ICND I (100-101) 07 - Installing & Operating Cisco LAN Switches.pptx

By Muhammad Asghar Khan

[email protected]

07 - Installing & Operating Cisco LAN Switches

Reference: Cisco CCENT/CCNA ICND1 100-101 Official Cert Guide By WENDELL ODOM

© Cisco Press

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Agenda

www.asghars.blogspot.com

IntroductionCisco Catalyst Switch BrandCisco Linksys Switch Brand

The Cisco Catalyst 2960 SwitchSwitch Status from LEDs

Accessing the Cisco IOS CLICLI Access from the ConsoleCLI Access with Telnet & SSHSetting Password Security for CLI

Cisco IOS Modes of OperationUser EXEC ModePrivileged EXEC Mode

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Agenda


Global Configuration Mode

Switch Configuration FilesTypes of Switch Memory

RAM/DRAM ROM Flash Memory NVRAM

Types of Configurations Initial Configuration (Setup Mode) Startup Configuration Running Configuration

Copying Configuration FilesErasing Configuration Files

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Introduction


Cisco has two major brands of LAN switching productsCisco Catalyst Switch Brand

Includes a large collection of switches, all of which have been designed with Enterprises in mind

The Catalyst switches have a wide range of sizes, functions, and forwarding rates

Cisco Linksys Switch Brand Includes a variety of switches designed for use in the home

The CCNA exams focus on how to implement LANs using Cisco Catalyst switches

Both the Catalyst and Linksys brands of Cisco switches provide the same base features

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Introduction


Within the Cisco Catalyst brand, Cisco produces a wide variety of switch series or families

Each switch series includes several specific models of switches that have:Similar Features, Similar Price-Versus-Performance trade-offs, andSimilar Internal components

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The Cisco Catalyst 2960 Switch


Cisco positions the 2960 series/family of switches as full-featured, low cost wiring closet/cabinet switches for enterprises

2960 switches are mostly used as access switches

The distribution layer switches are often from a different Cisco switch family, typically a more powerful and more expensive product family

Figure on next slide shows the photo of the 2960 switch series from Cisco; each switch is a different specific model of switch inside the 2960 series

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Cisco Catalyst 2960 Series

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Three of the five switches have 48 RJ-45 10/100 ports, meaning that these ports can negotiate the use of 10BASE-T or 100BASE-TX Ethernet

These switches also have few additional RJ-45 ports on the right that are 10/100/1000 interfaces on the right, intended to connect to the core switches of an Enterprise campus LAN

Cisco refers to a switch’s physical connectors as either interfaces or ports. Each interface has a number in the style x/y, where x and y are two different numbers

In a 2960, the number before the / is always 0. The first 10/100 interface on a 2960 is numbered starting at 0/1, the second is 0/2, and so on

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The interfaces also have names; for example, “interface FastEthernet 0/1” is the first of the 10/100 interfaces

Any Gigabit-capable interfaces would be called “GigabitEthernet” interfaces

Cisco supports two major types of switch operating systems: Internetwork Operating System (IOS) Catalyst Operating System (Cat OS)

Most Cisco Catalyst switch series today run only Cisco IOS But for some historical reasons, some of the high-end Cisco

LAN switches support both Cisco IOS and Cat OS Cisco also uses the term hybrid to refer to 6500 switches

that use Cat OS and the term native to refer to 6500 switches that use Cisco IOS

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Switch Status from LEDsSwitch hardware includes several LEDs that

provide some status and troubleshooting information

Figure shows the front of a 2960 series switch, with five LEDs on the left, one LED over each port, and a mode button

SYST (System)

RPS (Redundant Power Supply)STAT (Status)

DUPLX (Duplex)SPEED

Port

MODE

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To make sense of the LEDs, consider the specific example of SYST LED SYST LED provides a quick overall status of the switch,

with three states on most 2960 switch models: Off: switch is not powered on On (green): switch is powered on and operational (Cisco

IOS has been loaded) On (amber): switch’s Power-On Self Test (POST) process

failed, and the Cisco IOS did not load. In this case, the typical response is to power the switch off and back on again. If the same failure occurs, a call to the Cisco Technical Assistance Center (TAC) is typically the next step

The particular details of how each LED works differ between different Cisco switch families and with different models inside the same switch family

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The port LEDs—the LEDs sitting above or below each Ethernet port—means something different depending on which of three port LED modes is currently used on the switch

The switches have a mode button (labeled with number 6 in Figure) that, when pressed, cycles the port LEDs through three modes: STATDUPLX, and SPEED

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Each of the three port LED modes changes the meaning of the port LEDs associated with each port In STAT (status) Mode

Off: The link is not workingSolid Green: The link is working, but there’s no current

trafficFlashing Green: The link is working, and traffic is currently

passing over the interfaceFlashing Amber: The interface is administratively disabled

or has been dynamically disabled for a variety of reasons In SPEED Mode

Dark LED; meaning 10 MbpsSolid Green Light; meaning 100 Mbps Flashing Green; meaning 1000 Mbps (1 Gbps)

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Accessing the Cisco IOS CLI


The command-line interface (CLI) is a text-based interface in which the user, typically a network engineer, enters a text command and presses Enter

Pressing Enter sends the command to the switch, which tells the device to do something

Cisco IOS not also define an interface (CLI) for humans but it also controls the switch’s performance and behavior

The switch CLI can be accessed through three popular methods—the console, Telnet, and Secure Shell (SSH)

The console is a physical port built specifically to allow access to the CLI

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Telnet and SSH use the IP network in which the switch resides to reach the switch

Figure on next slide shows the cabling

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Next, a terminal emulator software package (e.g. tera term) must be installed and configured to use the PC’s serial port, matching the switch’s console port settings

