CCNA Study Notes1(3)
添加时间: 2007-9-8 2:50:42 作者: Cisco认证考试 阅读次数:109 来源: http://www.d9soft.com
Following is a partial example of the setup routine:
Router# setup
--- System Configuration Dialog ---
At any point you may enter a question mark '?' for help.
Use ctrl-c to abort configuration dialog at any prompt.
Default settings are in square brackets '[]'.
Continue with configuration dialog? [yes]:
First, would you like to see the current interface summary? [yes]:
Interface IP-Address OK? Method Status Protocol
Ethernet0 172.16.72.2 YES manual up up
Serial0 unassigned YES not set administratively down down
Serial1 172.16.72.2 YES not set up up
Configuring global parameters:
Enter host name [Router]:
The enable secret is a one-way cryptographic secret used
instead of the enable password when it exists.
Enter enable secret []:
The enable password is used when there is no enable secret
and when using older software and some boot images.
Enter enable password [ww]:
Enter virtual terminal password [ww]:
Configure SNMP Network Management? [yes]:
Community string [public]:
Configure IP? [yes]:
Configure IGRP routing? [yes]:
Your IGRP autonomous system number [15]:
Configuring interface Ethernet0:
Is this interface in use? [yes]:
Configure IP on this interface? [yes]:
IP address for this interface [172.16.72.2]:
Number of bits in subnet field [8]:
Class B network is 172.16.0.0, 8 subnet bits; mask is /24
.
.
.
15. Copy and manipulate configuration files
You can copy a configuration file from a TFTP server to the running configuration or to the startup configuration. When you copy a configuration file to the running configuration, you copy to and run the file from RAM. When you copy a configuration file to the startup configuration, you copy it to the nonvolatile random-access memory (NVRAM).
Step 1 Copy a file from a TFTP server to the router copy tftp running-config
or
Copy tftp startup-config
Step 2 When prompted enter the IP address or domain ip-address or name
name of the server
Step 3 If prompted, enter the filename of the configuration filename
file
Configuration files can also be copied from an rcp server to the local router as well. You must first specify the remote username:
ip rcmd remote-username username
Use steps as above except replace tftp with rcp
to view the configuration in NVRRAM show startup-config
to view the current running configuration show running-config
to re-execute the configuration commands located in NVRAM configure memory
to erase the contents of NVRAM erase startup-config
16. List the commands to load Cisco IOS from: flash memory, a tftp server or ROM.
To configure a router to automatically boot an image in Flash memory, perform the following tasks:
Task Command
Step 1 Enter configuration mode form the terminal configure terminal
Step 2 Enter the filename of an image stored in Flash memory boot system flash [filename]
boot system flash slot0:[filename]
boot system flash slot1:[filename]
boot system flash bootflash:[filename]
Step 3 Set the configuration register to enable loading image config-register value
from Flash memory (generally 0x2102)
Step 4 Save configuration file copy running-config startup-config
To configure a route to load a system image from a network server using TFTP, rcp or MOP, use the following commands:
Task Command
Step 1 Enter configuration mode form the terminal configure terminal
Step 2 Specify the system image to be booted boot system [rcp tftp] filename [ip address]
from a network server using rcp, TFTP or
or MOP. boot system mop filename [mac-address] [int]
Step 3 Set the configuration register to enable loading config-register value
image from a network server (generally 0x010F)
Step 4 Save configuration file copy running-config startup-config
To specify the use of the ROM system image as a backup to other boot instructions in the configuration file, complete the following:
Task Command
Step 1 Enter configuration mode form the terminal configure terminal
Step 2 Enter the filename of an image stored in Flash memory boot system rom
Step 3 Set the configuration register to enable loading image config-register value
from ROM (generally 0x0101)
Step 4 Save configuration file copy running-config startup-config
17. Prepare to backup, upgrade and load a backup Cisco IOS software image.
18. List the key internetworking functions of the OSI Network layer and how they are performed in a router.
19. Describe the two parts of network addressing, then identify the parts in specific protocol address examples.
A network layer address identifies an entity at the network layer of the OSI reference model. Network addresses usually exist within a hierarchical address space. They are sometimes called virtual or logical addresses. The relationship of a network address with a device is logical and unfixed. It is typically based either on physical network characteristics (the device is on a particular network segment) or on groupings that have no physical basis (the device is part of an AppleTalk zone). End systems require one network layer address for each network layer protocol they support. (This assumes that the device has only one physical network connection.) Routers and other internetworking devices require one network layer address per physical network connection for each network layer protocol supported. For example, a router with three interfaces, each running AppleTalk, TCP/IP, and OSI, must have three network layer addresses for each interface. The router therefore has nine network layer addresses.
20. List problems that each routing type encounters when dealing with topology changes and describe techniques to reduce these problems.
Distance Vector protocols, like RIP, specify a number of features designed to make their operation more stable in the face of rapid network topology changes. These include a hop-count limit, hold-downs, split horizons, and poison reverse updates.
Hop-Count Limit - RIP permits a maximum hop count of 15. Any destination greater than 15 hops away is tagged as unreachable. RIP's maximum hop count greatly restricts its use in large internetworks, but prevents a problem called count to infinity from causing endless network routing loops.
Hold-Downs - Hold-downs are used to prevent regular update messages from inappropriately reinstating a route that has gone bad. When a route goes down, neighboring routers will detect this. These routers then calculate new routes and send out routing update messages to inform their neighbors of the route change. This activity begins a wave of routing updates that filter through the network.
Triggered updates do not instantly arrive at every network device. It is therefore possible that a device that has yet to be informed of a network failure may send a regular update message (indicating that a route that has just gone down is still good) to a device that has just been notified of the network failure. In this case, the latter device now contains (and potentially advertises) incorrect routing information.
Hold-downs tell routers to hold down any changes that might affect recently removed routes for some period of time. The hold-down period is usually calculated to be just greater than the period of time necessary to update the entire network with a routing change. Hold-down prevents the count-to-infinity problem.
Forwarding State - A port in the forwarding state forwards frames, as shown in Figure C-5. The port enters the forwarding state from the learning state through the operation of Spanning-Tree Protocol.
Disabled State - A port in the disabled state does not participate in frame forwarding or the operation of Spanning-Tree Protocol. A port in the disabled state is virtually nonoperational.
63. Describe the benefits of Virtual LANs.
VLANs provide the following benefits:
Reduced Administration Costs - Moves, adds, and changes are one of the greatest expenses in managing a network. VLANs provide an effective mechanism to control these changes and reduce much of the cost of hub and router reconfiguration.
Controlling Broadcast Activity - Similar to routers, VLANs offer an effective mechanism for setting up firewalls in a switch fabric, protecting the network against broadcast problems that are potentially dangerous, and maintaining all the performance benefits of switching.
Better Network Security - You can increase security easily and inexpensively by segmenting the network into distinct broadcast groups. VLANs therefore can be used to provide security firewalls, restrict individual user access, flag any unwanted intrusion to the network, and control the size and composition of the broadcast domain.
Leveraging Existing LAN Hub Investments - Organizations have installed many shared hub chassis, modules, and stackable devices in the past three to five years. You can leverage this investment by using backplane hub connections. It is the connections between shared hubs and switches that provide opportunities for VLAN segmentation.
上一篇文章: CCNA Study Notes1(2) 下一篇文章: CiscoCCNP-BCRAN(1)
相关文章: