Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide

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Chapter 1

Basic Router Configuration

Configuring Basic Parameters

Configuring Basic Parameters

To configure the router, perform one or more of these tasks:

•

Configure Global Parameters

•

Configure Fast Ethernet LAN Interfaces

•

Configure WAN Interfaces

•

Configuring a Loopback Interface

•

Configuring Command-Line Access to the Router

A configuration example is presented with each task to show the network configuration following

completion of that task.

Configure Global Parameters

Perform these steps to configure selected global parameters for your router:

Command

Purpose

Step 1

configure terminal

Example:

Router>

enable

Router#

configure terminal

Router(config)#

Enters global configuration mode, when using the

console port.

If you are connecting to the router using a remote

terminal, use the following:

telnet

router name or address

Login:

login id

Password: *********

Router> enable

Step 2

hostname

name

Example:

Router(config)#

hostname Router

Router(config)#

Specifies the name for the router.

Step 3

enable secret

password

Example:

Router(config)#

enable secret cr1ny5ho

Router(config)#

Specifies an encrypted password to prevent

unauthorized access to the router.

Step 4

no ip domain-lookup

Example:

Router(config)#

no ip domain-lookup

Router(config)#

Disables the router from translating unfamiliar

words (typos) into IP addresses.

For complete information on the global parameter commands, see the Cisco IOS Release 12.3

documentation set.

Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide

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Chapter 1

Basic Router Configuration

Configuring Basic Parameters

Configure Fast Ethernet LAN Interfaces

The Fast Ethernet LAN interfaces on your router are automatically configured as part of the default

VLAN and as such, they are not configured with individual addresses. Access is afforded through the

VLAN. You may assign the interfaces to other VLANs if desired. For more information about creating

VLANs, see

Chapter 5, “Configuring a LAN with DHCP and VLANs.”

Configure WAN Interfaces

The Cisco 851 and Cisco 871 routers each have one Fast Ethernet interface for WAN connection. The

Cisco 857, Cisco 877, and Cisco 878 routers each have one ATM interface for WAN connection.

Based on the router model you have, configure the WAN interface(s) using one of the following

procedures:

•

Configure the Fast Ethernet WAN Interface

•

Configure the ATM WAN Interface

Configure the Fast Ethernet WAN Interface

This procedure applies only to the Cisco 851 and Cisco 871 router models. Perform these steps to

configure the Fast Ethernet interface, beginning in global configuration mode:

Command

Purpose

Step 1

interface

type number

Example:

Router(config)#

interface fastethernet 4

Router(config-int)#

Enters the configuration mode for a Fast

Ethernet WAN interface on the router.

Step 2

ip address

ip-address mask

Example:

Router(config-int)#

ip address 192.168.12.2

255.255.255.0

Router(config-int)#

Sets the IP address and subnet mask for the

specified Fast Ethernet interface.

Step 3

no shutdown

Example:

Router(config-int)#

no shutdown

Router(config-int)#

Enables the Ethernet interface, changing its

state from administratively down to

administratively up.

Step 4

exit

Example:

Router(config-int)#

exit

Router(config)#

Exits configuration mode for the Fast Ethernet

interface and returns to global configuration

mode.

Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide

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Chapter 1

Basic Router Configuration

Configuring Basic Parameters

Configure the ATM WAN Interface

This procedure applies only to the Cisco 857, Cisco 876, Cisco 877 and Cisco 878 models.

Perform these steps to configure the ATM interface, beginning in global configuration mode:

Command

Purpose

Step 1

For the Cisco 878 model only:

controller dsl 0

mode atm

exit

Example:

Router(config)#

controller dsl 0

Router(config-controller)#

mode atm

Router(config-controller)#

exit

Router(config)#

For routers using the G.SHDSL signaling, perform

these commands. Ignore this step for routers using

ADSL signaling.

Step 2

interface

type number

Example:

Router(config)#

interface atm0

Router(config-int)#

Identifies and enters the configuration mode for an

ATM interface.

Step 3

ip address

ip-address mask

Example:

Router(config-int)#

ip address 10.10.10.100

255.255.255.0

Router(config-int)#

Sets the IP address and subnet mask for the ATM

interface.

Step 4

no shutdown

Example:

Router(config-int)#

no shutdown

Router(config-int)#

Enables the ATM 0 interface.

Step 5

exit

Example:

Router(config-int)#

exit

Router(config)#

Exits configuration mode for the ATM interface

and returns to global configuration mode.

Configure the Wireless Interface

The wireless interface enables connection to the router through a wireless LAN connection. For more

information about configuring a wireless connection, see

Chapter 9, “Configuring a Wireless LAN

Connection,”

and the

Cisco Access Router Wireless Configuration Guide

.

Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide

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Chapter 1

Basic Router Configuration

Configuring Basic Parameters

Configuring a Loopback Interface

The loopback interface acts as a placeholder for the static IP address and provides default routing

information.

For complete information on the loopback commands, see the Cisco IOS Release 12.3

documentation set.

Perform these steps to configure a loopback interface:

Command

Purpose

Step 1

interface

type number

Example:

Router(config)#

interface Loopback 0

Router(config-int)#

Enters configuration mode for the loopback

interface.

Step 2

ip address

ip-address mask

Example:

Router(config-int)#

ip address 10.108.1.1

255.255.255.0

Router(config-int)#

Sets the IP address and subnet mask for the

loopback interface.

Step 3

exit

Example:

Router(config-int)#

exit

Router(config)#

Exits configuration mode for the loopback

interface and returns to global configuration

mode.

Configuration Example

The loopback interface in this sample configuration is used to support Network Address Translation

(NAT) on the virtual-template interface. This configuration example shows the loopback interface

configured on the Fast Ethernet interface with an IP address of 10.10.10.100/24, which acts as a static

IP address. The loopback interface points back to virtual-template1, which has a negotiated IP address.

!

interface loopback 0

ip address 10.10.10.100 255.255.255.0 (

static IP address

)

ip nat outside

!

interface Virtual-Template1

ip unnumbered loopback0

no ip directed-broadcast

ip nat outside

!

Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide

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Chapter 1

Basic Router Configuration

Configuring Basic Parameters

Verifying Your Configuration

To verify that you have properly configured the loopback interface, enter the

show interface loopback

command. You should see verification output similar to the following example.

Router#

show interface loopback 0

Loopback0 is up, line protocol is up

Hardware is Loopback

Internet address is 10.10.10.100/24

MTU 1514 bytes, BW 8000000 Kbit, DLY 5000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation LOOPBACK, loopback not set

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Queueing strategy: fifo

Output queue 0/0, 0 drops; input queue 0/75, 0 drops

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

0 packets output, 0 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

Another way to verify the loopback interface is to ping it:

Router#

ping 10.10.10.100

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.10.10.100, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

Configuring Command-Line Access to the Router

Perform these steps to configure parameters to control access to the router, beginning in global

configuration mode.

Command

Purpose

Step 1

line

[

aux

|

console

|

tty

|

vty

]

line-number

Example:

Router(config)#

line console 0

Router(config)#

Enters line configuration mode, and specifies the

type of line.

This example specifies a console terminal for

access.

Step 2

password

password

Example:

Router(config)#

password 5dr4Hepw3

Router(config)#

Specifies a unique password for the console

terminal line.