Routers are networking devices that interconnect networks by forwarding data packets between them using the best available path. The basic components of a Cisco router include a CPU, RAM, ROM, NVRAM, flash memory, and physical interfaces. The Cisco IOS operating system runs on routers and provides routing functions and network services via the command line interface. Different Cisco router models have varying numbers and types of slots to add communication modules.

1. UCCN 1003 (May 2010)
Data Communications & Networks
(Lecture 03b)
Introduction to Cisco Router

2. 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

3. 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

4. Hardware Component of a Cisco Router

5. Checking Router with “show version”

6. 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.

7. Cisco 1841 Router
• 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 2 FastEthernet ports HWIC slot #2
1841
Flash memory slot

8. Cisco 2620XM Router
• 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.
FastEthernet port
AIM slot WIC slot #1 WIC slot #2
2620XM

9. 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.
2 FastEthernet ports
AIM slot WIC slot #1 WIC slot #2
2621XM

10. 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.
AIM slot 2 FastEthernet ports
4 HWIC slots
2811
Flash memory slot

11. 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

12. 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,

13. 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.

14. 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.

15. 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

16. 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

17. 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.

18. 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

19. Accessing CLI
• There are 3 ways to access the CLI environment.
– Console
– Telnet or SSH
– AUX port

20. 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.

21. 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

22. 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

23. 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

24. 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 the
router'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.
Telnet Telnet Aux Telnet

25. Router CLI mode
• CLI mode = prompt
• Different mode accepts different set of commands
• Just remember= different prompt cater for different
commands

26. 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.

27. 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)#

28. 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
^
Commands
% Invalid input detected at '^' marker.
at the “wrong”
prompt.
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)#

29. Router Commands Hot-Keys

30. 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)

31. Some Examples of Cisco Commands

32. 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#

33. Running-configuration
Choo#show run
Building configuration...
• The active configuration file !
version 12.4
of the router. !
hostname Choo
• Stored in RAM !
enable password uccn1003
– If the power is turned-off, the interface FastEthernet0/0
running-configuration will be !
ip address 192.168.1.254 255.255.255.0
GONE. interface FastEthernet0/1
no ip address
• Command “show run”. shutdown
!
– You need to view the interface Vlan1
running-config in order to no ip address
shutdown
troubleshoot the router. !
line con 0
line vty 0 4
password network
login
!
end
Choo#

34. Startup-configuration
• Stored in NVRAM. Choo#show start
startup-config is not present
• Load in as running-config during Choo#copy run start
Destination filename [startup-config]?
the router startup. Building configuration...
[OK]
• Command for viewing the Choo#show start
Using 508 bytes
startup-config: “show start” !
version 12.4
• Backing up running-config in !
hostname Choo
startup-config: “copy run start” !
enable password uccn1003
– Note, when you turn off switches or !
interface FastEthernet0/0
routers and then turn them back on, ip address 192.168.1.254
they will load their startup 255.255.255.0
!
configuration files. interface FastEthernet0/1
no ip address
– If you do not backup the running shutdown
configuration, it will be lost. !
end

35. Voiding or Canceling commands
• To remove a command from the configuration, Router#show run
simply go to the proper location or prompt and Building configuration...
type "no" followed by the command to be
removed. !
version 12.4
• The following example show
!
– How to remove hostname hostname Router
– How to remove enable password !
– How to remove an IP address in int fa0/0 interface FastEthernet0/0
– Please compare the running-config on the right, no ip address
with the running-config at the previous two slides. !
interface FastEthernet0/1
no ip address
Choo# shutdown
Choo#conf t !
Choo(config)#no hostname Choo line con 0
line vty 0 4
Router(config)#no enable password
password network
Router(config)#int fa0/0 login
Router(config-if)#no ip address !
Router(config-if)# end

36. 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

37. 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

38. 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

39. 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.

40. Quiz

41. 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

42. Answer
• Answer: A, B, D
• Answer: C, F, H

43. 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

44. Answer
• Answer: D, E
• Answer: None