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The default console port settings on a switch are as

follows: 9600 bits/second No hardware flow control 8-bit ASCII No stop bits 1 parity bit

Figure shows the configuration window for the settings just listed

CLI Access with Telnet & SSHMost terminal emulator packages also include both

Telnet & SSH client functions

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Telnet or SSH application protocol calls the terminal emulator a “Telnet Client or SSH Client” and device that listens for commands is called “Telnet Server or SSH Server”

The switch runs Telnet and SSH server software by default, but needs to have an IP address configured

Telnet & SHH is TCP based where Telnet uses the port 23 and SHH uses the port 22

The key difference b/w Telnet & SHH is that Telnet sends all data as clear-text data, while the SHH sends data in more secure manner by using the encryption

By default switch allows only console access, but no Telnet or SHH access

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Cisco switches refers to console as console line-specifically, console line 0

Cisco switches also support 16 Telnet sessions, referenced as virtual terminal (vty) lines 0 through 15

SSH requires a little more effort than console & Telnet, as SSH uses public key cryptography to exchange a shared session key

Additionally, SSH requires both username and password for login

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Cisco IOS Modes of Operation


Cisco IOS provides access to several different command modes

Each command mode provides a different group of related commands

Entering a question mark (?) at the system prompt allows you to obtain a list of commands available for each command mode

The three basic modes are:User EXEC ModePrivileged EXEC ModeGlobal Configuration Mode

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User EXEC ModeIt is the default command mode for the CLI It is also called User ModeThe user EXEC commands allow you to connect

to remote devices, change terminal settings on a temporary basis, perform basic tests, and list system information

EXEC refers to the fact that the user only enter the command, switch executes that command and then display the message

The prompt for user EXEC mode is the name of the device followed by an angle bracket:

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Privileged EXEC ModePrivileged EXEC commands set operating parametersPrivileged EXEC mode is password protected It is also called simply privileged or enable modeTo enter privileged mode, enter the ”enable” EXEC

command from user EXEC mode:

To set enable mode password, use either the ”enable password” or ”enable secret” commands

It is recommended that you use the ”enable secret” command because it uses an improved encryption algorithm

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Use the ”enable password” command only if you boot an older image of the Cisco IOS software

Figure shows the User & Privileged modes

Global Configuration ModeGlobal configuration commands apply to features

that affect the system as a whole, rather than just one protocol or interface

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Commands entered in configuration mode update the active configuration file

Configuration mode itself contains submodesSubmodes used to configure specific system featuresContext-setting commands move you from one

configuration mode or context to anotherTo enter global configuration mode, enter

the ”configure” command from privileged EXEC mode:

The system prompt changes to indicate that you are now in global configuration mode

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Some of the sub-modes are:Access-list ConfigurationLine Configuration Interface Configuration

Access-list ConfigurationUse access-list configuration mode when you are

creating a named IP or IPX access listFrom global configuration mode, use the “ip access-list” or “ipx access-list” command

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Line configurationLine configuration commands modify the operation of

an auxiliary, console, physical, or virtual terminal lineFrom global configuration mode, enter by specifying

a line with a line {aux|con|tty|vty} line-number [ending-line-number] command

Interface ConfigurationThe commands entered in this mode modify the

operation of an interface From global configuration mode, enter by specifying

an interface with an interface command

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Figure shows the relationship b/w EXEC modes and configuration mode

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The end or Ctrl+z key sequence exit the user from any part of configuration mode and go back to privileged EXEC mode

While the exit command backs you out of configuration mode one sub-configuration mode at a time

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Switch Configuration Files


To work with files, you need some sort of memory Cisco switches uses several types of permanent memory

as:RAM/DRAM

Used by switch as it is used by any other computerROM

Stores bootstrap/boot-helper program, that is loaded when the switch first power on

Bootstrap program finds the image of IOS and load it into the RAM

Flash Memory Found in the form of chip inside the switch or a removable

memory card Stores the Cisco IOS images and it is the default location where

bootstrap searches for the IOS image

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It can also be used to store configuration or backup filesNonvolatile RAM (NVRAM)

Stores the initial or startup configuration file

A configuration file saves the switch configuration commands in text format

Switch maintains the following types of configuration: Initial Configuration (Setup Mode)

Setup mode leads a switch administrator to a basic switch configuration by using questions that prompt for basic switch configuration parameters

Figure on next slide describe the process used by setup mode

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Startup ConfigurationUsed for initialization when the switch boots If this file does not exist, the system boots using

the factory defaults

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It is stored in NVRAMYou can use the show startup-config command to view

the startup configuration fileThe IOS File System (IFS) refers to startup-config as

nvram:startup-configRunning Configuration

Stores the currently used configuration commandsThis file changes dynamically when someone enters

commands in configuration mode It is stored in RAM If the switch is reloaded (rebooted) and the running

configuration is not saved all commands will be lostYou can use the show running-config command to view

the startup configuration file

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The IOS File System (IFS)

refers to running-config

as system:running-config

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Copying Configuration FilesThe “copy” command can be used to copy files

b/w RAM or NVRAM on a switch and a TFTP serverThe copy command can be summarized as:

copy { tftp|running-config|startup-config }

{ tftp|running-config|startup-config }

It always replaces the existing configuration file when the file is copied into NVRAM or into a TFTP server, while it merged the configuration file into the running-config file in RAM

Figure on next slide depicts the locations and results of copy operation

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Erasing Configuration FilesYou can use three different commands to erase

the contents of NVRAMwrite erase (older)erase startup-config (older)erase nvram (recomened)

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All the three commands will erase the contents of the NVRAM configuration file

Note there is no command to erase the contents of the running-config file; to clear the running-config file, simply erase the startup-config file and then “reload” the switch

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ICND I (100-101) 07 - Installing & Operating Cisco LAN Switches.pptx

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