Configuring Network Devices
Working at a Small-to-Medium Business or ISP – Chapter 5
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Objectives
Configure a router with an initial configuration.
Use Cisco SDM to configure a Cisco ISR with LAN connectivity, Internet connectivity and basic NAT Configure a Cisco router for LAN connectivity, Internet connectivity and NAT using the Cisco IOS CLI of the Cisco IOS software Configure a WAN connection from a customer premise to an ISP. Describe, setup and configure a stand-alone LAN switch
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Configure a New ISR
Identifying the key components on a Cisco ISR
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Integrated Services Routers
The Cisco Integrated Services Router (ISR) is one of the most popular series of networking devices designed to support growing business needs. The ISR combines features such as routing and switching functions, security, voice, LAN and WAN connectivity into a single device.
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Cisco IOS Software
The Cisco Internetwork Operating System (IOS) software provides features that enable a Cisco device to send and receive network traffic using a wired or wireless network. IOS software is offered to customers in modules called images. These images support various features for businesses of every size. The entry-level Cisco IOS software image is called the IP Base image. There are many different IOS images available, as well as different versions of each image. These images are designed to operate on specific models of routers, switches and ISRs.
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Configure a New ISR
Procedures to physically set up a new Cisco ISR
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Physical set up a Cisco ISR
To install a new Cisco 1841 ISR requires special tools and equipment, which most ISPs and technician labs usually have available.
Typically, the tools required to install a new device include:
–PC with a terminal emulation program, such as HyperTerminal –Cable ties and a No. 2 Phillips screwdriver
–Cables for WAN interfaces, LAN interfaces, and USB interfaces
It is also necessary to have equipment and devices required for connection to WAN and broadband communication services, such as hubs or modems.
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In-band and Out-of-band Management Router Configuration
There are two possible methods to connect a PC to a network device for configuration and monitoring tasks: inband and out-of-band management. Out-of-band Management
–Out-of-band management requires a computer to be directly connected to the console port or auxiliary port (AUX) of the network device being configured. –This type of connection does not require the local network connections on the device to be active.
–Out-of-band management is used to initially configure a network device, because until properly configured, the device cannot participate in the network.
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In-band and Out-of-band Management Router Configuration
In-band Management –In-band management is used to monitor and make configuration changes to a network device over a network connection. –In order for a computer to connect to the device and perform in-band management tasks, at least one network interface on the device must be connected to the network and operational. –Two TCP/IP protocols can be used to access a Cisco device for in-band management: Telnet and HTTP.
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Cisco IOS Programs
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Cisco IOS Programs
The Cisco IOS Command Line Interface (CLI) is a text-based program that enables the entering and executing of Cisco IOS commands to configure, monitor, and maintain Cisco devices. Use CLI commands to alter the configuration of the device and to display the current status of processes on the router. There are other tools available to assist in configuring a Cisco router or ISR. –Cisco Router and Security Device Manager (SDM) is a graphical user interface (GUI) device management tool. Unlike CLI, SDM can be used only for in-band management tasks.
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Device Configuration Files
Running Configuration File –The term running configuration refers to the current configuration running on the device.
–It contains the commands used to determine how the device operates on the network. The running configuration is stored within the device working memory. –The device working memory is a type of random access memory (RAM) that does not keep information when the power is turned off. –Unless the running configuration is saved to the startup configuration file, its lost each time the device is shut down
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Device Configuration Files
Startup Configuration File –The startup configuration file is the saved configuration file that sets the configuration properties of the device each time the device is powered on. –This file is stored in nonvolatile random access memory (NVRAM).NVRAM is used to store files that will be saved, even if power to the device is turned off.
–Cisco CLI uses the command copy running-config startup-config to save the router's running configuration to the startup configuration.
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Configure a Cisco router using the Cisco IOS CLI
The role of the CLI in the Cisco IOS and different modes
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CLI and Modes
Using the Cisco IOS CLI to configure and monitor a device is very different than using the SDM.
CLI Command Modes
–The Cisco IOS supports two levels of access to the command-line interface: user EXEC access and privileged EXEC access.
