Cisco Router 800 Series Software Configuration Guide

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Router Feature Configuration
This chapter includes basic feature-by-feature configuration procedures for 
Cisco 800 series and Cisco SOHO series routers. This chapter is useful if you 
have a network in place and you want to add specific features.
NoteEvery feature described is not necessarily supported on every router model. 
Where possible and applicable, feature limitations are listed.
If you prefer to use network scenarios to build a network, see Chapter 4, 
“Network Scenarios.”
This chapter contains the following sections:
Before You Configure Your Network, page 7-2
Configuring Basic Parameters, page 7-3
Configuring Bridging, page 7-14
Configuring Static Routing, page 7-17
Configuring Dynamic Routing, page 7-18
Configuring IP EIGRP, page 7-20
Configuring Addressing Parameters, page 7-22
Configuring DHCP, page 7-27
Configuring TACACS+, page 7-33
Configuring an Extended Access List, page 7-34
Configuring Quality of Service Parameters, page 7-36 
						

							 
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Before You Configure Your Network
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Configuring a Single-PVC Environment Using RFC 1483 Encapsulation, 
page 7-40
Configuring Dial Backup, page 7-53
Configuring IGMP Proxy and Sparse Mode, page 7-60
Configuring IP Security and GRE Tunneling, page 7-63
Configuring Multilink PPP Fragmentation and Interleaving, page 7-70
Configuring Voice, page 7-73
Cisco 827 Router Configuration Examples, page 7-78
Corporate or Endpoint Router Configuration for Data and Voice Network, 
page 7-83
Each section includes a configuration example and verification steps, where 
available.
Before You Configure Your Network
Before you configure your network, you must do the following:
If applicable, order an ADSL, G.SHDSL, or ISDN line from your telephone 
service provider.
Determine the number of PVCs that your service provider is giving you, 
together with their virtual path identifiers (VPIs) and virtual channel 
identifiers (VCIs).
For each PVC determine the type of AAL5 encapsulation supported. It can be 
one of the following:
–AAL5SNAP: This can be either routed RFC 1483 or bridged RFC 1483. 
In the case of routed RFC 1483, the service provider has to provide you 
with a static IP address. In the case of bridged RFC 1483, you may use 
DHCP to obtain your IP address or you may be given a static IP address 
from your service provider.
–AAL5MUX PPP: With this type, you need to determine PPP-related 
configuration items. 
						

							 
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Chapter 7      Router Feature Configuration
Configuring Basic Parameters
If you are setting up an Internet connection, gather the following information: 
–Point-to-Point Protocol (PPP) client name that is assigned as your login 
name.
–PPP authentication type: Challenge Handshake Authentication Protocol 
(CHAP) or Password Authentication Protocol (PAP).
–PPP password to access your Internet Service Provider (ISP) account.
–DNS server IP address and default gateways.
If you are setting up a connection to a corporate network, you and its network 
administrator must generate and share the following information for the 
WAN interfaces of the routers:
–PPP authentication type: CHAP or PAP.
–PPP client name to access the router.
–PPP password to access the router.
If you are setting up IP routing, generate the addressing scheme for your IP 
network.
Configuring Basic Parameters
To configure the router, perform the tasks described in the following sections:
Configuring Global Parameters
Configuring the Ethernet Interface
Configuring the Dialer Interface
Configuring the Loopback Interface
Configuring the Asynchronous Transfer Mode Interface
Configuring Command-Line Access to the Router
A configuration file example that illustrates how to configure the network is 
presented after the tasks.
After your router boots, the following prompt displays. Enter no.
Would you like to enter the initial configuration dialog [yes]: no 
						

							 
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For complete information on how to access global configuration mode, see the 
“Entering Global Configuration Mode” section on page A-8. For more 
information on the commands used in the following tables, refer to the Cisco IOS 
Release 12.0 documentation set.
Configuring Global Parameters
Follow the steps below to configure the router for global parameters.
For complete information on the global parameter commands, refer to the 
Cisco IOS Release 12.0 documentation set. 
Configuring the Ethernet Interface
Follow the steps below to configure the Ethernet interface, beginning in global 
configuration mode. Command Task
Step 1configure terminalEnter configuration mode.
Step 2hostname nameSpecify the name for the router.
Step 3enable secret passwordSpecify an encrypted password to prevent 
unauthorized access to the router.
Step 4ip subnet-zeroConfigure the router to recognize zero subnet 
range as valid range of addresses.
Step 5no ip domain-lookupDisable the router from translating unfamiliar 
words (typos) entered during a console 
session into IP addresses.
Command Task
Step 1interface ethernet 0Enter configuration mode for the Ethernet 
interface.
Step 2ip address ip-address maskSet the IP address and subnet mask for the 
Ethernet interface. 
						

							 
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For complete information on the Ethernet commands, refer to the 
Cisco IOS Release 12.0 documentation set. For more general information on 
Ethernet concepts, see Chapter 1, “Concepts.”
Configuration Example
The following example shows the Ethernet interface configuration. You do not 
need to enter the commands marked “default.” These commands appear 
automatically in the configuration file that is generated when you use the show 
running-config command.
!
interface Ethernet0
ip address 192.168.1.1 255.255.255.0
no ip directed-broadcast (default)
!
Verifying Your Configuration
To verify that you have properly configured the Ethernet interface, enter the show 
interface ethernet0 command. You should see a verification output like the 
example shown below. 
router#sh int eth0
Ethernet0 is up, line protocol is up
Hardware is PQUICC Ethernet, address is 0000.Oc13.a4db 
(bia0010.9181.1281)
Internet address is 170.1.4.101/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, 
reliability 255/255., txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Step 3no shutdownEnable the Ethernet interface to change the 
state from administratively down to up.
Step 4exitExit configuration mode for the Ethernet 
interface. Command Task 
						

