Có 80+ tài liệu thuộc chủ đề "luyện thi CCNA"
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Depending on the Cisco router model, the LED indicators vary.. The upper LED on the daughter card indicates the activity on serial 1 port on the daughter card. The lower LED on the daughter card indicates the activity of the WAN, or BRI port. Figures 11-2 and 11-3 illustrate the router LED indicators.. In this lab, you use the System...
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Screen output varies, depending on Cisco IOS Software level and router configuration.. Suppose that a user wants to set the router clock. The following exercise illustrates one of the many uses of the help function. The task is to set the router clock. Assuming that the command is not known, proceed using the following steps:. Step 1 Use ? to...
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Troubleshooting Cisco IOS Software. Several things could prevent the router from booting properly:. Incorrect configuration register value. When the router boots, it looks in the configuration file for a boot system statement.. This statement can force the router to boot from another image instead of the Cisco IOS Software image in Flash. An incorrect configuration register setting prevents the Cisco...
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Privileged Mode Command List. Privileged EXEC mode provides a detailed examination of the router and allows con- figuration changes to be made to the router. From privileged EXEC mode, other modes can be entered. privileged EXEC mode must be entered before entering these other modes (see the next section, “Router Configuration Modes”).. To access privileged mode from user EXEC mode,...
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Example 12-5 show version Command Output. ROM: 4500-XBOOT Bootstrap Software, Version 10.1(1) RELEASE SOFTWARE (fc1) router uptime is 1 week, 3 days, 32 minutes. Example 12-6 show interfaces Command Output. continues Example 12-4 show protocols Command Output (Continued). A serial interface can be configured from the console or through a virtual terminal line.. Serial interfaces require a clock signal to...
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Password Recovery. This section explains several password-recovery techniques for Cisco routers and Catalyst switches. You can perform password recovery on most of the platforms without changing hardware jumpers, but all platforms require that the router be rebooted. Password recovery can be done only from the console port (physically attached to the router).. Overview of Password Recovery. Three ways exist for...
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Understand how to create a network map of the environment. Learning About Neighboring and Remote Devices. CDP is used to obtain infor- mation about neighboring devices. This information shows the types of devices connected, the router interfaces they are connected to, the interfaces used to make the connections, and the model numbers of the devices. CDP is media and protocol...
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This section describes Telnet, ping, and traceroute, which can be used to obtain infor- mation about remote devices, as shown in Figure 13-3.. Figure 13-3 Testing Process Overview. Telnet is a virtual terminal protocol that is part of the TCP/IP protocol suite. Telnet performs at the application layer of the OSI model, and it depends on TCP to guarantee the...
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By starting from 0, you get a better picture of the current status of the network. The router includes hardware and software to aid it in tracking down problems on it or on other hosts in the network. The debug privileged EXEC command starts the con- sole display of the network events specified in the command parameter. Figure 13-10 displays...
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Locating and Loading Cisco IOS Software 649. The order in which the router looks for Cisco IOS Software images to load depends on the boot field setting in the configuration register. The configuration register is set so that the router examines the startup file in NVRAM for boot system options. The configuration register is a 16-bit register in NVRAM. The...
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After the capture is complete, you need to edit the configuration file to remove extra text. To create this file in a form to be copied and pasted back into the router, remove any unnecessary information from the captured configuration. You can add comments to the text to explain the various parts of the configuration. You can edit the configuration...
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In this chapter, you learned the following key points:. The default source for Cisco IOS Software depends on the hardware platform, but, most commonly, the router looks to the configuration commands saved in NVRAM.. You can use the show version command to display information about the Cisco IOS Software version that is currently running on the router.. You can enter...
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Routing protocol messages move between the routers. Interior Gateway Routing Protocol (IGRP). Enhanced Interior Gateway Routing Protocol (EIGRP). Figure 15-4 Router and Routing Protocols. The host addresses the data link frame to the router, using the address of one of the router’s interfaces. The router’s network layer process examines the incoming packet’s Layer 3 header to determine the destination network...
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Verifying Static Route Configuration. It is important to verify that the static routes are present in the routing table and that routing is working as expected after the static routes are configured. The show ip route command is used to make sure that the static route is present in the routing table.. Step 4 Verify that the route that was...
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Z) are connected by three link-state routers. Network discovery for link-state routing uses the following processes:. The router constructs this logical topology as a tree, with itself as root, consisting of all possible paths to each network in the link-state protocol internetwork. The router lists its best paths and the ports to these destination networks in the routing table. Figure...
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1102.book Page 709 Tuesday, May PM. Describe and test load balancing over multiple paths. 1102.book Page 710 Tuesday, May PM. Distance Vector Routing Protocols. Now that you have learned about routing protocols, you are ready to configure IP routing protocols. As you know, routers can be configured to use one or more IP routing protocols.. In this chapter, you learn...
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The router immediately sends another routing update on its other interfaces, rather than waiting for the routing update timer to expire. This wave of updates is transmitted throughout the network. Preventing Routing Loops with Hold-Down Timers. When a router receives an update from a neighbor indicating that a previously accessible network is now inaccessible, the router marks the route as...
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Its key characteristics include the following:. Note in Figure 16-11 that the 19.2-kbps path between the two hosts using the top routers is 2 hops. Because RIP path selection is based solely on the number of hops, in this case, RIP path selection chooses the 19.2-kbps link instead of the much faster T1 links.. Figure 16-11 RIP Uses Hop Count...
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The router sends update information out the two RIP interfaces. The output shows the router is using RIP-1 and broadcasts the update (address . The num- ber in parentheses represents the source address encapsulated into the IP header of the RIP update.. You can look for several problems in the debug ip rip output. A couple of the problems that...
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RouterA(config)# router igrp 101. Example 16-13 demonstrates how to configure IGRP using AS 101 on RouterA and RouterB.. To verify that IGRP has been configured properly, enter the show ip route command and look for IGRP routes signified by an I.. show running-config—Verifies that IGRP is enabled on the router.. show running-config interface interface—Verifies that the proper IP address has...