Data Communications & Networks

Introduction to Cisco Router

UCCN 1003 (May 2010)

(Lecture 03b)

Purpose of a Router

• The basic purpose of a router

– Computers that specialize in sending packets over the

data network.

– They are responsible for interconnecting networks by

selecting the best path for a packet to travel and forwarding packets to their destination

Hardware Component of a Cisco Router

• Router components and their functions”– CPU - Executes operating system instructions

– Random access memory (RAM) - Contains the running copy of configuration file. Stores routing table. RAM contents lost when power is off

– Read-only memory (ROM) - Holds diagnostic software used when router is powered up. Stores the router’s bootstrap program.

– Non-volatile RAM (NVRAM) - Stores startup configuration. This may include IP addresses (Routing protocol, Hostname of router)

– Flash memory - Contains the operating system (Cisco IOS)

– Interfaces - There exist multiple physical interfaces that are used to connect network. Examples of interface types:

• Ethernet / fast Ethernet interfaces

• Serial interfaces

• Management interfaces

Hardware Component of a Cisco Router

Checking Router with “show version”

Router Models in Packet Tracer 5.3

• There are 4 router models In Packet Tracer 5.3:

– 1841

– 2620XM

– 2621XM

– 2811

• In packet tracer, 4 models obviously differ in:

– number and type of “slots” that extra

communication modules can be added in.

Cisco 1841 Router

1841

• The Cisco 1841 Integrated Services Router provides: – two fixed 10/100 (100BASE-TX) Ethernet ports,

• Interface name fa0/0, fa0/1

– two integrated High-Speed WAN Interface Card (HWIC) slots that are compatible with WAN Interface Card (WICs)

• WAN = Wide Area Networks

HWIC slot #1 HWIC slot #22 FastEthernet ports

Flash memory slot

Cisco 2620XM Router

2620XM

• The Cisco 2620XM Multiservice Router provides – one fixed 10/100 (100BASE-TX) Ethernet port,

– two integrated WAN Interface Card (WIC) slots,

– one Advanced Integration Module (AIM) slot.

WIC slot #2

FastEthernet port

WIC slot #1AIM slot

Cisco 2621XM Router

• The Cisco 2621XM Multiservice Router provides – two fixed 10/100 (100BASE-TX) Ethernet ports,

– two integrated WAN Interface Card (WIC) slots,

– one Advanced Integration Module (AIM) slot.

2621XM

WIC slot #2

2 FastEthernet ports

WIC slot #1AIM slot

Cisco 2811 Router

• The Cisco 2811 Integrated Services Router provides – two fixed 10/100 (100BASE-TX) Ethernet ports, – four integrated High-Speed WAN Interface Card (HWIC) slots that

are compatible with WAN Interface Card (WICs), – Advanced Integration Module (AIM) slot.

2811

4 HWIC slots2 FastEthernet ports

AIM slot

Flash memory slot

Router Interfaces

• Router Interface is a physical connector that enables a router to send or receive packets

• Each interface connects to a separate network

• Consist of socket or jack found on the outside of a router

• Types of router interfaces:– Ethernet

– Fastethernet

– Serial

– DSL

– ISDN

– Cable

Cisco Modules for HWIC & WIC Slots

• HWIC-4ESW– provides four switching ports.

• HWIC-AP-AG-B– It supports Single Band 802.11b/g or Dual Band 802.11a/b/g radios.

• WIC-1AM– features dual RJ-11 connectors, which are used for basic telephone service

connections. The WIC-1AM uses one port for connection to a standard telephone line, and the other port can be connected to a basic analog telephone for use when the modem is idle.

• WIC-1ENET– is a single-port 10 Mbps Ethernet interface card, for use with 10BASE-T Ethernet LANs.

• WIC-1T– provides a single port serial connection to remote sites or legacy serial network devices

• WIC-2AM– features dual RJ-11 connectors, which are used for basic telephone service

connections. The WIC-2AM has two modem ports to allow multiple data communication connections.

