore a variety of topics such as installation procedures security issues back up procedures a...

Страница 191: ...s provides a conceptual comprehension of Object Oriented programming The course also teaches students how to use the JAVA language object oriented technologies to solve business problems Topics include the language fundamentals and the Java language application programming interface API Students will learn how to use this language to create classes objects and applications This course also address...

Страница 192: ...Inc longer delivery model or some pre selection and screening of students About half of the course time is spent on the instructor facilitated online multimedia material and the rest is spent on lab exercises Web Links Instructor Community New Courses http cisco netacad net cnacs prot doc new_courses html ...

Страница 193: ...192 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc B 2 6 Emerging technologies Figure 1 PIX Firewall PhotoZoom Figure 2 IP Phone ...

Страница 194: ...lab bundle which will allow for the successful implementation of the labs The goal of these course will be to train professionals who can implement network security IP telephony wireless LANs and other networking technologies Web Links Network security issues http cisco com warp public 779 largeent issues security IP Telephony http www cisco com warp public 779 largeent learn technologies IPteleph...

Страница 195: ...he IT industry Instructors will typically need to spend more time on lab preparation to teach students about troubleshooting However the overall benefit to the student is worth this investment Troubleshooting is used to identify and correct hardware software and programming problems One instructional troubleshooting method involves deliberately introducing a finite number of problems in a structur...

Страница 196: ...ities for students to practice diagnosis and repair Web Links Teaching Methods Web Resources http www mhhe com socscience education methods resources html The Universal Troubleshooting Process UTP http www troubleshooters com tuni htm Journal of Technology Education http scholar lib vt edu ejournals JTE v2n2 html deluca html ...

Страница 197: ...e week challenge that teaches more complex tasks might be called Wire the School Computer Lab NetDay is a great example of challenge based learning and Cisco encourages instructors to incorporate it into their classes Teaching and learning environments extend beyond the lab setting Opportunities for real world applications emerge when students can use their networking skills in projects that contr...

Страница 198: ...ience This really helped me see the big picture of how everything works together and what tech support is like Another example of community outreach takes place in Washington D C where Cisco Systems partners with Mary s Center for Maternal and Child Care With help from a volunteer system engineer and three students from the Cisco Networking Academy Program at Bell Multicultural High School Mary s ...

Страница 199: ...ve problem solving procedure For Internet problems and issues related to general engineering problem solving matrices are useful when there many alternatives for a given number of constraints Chapter 1 The Engineering Problem Solving Cycle of the Engineering Problem Solving for Mathematics Science and Technology Education uses the problem solving matrix to introduce the problem solving cycle and i...

Страница 200: ...rom failed problem solving attempts to save time when they try to solve new problems Chapter 5 Research Documentation and Testing is a good resource for students to learn how to conduct site surveys keep work logs produce engineering reports and create portfolios Web Links Dartmouth Problem Solving and Design Method http thayer dartmouth edu teps index html ...

Страница 201: ...d carousel brainstorming This is a strategy used for creative thinking when multiple solutions are possible to solve an issue or problem During a carousel session problems are documented on large sheets of chart paper around a room Students in small cooperative groups are given different colored pens and asked to go around the room and brainstorm solutions to the problems listed on the different c...

Страница 202: ...ssue or problem Adapt Can the materials methods processes or situations be used in another way to find a solution Modify Can this be made bigger stronger and more frequent Can it be made smaller and more compact Put to other uses Can this be used instead of other materials methods processes or situations Eliminate Can parts of this be eliminated Reverse Can the work be done backwards Can this proc...

Страница 203: ...important in many professions such as law medicine and business Case studies that are specified in the course or instructor developed can be used to integrate many concepts throughout the Academy curricula Figure 1 shows a case study from the CCNP curriculum The International Travel Agency is a fictitious business for which a CCNP certified individual might be asked to provide network services ...

Страница 204: ...Copyright 2004 Cisco Systems Inc Web Links Use of Master Classroom Technology to Implement a Case Study Approach to Learning http www mtsu edu itconf papers96 MASTER HTM Case Study Teaching in Science A Bibliography http ublib buffalo edu libraries projects cases article2 htm ...

Страница 205: ...or their favorite websites The online documentation for Cisco Systems Sun Microsystems HP Panduit and other sponsors is particularly important In terms of bandwidth capabilities the Web resources related to networking far exceed any textbook or online curriculum Students must find the resources and be cautious consumers The ability to use the Internet as a resource is a very useful skill for stude...