							 
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Configuring the Dialer Interface 
Use these commands if you are using PPP encapsulation for the ATM PVC. 
Follow the steps below to configure the dialer interface, beginning in global 
configuration mode.
Configuration Example
The following example shows the dialer interface configuration. You do not need 
to input the commands marked “default.” These commands appear automatically 
in the configuration file that is generated when you use the show running-config 
command.
!
interface atm0
pvc 1/40
encapsulation aal5mux ppp dialer
Command Task
Step 1interface dialer number  Enter configuration mode for the dialer 
interface.
Step 2encapsulation pppSpecify the encapsulation type for the PVC as 
PPP.
Step 3ip address ip-address maskSet the IP address and subnet mask for the 
dialer interface.
Step 4dialer pool numberSpecify which dialer pool number you are 
using.
Step 5pvc vpi/vciCreate an ATM PVC for each end node with 
which the router communicates.
Step 6encapsulation aal5mux ppp dialerSpecify the encapsulation type as AAL5MUX 
PPP.
Step 7dialer pool-member numberSpecify a dialer pool-member.
Step 8dialer-group numberSpecify a dialer group. The dialer group is 
required to fast-switch outgoing packets.
Step 9exitExit configuration mode for the ATM 
interface. 
						

							 
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dialer pool-member 1
!
interface dialer 0
ip address 200.200.100.1 255.255.255.0
encapsulation ppp
dialer pool 1
!
Verifying Your Configuration
To verify that you have properly configured the dialer interface, enter the show 
interface virtual-access 1 command. Both line protocol and dialer 0 should be up 
and running. You should see a verification output like the example shown below.
router(config-if)#sh int virtual-access 1
Virtual-Access1 is up, line protocol is up 
Hardware is Virtual Access interface
Interface is unnumbered. Using address of Dialer0 (2.2.2.1)
MTU 1500 bytes, BW 100000 Kbit, DLY 100000 usec, 
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, loopback not set
Virtual-access 1 is up means that the interface is up and running. If you see the 
output Virtual-access 1 is down, it means that the interface is “administratively 
down,” and the interface is configured with the shutdown command. To bring the 
interface up, you must enter the no shutdown command.
Configuring the Loopback Interface
This section describes configuring the 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, refer to the 
Cisco IOS Release 12.0 documentation set.  
						

							 
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Configuration Tasks
Follow the steps below to configure the loopback interface.
Sample Configuration
The loopback interface in this sample configuration is used to support NAT on the 
virtual-template interface. This sample configuration shows the loopback 
interface configured on the Ethernet interface with an IP address of 
200.200.100.1/24, which acts as a static IP address. The loopback interface points 
back to virtual-template1, which has a negotiated IP address. 
!
interface Loopback0
ip address 200.200.100.1 255.255.255.0 (static IP address)
ip nat outside
!
interface Virtual-Template1
ip unnumbered loopback0
no ip directed-broadcast
ip nat outside
!
Command Task
Step 1interface Loopback 0 Enter configuration mode for the loopback 
interface.
Step 2ip address ip-address maskSet the IP address and subnet mask for the 
loopback interface.
Step 3ip  nat  outside Set the interface to be connected to the outside 
network.
Step 4exit Exit configuration mode for the loopback 
interface. 
						

							 
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Verifying Your Configuration
To verify that you have properly configured the loopback interface, enter the 
show interface loopback 0 command. You should see a verification output 
similar to the following example.
Router #sh int loopback 0
Loopback0 is up, line protocol is up 
  Hardware is Loopback
  Internet address is 200.200.100.1/24
  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 send multiple ping packets to it:
Router#ping 200.200.100.1 
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 200.200.100.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
Configuring the Asynchronous Transfer Mode Interface
Use the following steps to configure the Asynchronous Transfer Mode (ATM) 
interface, beginning in global configuration mode. 
						

							 
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NoteThe default service class for configuring the ATM interface is unspecified bit rate 
(ubr). You can change the service class to variable bit rate non-real time (vbr-nrt) 
or variable bit rate real time (vbr-rt) by using one of these commands: vbr-nrt or 
vbr-rt. Refer to the Cisco IOS Release 12.0 documentation set. For more 
information on definitions of service classes, see Chapter 1, “Concepts.” 
Command Task
Step 1interface ATM 0Enter configuration mode for the ATM 
interface.
Step 2dsl equipment-type {co | cpe} Configure the DSL equipment type, if 
applicable.
Step 3dsl linerate {number | auto} Specify the G.SHDSL line rate, if applicable. 
The range of valid numbers is between 72 and 
2312.
Step 4dsl operating-mode gshdsl symmetric 
annex annexSet the G.SHDSL operating mode, if 
applicable, and select the G.991.2 annex.
Step 5ip address ip-address maskSet the IP address and subnet mask for the 
ATM interface.
Step 6pvc vpi/vciCreate an ATM PVC for each end node with 
which the router communicates.
Step 7protocol ip ip-address broadcastSet the protocol broadcast for the IP address.
Step 8encapsulation protocolSpecify the encapsulation type for the PVC. 
Encapsulations can be specified as 
AAL5SNAP, AAL5MUX IP, or AAL5MUX 
PPP.
1
1. This step is optional. If you specify the AAL5MUX PPP encapsulation, you will need to add an additional step to specify the 
dialer pool-member number using the command dialer-pool member number.
Step 9tx-ring-limit numberConfigure the size of the PVC transmit queue. 
The default setting is 6.
Step 10no shutdownEnable the ATM interface.
Step 11exitExit configuration mode for the ATM 
interface.