• WIC-2T– The 2-port asynchronous/synchronous serial network module provides flexible multi-

protocol support, with each port individually configurable in synchronous or asynchronous mode,

Cisco Modules for AIM Slots

• NM-1E– features a single Ethernet port that can connect a LAN backbone which

can also support either six PRI connections to aggregate ISDN lines, or 24 synchronous/asynchronous ports.

• NM-1E2W– provides a single Ethernet port with two WIC slots that can support a

single Ethernet LAN, together with two serial/ISDN backhaul lines, and still allow multiple serial or ISDN in the same chassis.

• NM-1FE-FX– provides one Fast-Ethernet interface for use with fiber media.

• NM-1FE-TX– provides one Fast-Ethernet interface for use with copper media.

• NM-1FE2W– provides one Fast-Ethernet interface for use with copper media, and two

WIC expansion slots.

Cisco Modules for AIM Slots

• NM-2E2W– provides two Ethernet ports with two WIC slots that can support two

Ethernet LANs, together with two serial/ISDN backhaul lines, and still allow multiple serial or ISDN in the same chassis.

• NM-2FE2W– provides two Fast-Ethernet interfaces for use with copper media, and two

WIC expansion slots.

• NM-4A/S– The 4-port asynchronous/synchronous serial network module.

• NM-4E– four Ethernet ports.

• NM-8A/S– The 8-port asynchronous/synchronous serial network module

• NM-8AM– The NM-8AM Integrated V.92 analog modem network module provides

eight RJ-11 jacks to connect the integrated modems to basic analog telephone lines on the public switched telephone network (PSTN) or private telephony systems.

Flash and NVRAM

• Flash and NVRAM act like the “hard disk” of the Cisco router.

• In Cisco router, flash memory is used to store the images of the IOS and NVRAM is used to store the startup configuration file.

• NVRAM provide much faster read/write than flash, but is more costly.

• Extra flash can be added to the “flash memory slot” of the router.

• The following command “show file systems” shows the memory size of both flash and NVRAM in a typical 1841 router.

– 64M for flash, 30k for NVRAM

Cisco IOS

• Similar to a personal computer, a router cannot

function without an operating system.

• The Cisco Internetwork Operating System (IOS) is

the system software in Cisco devices.

• The Cisco IOS provides devices with the following

network services:

– Basic routing functions

– Reliable and secure access to networked resources

– Network scalability

Command Line Interface (CLI)

• The services provided by the Cisco IOS are generally accessed using a command line interface (CLI).

• CLI is the “place” where you put in the commands in order to perform the router configuration such as:– Setting IP address for router ports.

– Setting routes

– Showing routers statistics

Note:

In real life, the router CLI is not as

“easily” accessible as in the Packet

Tracer by just clicking on a tab.

Flash and IOS Image

• Type “show flash:” to display the memory content of the flash which includes the IOS image.

• IOS on different router will have its own specific image for the router.

IOS Image

Accessing CLI

• There are 3 ways to access the CLI environment.

– Console

– Telnet or SSH

– AUX port

Accessing CLI – Console port

• You need 2 items + 1 software to access the CLI via the console port– PC,

– Rollover Cable

– Comm software (e.g. HyperTerminal),

• Rollover cable is a cable with a serial comm connect at one end, and a RJ-45 connector at the other end.

• Rollover connects the serial comm port of a PC to the console port of a router.

Accessing CLI – Console port

• The console port is often used to access a router – when the networking services have not been started or have failed.

– When a router is first placed into service, networking parameters have not yet been configured yet.

– The initial configuration of the network device

– Disaster recovery procedures and troubleshooting where remote access is not possible

– Password recovery procedures

• Accessing CLI through console port can’t be done remotely (from a far)– One has to be done next to the router with a PC/laptop

Accessing CLI – Console port - 3

• HyperTerminal in Windows XP is the software that

you can use to access the CLI environment.