Страница 206: ...rter time frame as a mini lecture Mini lectures focus on smaller chunks of content that students may need to hear at some point in the learning process An effective classroom strategy for this style of instruction is to present all lectures at a predetermined class time and as a precursor to individual and group work The current focus on the cooperative dynamics of learning has taken attention awa...

Страница 207: ...ting Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc Studies have found that relatively short engaging lectures that include demonstrations are excellent adjuncts to the online curriculum and lab activities ...

Страница 208: ...nline or self paced program there is a strong need for a course facilitator This person helps get students excited and keeps them excited about what they are learning This person also monitors student progress The online lessons are an important part of Academy instruction However they should not be overly used Remember that a primary goal of the Cisco Networking Academy Program is to train studen...

Страница 209: ...culum Groups of three students to complete cabling lab and programming activities Groups of five students to take oral exams and work as network or programming teams There are a variety of ways to engage students through cooperative learning Instructors can divide the class into student groups to conduct reviews ask questions learn content and work on performance labs or other activities It is imp...

Страница 210: ...lt of the team effort may contribute to the grades of all or individual team members Competitive teams The selection of team members for competitive team activities is similar to the previous description Each competitive team has a specific purpose They compete with other teams to determine which team can accomplish the criteria and objectives of a performance task with the most speed and accuracy...

Страница 211: ...ystems Inc Student led discussions Demonstrations Presentations Web Links Teaching Strategies Group Work and Cooperative Learning http www crlt umich edu tstrategies tsgwcl html Enhancing Student Thinking through Collaborative Learning ERIC Digest http www ericfacility net ericdigests ed422586 html ...

Страница 212: ...is distributed so each home group receives one of the three sections of content The use of color codes is a useful technique to implement within this activity Three different colors are used to distinguish between the three content sections to be learned Members from each group move to an expert group where the main points of the content are discussed Members of the expert group process this new i...

Страница 213: ...sroom is approximately 1 5 seconds Research indicates that with just a 3 second waiting period student answers are more accurate and organized Instructors should ask students questions about the concepts that they will continue to understand long after the little details fade away from their short term memories These concepts will require teachers and students to reflect on the intrinsic value of ...

Страница 214: ...ovements on complex assessments Better classroom management Instructors who use question and answer techniques to teach networking should increase the wait time to see if student learning improves Instructors can read an article written by Dr Rowe to learn more about this concept Rowe M 1974 Relation of wait time and rewards to the development language logic and fate control a part one wait time J...

Страница 215: ... T chart The left side of the chart includes an area for items that might qualify as plus minus or interesting Students respond to the following questions in relation to specific content What do they consider to be a Plus What do they consider to be a Minus What do they consider to be an interesting process comment or question Students record their thoughts on the right side of the chart as they a...

Страница 216: ...215 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc B 4 7 Graphic organizers Figure 1 Cluster Diagram Figure 2 Problem Solving Matrix ...

Страница 217: ...216 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc Figure 3 Flowchart Figure 4 Block Diagrams ...

Страница 218: ...217 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc Figure 5 Extended Star Topology in a Multi Building Campus Figure 6 Main Building First Floor ...

Страница 219: ...218 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc Figure 7 Digital Signal Figure 8 Spectrum Diagram of a Voltage versus Frequency Graph ...

Страница 220: ...219 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc Figure 9 Data Encapsulation Figure 10 Ethernet and IEEE 802 3 Frame Format ...

Страница 221: ...ers such as exposition narratives and graphics Graphic organizers are shown in Figures through These methods were publicized by a psychologist named David Ausubel in the late 1960s These techniques help students make connections between their current knowledge and the information needed to reach a more complete comprehension of a learning objective Graphic organizers also enable students to arrang...

Страница 222: ...anches of a process Flowcharts are used throughout the curriculum to describe configuration troubleshooting and communications processes Block diagrams are standard in the electronics industry A few simple symbols or pictorials and arrows are used to indicate the flow of information Block diagrams include simple descriptions of the functions of the various blocks Block diagrams represent an interm...

Страница 223: ... Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc Collision AC DC RFI EMI Encoding Transmission errors Web Links David Ausubel Advance Organizers http chd gse gmu edu immersion knowledgebase strategies cognitivism AdvancedOrganizers htm ...

