Cisco Chapter 2 Flashcards
Network Operating System
Operating systems for routers
Enables device hardware to function
Provides an interface for users to interact
IOS
(Cisco) Internetwork Operating System
Operating Systems
Like Windows an OS
Shell
The user interface that allows users to request specific tasks from the computer. These requests can be made either through the CLI or GUI interfaces
Kernel
Communicating between Computer Hardware and Software
Home routers
OS = firmware
Shell
A command-line interface (CLI)
A CLI-based network operating system also used on Intermediary Network Devices
A graphical user interface (GUI)
mostly used for computers
primarily focus
you will focus primarily on Cisco IOS Release 15.x. The figure displays a list of IOS software releases for a Cisco Catalyst 2960 Switch.
Console
This is a physical management port that provides out-of-band access to a Cisco device. Out-of-band access refers to access via a dedicated management channel that is used for device maintenance purposes only. No configuration neccearly
SSH 22
SSH is a method for remotely establishing a secure CLI connection through a virtual
interface, over a network. Unlike a console connection, SSH connections require active networking services on the device including an active interface configured with an address.
Encrypted passwords by id
Telnet 23
SSH is a method for remotely establishing a secure CLI connection through a virtual interface, over a network. Unlike a console connection, SSH connections require active networking services on the device including an active interface configured with an address.
Telnet server
Telnet client
AUX port
Legacy auxiliary port is out-of-band and does not require networking services to be configured or available.
Terminal Emulation Programs
An excellent terminal emulation programs available for connecting to a networking device either by a serial connection over a console port or by a SSH/Telnet connection.
EXEC
User EXEC Mode - This mode has limited capabilities but is useful for basic operations. It allows only a limited number of basic monitoring commands but does not allow the execution of any commands that might change the configuration of the device. The user EXEC mode is identified by the CLI prompt that ends with the > symbol.
Priveleged EXEC
Privileged EXEC Mode - To execute configuration commands, a network administrator must access privileged EXEC mode. Higher configuration modes, like global configuration mode, can only be reached from privileged EXEC mode. The privileged EXEC mode can be identified by the prompt ending with the # symbol.
<li>Mode allows access to only a limited number of basic monitoring commands.</li>
<li>It is often referred to as “view-only” mode.</li>
<li>Mode allows access to only a limited number of basic monitoring commands.</li>
switch>
router>
It is often referred to as “view-only” mode.
Prive: The user can use any monitoring commands and execute configuration and management commands.
switch#
router#
Mode allows access to all commands and features.
Line Configuration Mode - Used to configure console, SSH, Telnet, or AUX access.
Interface Configuration Mode - Used to configure a switch port or router network interface.
ctrl+ shift+ 6
will cut off the current command
configure terminal
hostname
no hostname
?
config
name of the computer
turn hostname off
help
Priviliged EXEC password
enable secret
line console 0
password
login
Virtual terminal
(VTY) lines enable remote access to the device. To secure VTY lines used for SSH and Telnet,
Use line vty 0 15 global config command To enter it
specify the VTY password
password password command.
enable VTY access using the login command
Many Cisco switches support up to 16 VTY lines that are numbered 0 to 15
Encrypt Passwords in configuration file
service password-encryption to make them:
Switch(config)# service password-encryption
show running-config to check
Banner Messages
config terminal enable secret (password) ctrl+ c to get priv exect mode enable (password) showrunning-config spacebar see more line console 0 service-password-encryption banner motd
banner motd #
startup-config
The file stored in Non-volatile Random Access Memory (NVRAM) that contains all of the commands that will be used by the device upon startup or reboot. NVRAM does not lose its contents when the device is powered off.
running-config
The file stored in Random Access Memory (RAM) that reflects the current configuration. Modifying a running configuration affects the operation of a Cisco device immediately. RAM is volatile memory. It loses all of its content when the device is powered off or restarted.
.
As shown in the figure, use the show running-config privileged EXEC mode command to view the running configuration file. To view the startup configuration file, use the show startup-config privileged EXEC command.
If power to the device is lost or if the device is restarted, all configuration changes will be lost unless they have been saved. To save changes made to the running configuration to the startup configuration file use the copy running-config startup-config privileged EXEC mode command.
SVIs
switch virtual interfaces. These ports do not support Layer 3 IP addresses. Therefore, switches have one or more switch virtual interfaces
A Layer 2 switch does not need an IP address. The IP address assigned to the SVI is used to remotely access the switch. An IP address is not necessary for the switch to perform its operations.