– You can set the HyperTerminal Configuration as shown

No DHCP or Data via Console

• Rollover cable via console port is NOT for network purposes, hence for PC0: – don’t need an IP to perform configuration

– can’t obtain DHCP or dynamic IP

– can’t access web pages

– can’t download files

– can’t access any network services

Rollover cable

Accessing CLI Remotely – Telnet & Aux

• Two ways to access CLI for “afar” or remotely:– Aux port

• via a telephone dialup connection using a modem connected to therouter's AUX port.

• Similar to the console connection, this method does not require any networking services to be configured or available on the device.

• The AUX port can also be used locally, like the console port, with a direct connection to a computer running a terminal emulation program.

– telnet• via the networking ports (FastEthernet Ports: e.g. fa0/0, Ethernet ports,

serial ports).

• Telnet service has to be setup via the console port first.

• Will be explored in the lab.

AuxTelnet Telnet Telnet

Router CLI mode

• CLI mode = prompt• Different mode accepts different set of commands

• Just remember= different prompt cater for different commands

Privilege and User Mode

• User mode can only access limited commands

– Prompt ‘>’

– Can use “show” commands

– Can’t make configuration which changes the router.

• Privilege mode is where you can enter commands

that can configure the router

– Prompt ‘#’

– Only after the command “enable” you can start to enter

other commands that can make changes to the router.

CLI Command Hierarchy

• The prompts has a form of “hierarchy”, meaning you have to go through other “prompts”first before you reach the “desired” prompt.

• For example: in order to reach “Router(config-if), you have to go through 2 more prompts first:

– Router>enable

– Router#config terminal

– Router(config)#int fa0/0

– Router(config-if)#

Right Command at the right prompt

• You have to be in the right “prompt” before a command can be “accepted”.

• In router CLI, not only you need to memorize the commands (and their effect), but also the “correct prompt” that you key in the command.

• So beware of the prompt (or CLI mode) when you configure the Cisco router.

Router>int fa0/0

^

% Invalid input detected at '^' marker.

Router>en

Router#int fa0/0

^

% Invalid input detected at '^' marker.

Router#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#int fa0/0

Router(config-if)#

Commands

at the “wrong”

prompt.

Router Commands Hot-Keys

Shortcuts for entering commands

• You do not need to type in the “full phrase” for that particular command to take effect.– Type “show interface” = “show int” = “sh int”– Type “configure terminal” = “config t” = “conf t”

• However, the short form can’t be too short.– Type “sh i” for “show int” won’t work.

– At least 2 characters and above for 1 word (e.g in = interface)

Some Examples of Cisco Commands

Turn on Telnet Service with Password

• In order for you to “remotely” telnet into the router via the data ports (e.g. fa0/0)

• The following shows the commands that turn on the telnet service of the router.– vty = ( Virtual TeletYpe), treat this as telnet

– 0 4 = accepting channel 0 to channel 4, concurrently 5 telnet users can log in.

uccn1003#conf t

uccn1003(config)#line vty 0 4

uccn1003(config-line)#password <password>

uccn1003(config-line)#login

uccn1003(config-line)#end

uccn1003#

Running-configuration

• The active configuration file of the router.

• Stored in RAM– If the power is turned-off, the

running-configuration will be GONE.

• Command “show run”.– You need to view the

running-config in order to troubleshoot the router.

Choo#show run

Building configuration...

!

version 12.4

!

hostname Choo

!

enable password uccn1003

interface FastEthernet0/0

ip address 192.168.1.254 255.255.255.0

!

interface FastEthernet0/1

no ip address

shutdown

!

interface Vlan1

no ip address

shutdown

!

line con 0

line vty 0 4

password network

login

!

end

Choo#

Startup-configuration

• Stored in NVRAM.

• Load in as running-config during the router startup.

• Command for viewing the startup-config: “show start”

• Backing up running-config in startup-config: “copy run start”– Note, when you turn off switches or

routers and then turn them back on, they will load their startup configuration files.

– If you do not backup the running configuration, it will be lost.

