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Cisco1800 Series Integrated Services Routers (Fixed) Software Configuration Guide
OL-6426-02
Chapter1 Basic Router Configuration
Configuring Basic Parameters
Configure WAN Interfaces
The Cisco 1811 and Cisco 1812 routers each have two Fast Ethernet interfaces for WAN connection. The
Cisco 1801, Cisco 1802, and Cisco1803 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 1811 and Cisco 1812 router models. Perform these steps to
configure the Fast Ethernet interfaces, beginning in global configuration mode.
Repeat these steps for the other Fast Ethernet WAN interface if desired.
Note Due to a limitation on the internal transceiver of the on-board layer-3 Fast Ethernet interfaces available
on Cisco 1812 Ethernet Access Routers, configuring the interface with a speed of 10 Mbps may cause
some CRC errors to appear on the interface. This is an expected behavior of the Cisco 1812 routers
on-board layer-3 Fast Ethernet interface.
Command Purpose
Step1 interface type number
Example:
Router(config)#interface fastethernet 0
Router(config-int)#
Enters the configuration mode for a Fast
Ethernet WAN interface on the router.
Note Fast Ethernet WAN ports are numbered
0–1 on the Cisco1800 series routers.
Step2 ip address ip-address mask
Example:
Router(config-int)# ip address 192.1.12.2
255.255.255.0
Router(config-int)#
Sets the IP address and subnet mask for the
specified Fast Ethernet interface.
Step3 no shutdown
Example:
Router(config-int)# no shutdown
Router(config-int)#
Enables the Ethernet interface, changing its
state from administratively down to
administratively up.
Step4 exit
Example:
Router(config-int)# exit
Router(config)#
Exits interface configuration mode and returns
to global configuration mode.