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It’s been a couple of years since I’ve done anything with this router, but I’ll be trying some things out with a managed switch I’ve acquired. A some point I’ll get an Adtran for linking both routers also.
On the hardware I’m using there are Ethernet, Console and Aux interfaces on the router itself, and four BRI interfaces on the module. The Ethernet interface (with the yellow cable) is for the LAN, and the BRI interface (blue cable) links the router to another router or exchange.

Cisco-BRI-and-Eth-Interfaces

To configure the router, you’ll need 1) a terminal emulator, 2) console cable, and most likely 3) a serial-to-USB adapter. I use the same connectors and terminal emulator for managing an HP Procurve switch.

Terminal Emulator Settings
Here I’ve used minicom as my terminal emulator. When running it the first time, there’ll be a configuration menu. Select the ‘Serial Port Setup‘ option, and change the configuration to the following:

minicom-settings

Then back in the main minicom menu, ‘Save setup as dfl‘.

If minicom is already running before the router is switched on, something like the following boot message should appear:

cisco-2600-boot-2

And depending on whether a startup configuration file was detected, there might be the option to run through the initial configuration dialogue.

Prepping the Interfaces
The first thing you’d want to know is which interfaces are present with the following command:
Router>show ip interface brief

By default, none of the interfaces have an internal or external IP address, and none are active:

cisco-interfaces-non-configured

For that, we must enable admin mode using the ‘enable’ command. The prompt will change to ‘Router#‘.

If we use the following comand, I can see that all interfaces are present but none are initialised for routing:
Router#show running-config

interface Ethernet0/0
no ip address
shutdown
half-duplex

So the next step is to enter the configuration mode with the ‘configure terminal‘ command, and the prompt will change to:
Router(config)#

Before changing anything, let’s think about the address range we want for the LAN, and the subnetting. Obviously it’s going to be an RCF 1918 address range, and since I don’t expect to have that many hosts on the network, 255.255.255.0 seems a good subnet mask. If I remember correctly, routing only happens if/when the 255 addresses are exhausted and we end up assigning addresses outside that range.

So, I want the internal Ethernet interface to have an IP address of 10.0.0.1, just to differentiate it from my other home network.

Enter the configuration for the Ethernet0 interface and set its IP address, netmask, state and description (optional):
Router(config)#interface Ethernet0/0
Router(config-if)#ip address 10.0.0.1 255.255.255.0
Router(config-if)#no shutdown
Router(config-if)#description LAN gateway interface

Then ‘exit‘ and ‘end‘.

The external interfaces (BRI/PRI) won’t be doing much for a while, but it would be nice to give one of them an IP address also. For the purpose of this, I just set it to have a static address of 192.168.200.1.

If we run the ‘show ip interface brief‘ command again, we see that both interfaces are up, and both have an IP address.

cisco-show-configured-interfaces

If we’re happy with the setup so far, the current running configuration can be written to file as the startup configuration with:
Router#copy running-config startup-config

cisco-save-running-config

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