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In order for an end device to communicate over the network, it must be configured with a unique IPv4 address and subnet mask. IP address information can be entered into end devices manually, or automatically using Dynamic Host Configuration Protocol (DHCP).
To manually configure an IPv4 address on a Windows host, open the Control Panel > Network Sharing Center > Change adapter settings and choose the adapter. Next right-click and select Properties to display the Local Area Connection Properties shown in Figure 1.
Highlight Internet Protocol Version 4 (TCP/IPv4) and click Properties to open the Internet Protocol Version 4 (TCP/IPv4) Properties window shown in Figure 2. Configure the IPv4 address and subnet mask information, and default gateway.
Manual IP Address Configuration for End Devices
Automatic IP Address Configuration for End Devices
In a network, DHCP enables automatic IPv4 address configuration for every end device that has DHCP enabled. Imagine the amount of time it would consume if every time you connected to the network, you had to manually enter the IPv4 address, the subnet mask, the default gateway, and the DNS server. Multiply that by every user and every device in an organization and you see the problem. Manual configuration also increases the chance of misconfiguration by duplicating another device’s IPv4 address.
As shown in Figure 1, to configure DHCP on a Windows PC, you only need to select “Obtain an IP address automatically” and “Obtain DNS server address automatically”. Your PC will search out a DHCP server and be assigned the address settings necessary to communicate on the network.
It is possible to display the IP configuration settings on a Windows PC by using the ipconfig command at the command prompt. The output will show the IPv4 address, subnet mask, and gateway information received from the DHCP server.
Use the Syntax Checker in Figure 2 to practice displaying the IPv4 address on a Windows PC.
Manual IP Address Configuration for End Devices
In order for an end device to communicate over the network, it must be configured with a unique IPv4 address and subnet mask. IP address information can be entered into end devices manually, or automatically using Dynamic Host Configuration Protocol (DHCP).
To manually configure an IPv4 address on a Windows host, open the Control Panel > Network Sharing Center > Change adapter settings and choose the adapter. Next right-click and select Properties to display the Local Area Connection Properties shown in Figure 1.
Highlight Internet Protocol Version 4 (TCP/IPv4) and click Properties to open the Internet Protocol Version 4 (TCP/IPv4) Properties window shown in Figure 2. Configure the IPv4 address and subnet mask information, and default gateway.
Note: The DNS server addresses are the IPv4 addresses of the Domain Name System (DNS) servers, which are used to translate IP addresses to domain names, such as www.cisco.com.
Automatic IP Address Configuration for End Devices
PCs typically default to using DHCP for automatic IPv4 address configuration. DHCP is a technology that is used in almost every network. The best way to understand why DHCP is so popular is by considering all the extra work that would have to take place without it.
In a network, DHCP enables automatic IPv4 address configuration for every end device that has DHCP enabled. Imagine the amount of time it would consume if every time you connected to the network, you had to manually enter the IPv4 address, the subnet mask, the default gateway, and the DNS server. Multiply that by every user and every device in an organization and you see the problem. Manual configuration also increases the chance of misconfiguration by duplicating another device’s IPv4 address.
As shown in Figure 1, to configure DHCP on a Windows PC, you only need to select “Obtain an IP address automatically” and “Obtain DNS server address automatically”. Your PC will search out a DHCP server and be assigned the address settings necessary to communicate on the network.
It is possible to display the IP configuration settings on a Windows PC by using the ipconfig command at the command prompt. The output will show the IPv4 address, subnet mask, and gateway information received from the DHCP server.
Use the Syntax Checker in Figure 2 to practice displaying the IPv4 address on a Windows PC.
Switch Virtual Interface Configuration
To access the switch remotely, an IP address and a subnet mask must be configured on the SVI. To configure an SVI on a switch, use the interface vlan 1 global configuration command. Vlan 1 is not an actual physical interface but a virtual one. Next assign an IPv4 address using the ip address ip-address subnet-mask interface configuration command. Finally, enable the virtual interface using the no shutdown interface configuration command.
After these commands are configured, the switch has all the IPv4 elements ready for communication over the network.
Click Play in the figure to view a video demonstration of how to configure a switch virtual interface.
Interface Addressing Verification
In the same way that you use commands and utilities like ipconfig to verify a PC host’s network configuration, you also use commands to verify the interfaces and address settings of intermediary devices like switches and routers.
Click Play in the figure to view a video demonstration of the show ip interface brief command. This command is useful for verifying the condition of the switch interfaces
