Asymmetric Digital Subscriber Line (ADSL)

Cisco DSL Router Configuration and Troubleshooting Guide - Step-by-Step Configuration of RFC1483 Pure Bridging

Document ID: 71128

Updated: Sep 26, 2006



Your Internet Service Provider (ISP) has assigned an RFC1483 Bridging connection.



There are no specific requirements for this document.

Components Used

This document is not restricted to specific software and hardware versions.


Refer to Cisco Technical Tips Conventions for more information on document conventions.


Important: Before you begin, close all programs on the PC that might be monitoring your COM port. Devices such as PDAs and digital cameras often place programs in the system tray that will render your COM port unusable for configuring your Cisco Digital Subscriber Line (DSL) Router.

Connect the Cisco DSL Router and Your PC

A console connection is made with a rolled cable and connects the console port of the Cisco Digital Subscriber Line (DSL) Router to a COM port on a PC. The console cable that is included with the Cisco DSL Router is a flat light blue cable. For more information on the pinouts of a rolled cable, or the pinouts of an RJ-45 to DB9 converter, refer to Cabling Guide for Console and AUX Ports.

  1. Connect the RJ-45 connector on one end of a Cisco console cable to the console port of the Cisco DSL Router.

  2. Connect the RJ-45 connector at the other end of the console cable to an RJ-45 to DB9 converter.

  3. Connect the DB9 connector to an open COM port on your PC.

Start and Set Up HyperTerminal

Complete these steps:

  1. Start the HyperTerminal program on the PC.

  2. Set up your HyperTerminal session.

    1. Assign a name to your session, and click OK.

    2. From the Connect To window, click Cancel.

    3. From the File menu, click Properties.

    4. From the Properties window, in the Connect Using list, select the COM port where you connect the DB9 end of the console cable.

    5. From the Properties window click Configure and fill in these values:

      • Bits per second: 9600

      • Data bits: 8

      • Parity: None

      • Stop bits: 1

      • Flow Control: None

    6. Click OK.

    7. From the Call menu, click Disconnect.

    8. From the Call menu, click Call.

    9. Press Enter until you see a router prompt on your HyperTerminal screen.

Clear Existing Configurations on the Cisco DSL Router

Complete these steps:

  1. Type enable at the router prompt to enter privileged mode.

    !--- The # symbol indicates that you are in privileged mode.
  2. Clear existing configurations on the router.

    Router#write erase
  3. Reload the router so it boots with a blank startup configuration.

    System configuration has been modified. Save? [yes/no]:no
    Proceed with reload? [confirm]yes
    !--- Reloading the router can take a few minutes.
  4. After the router has reloaded, enter enable mode again.


Configure the Cisco DSL Router

Complete these steps:

  1. Configure service timestamp to properly log and display debug output in the troubleshooting section.

    Router#configure terminal
    Router(config)#service timestamps debug datetime msec
    Router(config)#service timestamps log datetime msec
  2. Disable the logging console on your Cisco DSL Router to suppress console messages that may be triggered while you are configuring the router.

    Router#configure terminal
    Router(config)#no logging console
  3. Configure a bridge protocol and disable routing on your Cisco DSL Router.

    Router#configure terminal
    Router(config)#no ip routing
    Router(config)#bridge 1 protocol ieee
  4. Configure a bridge group on the Cisco DSL Router Ethernet interface.

    Router#configure terminal
    Router(config)#interface ethernet 0
    Router(config-if)#bridge group 1
    Router(config-if)#no shut
  5. Configure the ATM interface of your Cisco DSL Router with an ATM permanent virtual circuit (PVC), encapsulation type, and bridge group.

    Router#configure terminal
    Router(config)#interface atm 0
    Router(config-if)#bridge-group 1
    Router(config-if)#pvc <vpi/vci>
    Router(config-if-atm-vc)#encapsulation aal5snap
    Router(config-if-atm-vc)#no shut
  6. Enable the logging console on the Cisco DSL Router, and write all the changes to memory.

    Router#configure terminal
    Router(config)#logging console
    *Jan 1 00:00:00.100: %SYS-5-CONFIG_I: Configured from console by console
    Router#write memory
    Building configuration... [OK]


This is the configuration that results after you complete the procedures in this document.

Cisco DSL Router with RFC1483 Pure Bridging

!--- Comments contain explanations and additional information.

service timestamps debug datetime msec
service timestamps log datetime msec
no ip routing
interface ethernet0
 no shut
 no ip directed-broadcast
 bridge-group 1
interface atm0
 no shut
 no ip address
 no ip directed-broadcast
 no atm ilmi-keepalive
 pvc <vpi/vci>
  encapsulation aal5snap
!--- Common PVC values supported by ISPs are 0/35 or 8/35.
 !--- Confirm your PVC values with your ISP.

 bridge-group 1
bridge 1 protocol ieee


Your Cisco DSL Router should now be operational for Asymetric Digital Subscriber Line (ADSL) service. You can issue a show run command in order to see the configuration.

Router#show run
Building configuration...

The Output Interpreter Tool (registered customers only) (OIT) supports certain show commands. Use the OIT to view an analysis of show command output.


If your ADSL service does not work properly, refer to RFC1483 Pure Bridging Troubleshooting.

Related Information

Updated: Sep 26, 2006
Document ID: 71128