network

Introduction

This article will guide you through the process of setting up a Cisco 1801 ADSL router to a BT broadband circuit. It will probably work on other POTS ADSL suppliers as well.

Beginning the configuration

Starting with a fresh router lets begin by setting up our local inside interface. This is going to be FastEthernet0. We are going to assign this interface an address of 192.168.128.1. To do this from the routers command prompt enter the following commands:

Firstly if you are not already in configuration mode enter it by the following command:

Introduction

The Cisco 837 ADSL / Broadband router like most Cisco routers can have it's software( firmware ) upgraded. Generally this isn't a difficult process but it is a bit fiddly if you haven't done it before. This guide will walk you through this process.

Requirements

Cisco 837 router and Cisco console cable

Fairly obvious really, this is the router you wish to upgrade and the cisco serial cable used to configure the router.

Cisco 837 Firmware image

Ever had that weird problem on AIX where your routing table has a second default gateway?

I had and this is how i fixed it. In my case when I changed a ip address and default gateway in smitty, the routing table ended up with TWO default gateways. This is bad news if your machine is a seperate vLAN or subnet and needs to communicate outside of this vLAN or subnet.

The example below shows the output of a netstat -rn. In it you can see two default gateways. One is correct 10.2.98.113 and the other 10.0.72.16 is incorrect.

If you need to backup your network device's (you know Cisco, HP etc) running configuration, one of the most common ways to do this is via a TFTP server. There are various tftp solutions out there and this guide covers setting up a centos box on how to become a tftp server. There a few guides out there already but this one covers Centos 5 Linux specifically.

Step 1.
You need to install the tftp-server service and the xinetd service software using yum.
The xinetd service is required as this controls the tftp server daemon.

Using a client VPN IPSEC for remote access is a very good and is a widely used solution. However, it does require two things to work.

1. A VPN client

2. The correct IP protocol access.