Страница 224: ...gths and resources to the goal in spite of any diversions disappointments or difficulties they encounter To successfully reach their goals students need to make connections with other people They should seek out people with the knowledge to advance their comprehension and the passion to keep them motivated and encouraged It is a fundamental psychological principal that learning requires the assimi...

Страница 225: ...224 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc B 4 9 Kinesthetic activities Figure 1 Kinesthetic Activities Figure 2 Kinesthetic Activities ...

Страница 226: ...d show an activity that can be done with eight students Each student represents a specific place value of 128 64 32 16 8 4 2 or 1 for 8 bit binary numbers The instructor picks a number between decimal 0 and 255 and each student must decide if they should sit to represent binary 0 or stand to represent binary 1 Many IT processes and algorithms can be expressed through kinesthetic activities Role pl...

Страница 227: ...ir levels of comprehension through the discussion Small groups each discuss a portion of the questions and explain their findings to other groups to demonstrate their knowledge This is an example of the jigsaw technique The entire class plays a game in which one person states a fact which represents the correct answer to a question and leaves out an important piece of information The rest of the c...

Страница 228: ...side a period of time for this process The teacher and students can use this time to reflect on completed tasks or make predictions about future experiences Thoughts and ideas can be written down in a dedicated personal paper space or in a word processor file These thoughts can take many forms such as words sentences illustrations maps charts magazine pictures and newspapers Journal entries can ta...

Страница 229: ...Discussions Activities related to lesson content Personal analysis that shows a connection with the content purpose Questions or statements that indicate a need for further clarification or inquiry Attention to the process required to accomplish an important task Application of learned material to other content or subjects A demonstration of the connection between concept or content Thoughtfulness...

Страница 230: ...8 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc Web Links Student Reflection Questions http pblmm k12 ca us PBLGuide PlanAssess StReflectionQuestions html ...

Страница 231: ...ic assessment is the control it gives to students Students can create their own rubrics based on established standards and performance objectives Assessment occurs continuously through self monitoring and self evaluation Students who are given direction and the freedom to choose their path of learning are empowered to accomplish high levels of achievement For Academy courses rubrics create specifi...

Страница 232: ...nd teachers can help students organize and prepare for learning through advance knowledge of their assessment expectations It also allows students to contribute to the development of the grading scale for their performance labs or activities Web Links RUBISTAR http rubistar 4teachers org Rubrics and Assessments http home socal rr com exworthy rubric htm ...

Страница 233: ...s they created for different scenarios Community projects are also good examples of accomplishments A portfolio is a paper electronic or online collection that shows the best work of a student As with any educational initiative portfolios are continually revised and improved Many secondary school districts encourage portfolio based assessments The Cisco Networking Academy Program is well suited fo...

Страница 234: ...233 238 CCNA 2 Routers and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc B 5 5 Oral exams Figure 1 Oral Exams Figure 2 Oral Exams ...

Страница 235: ...exam questions answers and rubrics prior to the exam session Establish scheduled exam times which can be after school if necessary Students study and complete assessment activities in groups Then each individual member of a team enters the room alone and is asked one of the questions by the board The students do not know which question they will be asked in advance This method of oral testing usua...

Страница 236: ... The number of routers to connect will vary based on equipment access This process is one that distinguishes the Cisco Networking Academy Program from all other programs When students graduate from the Academy they have been tested on their hands on expertise with equipment This practice supports authentic assessment and gives students higher credibility in the job market Lab exams include all of ...

Страница 237: ...uters and Routing Basics v3 1 Instructor Guide Appendix B Copyright 2004 Cisco Systems Inc Web Links Certification Magazine http www certmag com issues aug01 feature_long cfm CCIE http www cisco com warp public 625 ccie ...

Страница 238: ...ors in all Academy curriculums The following example uses UNIX Equity Do all Academy students have adequate access to information about UNIX Curriculum Do the online curriculum and skills based labs provide ample opportunities for students to learn about UNIX Teaching Do all Academy students have access to instructors who use instructional best practices to teach UNIX Learning Do students have ade...

Страница 239: ...2004 Cisco Systems Inc As instructors work through this orientation they are encouraged to revisit these essential questions In this section Cisco presented some useful content tools and perspectives Ultimately instructors should decide what teaching methods are best for their students ...

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