–The user EXEC mode is indicated by a commandline prompt: Router> –Commands that can be executed in user EXEC mode are limited to obtaining information about how the device is operating and troubleshooting using ping or traceroute.
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CLI and Modes
To alter the operation of the device requires privileged level access. The prompt for the privileged mode is Router#.
The privileged EXEC mode is enabled by entering enable at the command prompt and pressing Enter. Both the user EXEC mode and the privileged EXEC mode can be protected with a password, or a username and password combination.
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CLI and Modes
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CLI and Modes
Configuring a Cisco IOS device begins with entering the privileged EXEC mode. The privileged mode grants access to the various configuration modes used to set up the device. Commands will be configured to the running configuration file from the terminal. To access these commands, the user must enter global configuration mode. To enter global configuration, type the command: configure terminal or config t. Global configuration mode is indicated by the command line prompt Router(config)#.
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Configure a Cisco router using the Cisco IOS CLI
Navigating the Cisco IOS CLI and performing basic setup configuration.
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Basic Configuration
The startup configuration file is stored on the device in NVRAM. To view the contents of the startup configuration file, use the command: Router#show startup-config The running configuration is the set of commands that is currently active in the device RAM. To view the current running configuration use the command: Router#show running-config To copy the changes made to the running configuration back to the stored startup configuration file, use the command: Router#copy run start
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Basic Configuration
The initial configuration of an IOS device involves configuring a device name and then the passwords that are used to control access to the various functions of the device. This task is accomplished in global configuration mode with the following command: Router(config)#hostname [name] Once a hostname is configured on a device, the next configuration step should be configuring passwords to prevent access to the device by unauthorized individuals.
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Basic Configuration
The enable password and enable secret commands are used to restrict access to the privileged EXEC mode, The following commands are used to set the passwords: Router(config)#enable password [password ] Router(config)#enable secret [password ] There are multiple ways to access a device to perform configuration tasks. One of these ways is to use a PC attached to the console port on the device. To set the password for console connection access, first enter the global configuration mode. Once there, use the following command:
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Basic Configuration
–Router(config)#line console 0 –Router(config-line)#password [password]
–Router(config-line)#login
This will prevent unauthorized users from accessing user mode from the console port.
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Configure a Cisco router using the Cisco IOS CLI
Configure serial and Ethernet interfaces on a router
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Configuring interfaces on a router
In order for a router to direct traffic from one network to another, the interfaces on the router are configured to participate in each of the networks. A router interface connects to a network and has an IP address and subnet mask assigned to it that is appropriate for that network.
There are many different types of interfaces available that is Serial and Ethernet interfaces.
Local network connections use Ethernet interfaces and WAN connections require the use of a serial connection through a TSP.
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Configuring interfaces on a router
Serial interfaces require a clock signal to control the timing of the communications, this is known as a clock rate.
In most environments, Data Communications Equipment (DCE) devices such as a modem, or CSU/DSU, provides the clock rate. By default, Cisco routers are DTE devices, or Data Terminal equipment. This means that they accept the clock rate from the DCE device.
A Router can be configured as a DCE device, if necessary. If the router is connected as the DCE device, a clock rate must be set on the router interface to control the timing of the DCE/DTE connection.
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Configuring interfaces on a router
To configure any interface on the router, it is necessary to be in the global configuration mode. The steps to configure an interface include:
1. Specify the type of interface and the interface port number 2. Specify a description of the interface 3. Configure the interface IP address and subnet mask
4. Set the clock rate, if configuring a serial interface as a DCE
5. Enable the interface
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Backing up a Router Configuration
Perform backup and system restore using a TFTP server
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Backing up a Router Configuration- with TFTP
Once a router is configured, the running configuration should be saved to the startup configuration file. It is also a good idea to save the configuration file in another location, such as a network server. Configuration files can be saved to a network server using the TFTP protocol. The TFTP enabled server must be accessible to the router via a network connection.
Restore To restore the backup configuration file, be sure the router has at least one interface configured and can access the TFTP server over the network.