Choo#show start

startup-config is not present

Choo#copy run start

Destination filename [startup-config]? Building configuration...

[OK]

Choo#show start

Using 508 bytes!

version 12.4

!

hostname Choo

!enable password uccn1003

!

interface FastEthernet0/0

ip address 192.168.1.254

255.255.255.0!

interface FastEthernet0/1

no ip address

shutdown

!end

Voiding or Canceling commands

• To remove a command from the configuration, simply go to the proper location or prompt and type "no" followed by the command to be removed.

• The following example show – How to remove hostname

– How to remove enable password

– How to remove an IP address in int fa0/0

– Please compare the running-config on the right, with the running-config at the previous two slides.

Choo#

Choo#conf t

Choo(config)#no hostname Choo

Router(config)#no enable password

Router(config)#int fa0/0

Router(config-if)#no ip address

Router(config-if)#

Router#show run

Building configuration...

!

version 12.4

!

hostname Router

!

interface FastEthernet0/0

no ip address

!

interface FastEthernet0/1

no ip address

shutdown

!

line con 0

line vty 0 4

password network

login

!

end

Case Study – Module & Interface

• Case study:– Router 1 is planned to connect to 6 other LANs

– 3 fast Ethernet

– 1 serial connection

– 1 telephone modem

– 1 Ethernet

• Problem:– Router 2811 originally only has 2 fixed fast Ethernet port

• FastEthernet0/0 and FastEthernet0/1

Case Study – Module & Interface

• Solution: Add modules– Add module NM-2FE2W in AIM slot

• 2 FastEthernet ports with 2 WIC slots

– Add module WIC-1AM in HWIC slot• Telephone Model

– Add module WIC-1ENET in HWIC slot• 1 Ethernet port

– Add module WIC-1T in HWIC slot• Serial connection

Case Study – Module & Interface

• Comments:– Know the “names” of the modules in order to

access them.

– If the modules does not exist, you can’t access them.

• Accessing the modules in CLI– In real life use, commands “show ip int brief” to

learn the existence of the modules or interfaces.

– int Serial0/3/0

– int FastEthernet1/0

– int FastEthernet1/1

– Refer to the following example:

Original

Added

Conclusion

• You have been shown the basic overview of Cisco Router– Cisco IOS

– Cisco CLI and how to access it

– Console port and rollover cables

– CLI modes and prompts

– Some simple cisco commands

– Running-config & startup-config

– Modules and interfaces.

• We will continue to learn other Cisco router commands in the Lab.

Quiz

MCQ

• Which of the following is a common use of the telnet utility? – A) Checking Network Status

– B) Remote administration

– C) Accessing Web D) Troubleshooting

– E) Downloading F) Email

• The console port is used for_________?– A) telneting B) phone line HyperTerminal

– C) password recovery D) ipconfig

– E) passing data between routers F) troubleshooting

– G) downloading files H) examine configuration files

Answer

• Answer: A, B, D

• Answer: C, F, H

MCQ

• Which command(s) turns the power on in a router interface (such as fa0/0)?– A) Router(config)#no shutdown

– B) Router(config)#int fa0/0 on

– C) Router(config-if)#int enab

– D) Router(config-if)#no sh

– E) Router(config-if)#no shut

– F) Router(config-if)#no down

– G) Router#int fa0/0 on

– H) Router(config-if)#enable

• You are configuring a Cisco router. You want to configure the IP address on an interface. Which command should you use?

– A) Router(config-if)#ip address 142.8.2.1 subnet mask 255.255.252.0

– B) Router(config)#142.8.2.1 0.0.3.255

– C) Router#ip address 142.8.2.1 255.255.252.0

– D) Router(config-if)#142.8.2.1 subnet mask 255.255.252.0

– E) Router(config-if)#ip address 142.8.2.1 0.0.3.255

– F) Router(config)#ip address 142.8.2.1 255.255.252.0

Answer

• Answer: D, E

• Answer: None