basics to configure nw device

© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE I Chapter 6 1

Chapter Eleven

Configuring and Testing Your Network

Haitham A. El-Ghareeb2009 / 2010

© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 2

Cisco IOS

Network Device cannot function without an Operating System.

Cisco Internetwork Operating System (IOS) is the system software in Cisco Devices

Cisco IOS provides devices with the following network services:

–Basic routing and switching functions

–Reliable and secure access to networked resources

–Network scalability

Services provided by Cisco IOS are generally accessed using Command Line Interface (CLI)


Cisco IOS (Cont.)

IOS file is several megabytes in size and is stored in a semi permanent memory area called Flash.

Flash memory provides non-volatile storage.

Using flash memory allows IOS to be upgraded to newer versions or to have new features added.

In many router architectures, IOS is copied into RAM when the device is powered on and the IOS runs from RAM. This function increases the performance of the device.


Cisco IOS (Cont.)


Cisco IOS Access Methods

Most Usual Methods–Console

–Telnet or SSH

–AUX Port


Cisco IOS Access Methods (Cont.)

Console–Also known as CTYCTY Line

–Uses low speed serial connection to directly connect a computer or terminal to the console port

–Management port that provides out-of-band access to the router

–Accessible even if NO networking services have been configured

–Often used to access a device when the networking services have not been started or have failed

–Examples of console use are:

•Initial configuration

•Disaster recovery

•Password Recovery

–By default, the console conveys the device startup, debugging, and error messages

–The device should be located in a locked room or requirement rack to prevent physical access



Telnet and SSH–A method for RemotelyRemotely accessing a CLI session

–Require active networking serviceactive networking service (at least on active interface configured with Layer 3 Address)

–Cisco IOS include a Telnet Server ProcessTelnet Server Process, and a Telnet ClientTelnet Client

–Secure Shell (SSH) Secure Shell (SSH) protocol is a more SecureSecure method

–As a best practice, always use SSH in place of TelnetAs a best practice, always use SSH in place of Telnet

–IOS Devices also include SSH ServerServer and ClientClient



AUX (Auxiliary)–Establish a CLI Session remotely via a telephone dialup connection using a modem connected to the router’s AUX port

–Doesn’t require any networking services to be configured

–Can also be used locally; like console port

–Not all routers have AUX port

–Console is preferred over AUX in troubleshooting because it displays router startup, debugging, and error messages by default

–The only time AUX is used locally instead of the console port is when there are problems using console port


Configuration Files

Network Devices depend on two types of software for their operation:

–Operating System:Operating System: facilitates the basic operation of the device’s hardware components

–Configuration Files: Configuration Files: contain Cisco IOS software commands used to customize functionality of the device. Commands are parsed by Cisco IOS

Types of Configuration Files–Running Configuration File: Running Configuration File: used during the current operation of the device | Changes will immediately affect the operation, RAM

–Startup Configuration File:Startup Configuration File: used as the backup configuration and is loaded when the device is started (Stored in NVRAM)


Cisco IOS Modes

IOS is a modal OS. Major Modes are:–User Executive Mode

–Privileged Executive Mode

–Global Configuration Mode

–Other specific configuration Mode


IOS Primary Modes

User EXEC Mode Privileged EXEC Mode

Allows only a limited no. of basic monitoring commands

Execution of configuration and management

commands

Doesn’t allow execution of any commands that might

change the device’s configuration

Debugging, Testing

The entrance of the CLI The Higher Level

Doesn't require Authentication

By default, doesn't require authentication

Identified by the prompt> Identified by the prompt#


Basic IOS Command Structure


Using CLI Help (1)

Context Sensitive Help


Using CLI Help (2)

Command Syntax Check


IOS “Examination” Commands


Router#Show version

Software Version, Bootstrap Version, System up-time, System restart info, Software image name, Router Type and Processor

type, Memory type and allocation (Shared/Main), Software Features, Hardware Interfaces, Configuration Register


Other Show Commands

Command Function

show arp Displays the ARP table of the device

show mac-address-table Displays the MAC table of a switch

show startup-config Displays the saved configuration located in NVRAM

show running-config Displays the contents of the currently running configuration file or

the configuration for a specific interface, or map class information.

show ip interfaces Displays IPv4 statistics for all interfaces on a router

Show ip route Displays the next hop and checks its status


IOS Configuration Modes


Configuring IOS: Host Name


Limiting Device Access – Configure Passwords

Every device shall have locally configured passwords to limit access

The passwords introduced here are:–Console Password

–Enable Password

–Enable Secret Password

–VTY password


Console Password

Switch(config)#line console 0

Switch(config-line)#password password

Switch(config-line)#login


Telnet and Password Encryption


Login Banner


Show Running Configuration


Backing Up Configuration Offline


Removing All Configuration

Router#erase startup-config

Router#Reload

Caution: Caution: Exercise care when using the erase command. This command can be used to erase any file in the device. Improper use of the command can erase the IOS itself or another critical file


Configure Router Interfaces


Configure Router Ethernet


Configure Router Serial Interface


Router Interfaces Description


Switch Interface VLAN

Important for Management

Needed on the Switches to Ping and Telnet Routers


Testing Interface Assignment


Testing Local Network


Testing Gateway Connectivity


Putting it all Together

Test 1: Local Loop

Test 2: Local NIC

Test 3: Ping Local Gateway

Test 4: Ping Remote Host – Failure

Test 5: Traceroute to Remote Host – Failure at First Hop

Test 6: Examine Host Configuration for Proper Local Gateway

Display Figure


Basic Network Baselines A Network BaselineA Network Baseline is a Process that involves monitoring

network performance and behavior over a certain period of time allowing for a point of reference when wanting to monitor performance in the future.

One methodmethod for starting a baseline is to copy and paste the results from an executed ping, trace, or other relevant command into a text file. These text files can be time stamped with the date and saved into an archive for later retrieval.

The importanceimportance of creating documentation cannot be emphasized enough. Verification of host-to-host connectivity, latency issues, and resolutions of identified problems can assist a network administrator in keeping a network running as efficiently as possible.


Learning About the Nodes on the Network

arp command lists all devices currently in the ARP cache. The cache can be cleared by using the arp –d

Ping Sweep


Switch Connections


Lab Test

Perform the Basic Configurations for Router / Switch–Authenticate Executive Privileged Mode via Clear and Encrypted Passwords

–Authenticate CTY, VTY

–Create the suitable Log-in and MOTD Banners

–Apply the Address Schema given to you in the Exam Paper

Verify Connectivity, Debug and Correct the Issues

HTTP and DNS Activity

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