Cisco Router 850 Series Software Configuration Guide

							
 
1-11
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01 
Chapter 1      Basi c Router Configuration
  Configuring Static Routes
Configuration Example
The following configuration shows the command-line access commands.
You do not need to input the commands marked “default.” These commands appear automatically in the 
configuration file generated when you use the show running-config command.
!line con 0
exec-timeout 10 0
password 4youreyesonlylogin
transport input none  (default)
stopbits 1 (default)line vty 0 4
password secret
login!
Configuring Static Routes
Static routes provide fixed routing paths through the network. They are manually configured on the 
router. If the network topology changes, the static route must be updated with a new route. Static routes 
are private routes unless they are redistributed by a routing protocol. Configuring static routes on the 
Cisco
 850 and Cisco 870 series routers is optional.
Perform these steps to configure static routes, beginning in global configuration mode:
CommandPurpose
Step 1ip route prefix mask  {ip-address  | interface-type  
interface-number  [ip-address ]} 
Example:
Router(config)#  ip route 192.168.1.0 
255.255.0.0 10.10.10.2
Router(config)# 
Specifies the static route for the IP packets.
For details about this command and additional 
parameters that can be set, see the 
Cisco IOS IP 
Command Reference, Volume 2 of 4: Routing 
Protocols.
Step 2end
Example:
Router(config)#  end
Router# 
Exits router configuration mode, and enters 
privileged EXEC mode.
For complete information on the static routing commands, see the Cisco IOS Release 12.3 
documentation set. For more general information on static routing, see 
Appendix B, “Concepts.” 
						

							 
1-12
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01 
Chapter 1      Basic Router Configuration
  Configuring Dynamic Routes
Configuration Example
In the following configuration example, the static route sends out all IP packets with a destination IP 
address of 192.168.1.0 and a subnet mask of 255.255.255.0 on the Fast Ethernet interface to another 
device with an IP address of 10.10.10.2. Specifically, the packets are sent to the configured PVC.
You do not need to enter the commands marked “(default).” These commands appear automatically in 
the configuration file generated when you use the show running-config command.
!ip classless (default)
ip route 192.168.1.0 255.255.255.0 10.10.10.2!
Verifying Your Configuration
To verify that you have properly configured static routing, enter the show ip route command and look 
for static routes signified by the “S.” 
You should see verification output similar to the following example.
Router# show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
     10.0.0.0/24 is subnetted, 1 subnetsC       10.108.1.0 is directly connected, Loopback0
S* 0.0.0.0/0 is directly connected, FastEthernet0
Configuring Dynamic Routes
In dynamic routing, the network protocol adjusts the path automatically, based on network traffic or 
topology. Changes in dynamic routes are shared with other routers in the network.
The Cisco routers can use IP routing protocols, such as Routing Information Protocol (RIP) or Enhanced 
Interior Gateway Routing Protocol (EIGRP), to learn routes dynamically. You can configure either of 
these routing protocols on your router. 
						

							
 
1-13
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01 
Chapter 1      Basi c Router Configuration
  Configuring Dynamic Routes
Configuring RIP
Perform these steps to configure the RIP routing protocol on the router, beginning in global 
configuration mode:
CommandTa s k
Step 1router rip
Example:
Router> configure terminal
Router(config)#  router rip
Router(config-router)# 
Enters router configuration mode, and enables RIP 
on the router.
Step 2version {1 |  2}
Example:
Router(config-router)#  version 2
Router(config-router)# 
Specifies use of RIP version 1 or 2.
Step 3network ip-address
Example:
Router(config-router)#  network 192.168.1.1
Router(config-router)# network 10.10.7.1Router(config-router)# 
Specifies a list of networks on which RIP is to be 
applied, using the address of the network of 
directly connected networks.
Step 4no auto-summary
Example:
Router(config-router)# no auto-summary
Router(config-router)# 
Disables automatic summarization of subnet routes 
into network-level routes. This allows subprefix 
routing information to pass across classful network 
boundaries.
Step 5end
Example:
Router(config-router)# end
Router# 
Exits router configuration mode, and enters 
privileged EXEC mode.
For complete information on the dynamic routing commands, see the Cisco IOS Release 12.3 
documentation set. For more general information on RIP, see 
Appendix B, “Concepts.”  
						