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Initial Cisco 2960 Switch Configuration
Identifying the key components on a Cisco Catalyst 2960 Series Switch
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Switches
A switch is a device that is able to direct a stream of messages coming in one port, out of another port based on the destination MAC address within the frame. A switch cannot route traffic between two different local networks. In the context of the OSI model, a switch performs the Layer 2, known as the data-link layer function. Each switch port can operate in either half-duplex or full-duplex mode. –Half-duplex mode, a port can either send or receive data but not both. –Full-duplex mode, a port can simultaneously send and receive data, doubling the throughput.
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Switches
Both the port and the connected device must be set to the same duplex mode. If they are not the same, this creates a duplex mismatch and can lead to excessive collisions and degrade communication. Switch ports can have the speed and duplex set manually or can use auto negotiation.
–Auto negotiation occurs when the port can auto-detect the speed and duplex of the device that is connected to the port.
–For autonegotiation to be successful, both connected devices must support it.
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Initial Cisco 2960 Switch Configuration
Performing basic physical set up of a stand-alone LAN switch
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Switch set up on a LAN
The Cisco switch is supported by Cisco IOS switch software. The Cisco switch IOS image choices are similar to software images available on the Cisco ISR router. There are multiple options available to configure and manage a Cisco LAN switch. These options include:
•Cisco IOS Command Line Interface (CLI) •Cisco Network Assistant •Cisco Device Manager •CiscoView Management Software •SNMP Network Management Products
Some of these options use IP connectivity or a web-browser to connect to the switch, this requires the use of an IP address. Unlike router interfaces, switch ports are not assigned IP addresses. 34
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Initial Cisco 2960 Switch Configuration
How a switch can be managed using a management network interface (VLAN1)
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Initial Switch Configuration
The Cisco Catalyst 2960 switch comes preconfigured and only needs to be assigned basic security information before being connected to the network. The commands to configure hostname and passwords on the switch are the same commands used to configure the ISR. There is one Virtual Local Network, VLAN 1, preconfigured in the switch to provide access to management functions. –To configure the IP address assigned to the management interface on VLAN 1, enter global configuration mode. Switch>enable Switch#configure terminal
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Installing Customer Premise Equipment (CPE)
Network devices installed at the customer location are called customer premise equipment (CPE). Before any equipment is installed at the customer site, the devices are configured and tested at the ISP site. When installing customer equipment, it is important to complete the job in a professional manner. This means that all network cables are labeled and fastened together or run through proper cable management equipment. Installation Documentation When customer equipment is configured and installed on the customer premise, it is important to document the entire process.
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Customer connections over a WAN
WAN connections come in a variety of different types. WAN connections vary in the type of connector used, in bandwidth and in cost.
There are three types of serial WAN connections.
–Point-to-Point •A point-to-point WAN connection is a predefined communications path from the customer premises through a telecommunications service provider (TSP) network. •Point-to-point lines are usually leased from a TSP. These lines are often called leased lines. –Circuit Switched A circuit switched connection functions similarly to the way a phone call is made over a telephone network.
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Customer connections over a WAN
Packet Switched
–In a packet switched WAN connection, networks have connections into the TSP switched network.
–Each customer has their own virtual circuit.
•A virtual circuit is a logical path between the sender and receiver, not a physical path. An example of a packet switched network is Frame Relay.
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Choosing a WAN Connection
The WAN connection choice made is largely dependent on the bandwidth and cost of the connection. Availability for the higher bandwidth WAN connections can be limited in geographically isolated locations.
Another factor that affects the decision on which WAN to choose is the nature of how the business plans to use the new WAN connection. If the business provides services over the Internet, it may require higher upstream bandwidth than a business that uses services hosted by ISPs on the Internet.
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Summary
The Integrated Services Router (ISR) is a good choice for small to medium businesses and ISP-managed customers. ISRs can be initially configured using SDM or the router IOS CLI.
When using the CLI, “show” commands verify configuration elements.
Switches are assigned IP addresses by configuring them on the management interface, VLAN 1.
An installation plan can minimize disruption to a network when new devices are being added.
Good safety practices must be following when performing installations, to minimize the danger to both technician and device.
Documentation is necessary, both when configuring and when installing network devices.
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