							 
1-14
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01 
Chapter 1      Basic Router Configuration
  Configuring Enhanced IGRP
Configuration Example
The following configuration example shows RIP version 2 enabled in IP network 10.0.0.0 and 
192.168.1.0.
Execute the show running-config command from privileged EXEC mode to see this configuration.
!router rip
 version 2
 network 10.0.0.0 network 192.168.1.0
 no auto-summary
!
Verifying Your Configuration
To verify that you have properly configured RIP, enter the show ip route command and look for RIP 
routes signified by “R.” You should see a verification output like the example shown below. 
Router# show ip routeCodes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
     10.0.0.0/24 is subnetted, 1 subnets
C       10.108.1.0 is directly connected, Loopback0
R    3.0.0.0/8 [120/1] via 2.2.2.1, 00:00:02, Ethernet0/0
Configuring Enhanced IGRP
Perform these steps to configure Enhanced IGRP (EIGRP), beginning in global configuration mode:
CommandPurpose
Step 1router eigrp as-number
Example:
Router(config)# router eigrp 109Router(config)# 
Enters router configuration mode, and enables 
EIGRP on the router. The autonomous-system 
number identifies the route to other EIGRP routers 
and is used to tag the EIGRP information. 
						

							 
1-15
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01 
Chapter 1      Basic Router Configuration
  Configuring Enhanced IGRP
For complete information on the IP EIGRP commands, see the Cisco IOS Release 12.3 documentation 
set. For more general information on EIGRP concepts, see 
Appendix B, “Concepts.”
Configuration Example
The following configuration example shows the EIGRP routing protocol enabled in IP networks 
192.145.1.0 and 10.10.12.115. The EIGRP autonomous system number is 109.
Execute the show running-config command from privileged EXEC mode to see this configuration.
!router eigrp 109
network 192.145.1.0
network 10.10.12.115!
Verifying Your Configuration
To verify that you have properly configured IP EIGRP, enter the show ip route command, and look for 
EIGRP routes indicated by “D.” You should see verification output similar to the following example.
Router# show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
     10.0.0.0/24 is subnetted, 1 subnets
C       10.108.1.0 is directly connected, Loopback0
D    3.0.0.0/8 [90/409600] via 2.2.2.1, 00:00:02, Ethernet0/0
Step 2network ip-address
Example:
Router(config)# network 192.145.1.0Router(config)# network 10.10.12.115
Router(config)# 
Specifies a list of networks on which EIGRP is to 
be applied, using the IP address of the network of 
directly connected networks.
Step 3end
Example:
Router(config-router)# endRouter# 
Exits router configuration mode, and enters 
privileged EXEC mode.
Command Purpose 
						

							 
1-16
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01 
Chapter 1      Basic Router Configuration
  Configuring Enhanced IGRP 
						

							 
PART 2
Configuring Your Router for Ethernet and 
DSL Access 
						

							CH A P T E R
 
2-1
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01 
2
Sample Network Deployments
This part of the software configuration guide presents a variety of possible Ethernet- and Digital 
Subscriber Line (DSL)-based network configurations using the Cisco
 850 and Cisco 870 series access 
routers. Each scenario is described with a network topology, a step-by-step procedure that is used to 
implement the network configuration, and a configuration example that shows the results of the 
configuration. The Cisco
 851 and Cisco 871 router models can be used in the Ethernet-based scenarios 
and the Cisco
 857, Cisco 876, Cisco 877, and Cisco 878 router models can be used in the DSL-based 
scenarios.
The first network scenario provides a simple network configuration: point-to-point protocol (PPP) over 
the WAN interface with Network Address Translation (NAT). Each successive scenario builds on the 
previous scenario by configuring another key feature.
The scenarios do not address all of the possible network needs; instead, they provide models on which 
you can pattern your network. You can choose not to use features presented in the examples, or you can 
add or substitute features that better suit your needs. 
NoteTo verify that a specific feature is compatible with your router, you can use the Software Advisor tool. 
You can access this tool at www.cisco.com > Technical Support & Documentation > Tools & 
Resources with your Cisco username and password.
For Ethernet-Based Network Deployments
Use the following configuration examples to assist you in configuring your router for Ethernet-based 
networks.
 Chapter 3, “Configuring PPP over Ethernet with NAT”
 Chapter 5, “Configuring a LAN with DHCP and VLANs”
 Chapter 6, “Configuring a VPN Using Easy VPN and an IPSec Tunnel”
 Chapter 7, “Configuring VPNs Using an IPSec Tunnel and Generic Routing Encapsulation”
 Chapter 8, “Configuring a Simple Firewall”
For DSL-Based Network Deployments
Use the following configuration examples to assist you in configuring your router for DSL-based 
networks.
 Chapter 4, “Configuring PPP over ATM with NAT”
 Chapter 5, “Configuring a LAN with DHCP and VLANs”
 Chapter 6, “Configuring a VPN Using Easy VPN and an IPSec Tunnel” 
						

							 
2-2
Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
OL-5332-01 
Chapter 2      Sample Network Deployments
  
 Chapter 7, “Configuring VPNs Using an IPSec Tunnel and Generic Routing Encapsulation”
 Chapter 8, “Configuring a Simple Firewall”