Suggested prerequisite reading
»Cisco Forum FAQ »Things to expect when setup network for home or small business
Physical Connection
When it is time to configure your network router, there are basic steps you need to do regardless equipment brand or model you use. One of those steps is figuring out which would be the router WAN port and which would be router LAN port. Once you have all proper cables connected, you will then configure the router software.
In terms of plugging cables, some Cisco equipments including Cisco routers are not that clear as to which port would be WAN and which would be LAN. To find out which ports are which on your Cisco router, following preliminary hardware setup links should give you ideas. Specifically for Cisco router configuration, you need to plug in the correct cable to the router WAN, LAN, and CONSOLE port.
Cisco 800 series router
Install and Upgrade Guides
Cisco 1700 series router
Install and Upgrade Guides
Cisco 2500 series router
Cisco 2500 Series Overview
Overview of the Cisco 2500 Series Access Server
Overview of the Cisco 2517 and Cisco 2519
Cisco 2500 Multiport Installation and Configuration Guide - Router Overview
Overview of the Cisco 2524 and Cisco 2525
Cisco 2600 and 2600XM series routers
Install and Upgrade Guides
Basic Cisco Router Configuration
Next is the software setup. In software setup, you need to configure the router to have the proper IP connection scheme such as DNS, IP subnets, etc. to make WAN/LAN connection work.
There are alternatives to configure the router. Some people prefer to use Web-based feature (i.e. SDM) since it "seems" easier to use. Keep in mind that SDM is not always available on any router. Even when SDM is available, there are some features that require non-SDM to configure.
The most straight-forward way to configure the router is to use CLI (Command Line Interface). With CLI, you can configure the equipment to anything you like from basic configuration to the most advanced one.
You need to have the following items to be able to use CLI.
* Cisco console cable kit (cable and adapters)
* PC or laptop running Windows with HyperTerminal program installed (or running any operating system with terminal simulator software installed)
Do you have Cisco console kit? If no, then you could go to your local computer shop to get one. You could also buy one from ebay. Basically what you need is a RS-232 cable with DB-9 or DB-25 (depends on your computer serial port model) on one end to go to your computer serial port, and RJ-45 on another end to go to the router CONSOLE port. If your computer does not have serial port and only has USB port, then you might need a DB9-USB or DB25-USB adapter.
When you already have the CONSOLE cable and you have physical access to the CONSOLE port, then this is the 1st step you need to know.
Accessing CONSOLE port:
Connecting a Terminal or PC to the Console Port
If everything works right, you should get a prompt like this:
Router>
When you do have such display, it means you are now in CLI. The router then is ready to receive commands. You can enter the following commands as a start.
Router>enable
You may be asked to enter a password. If this is the case, you just enter the password. When the router is brand new or factory default, press ENTER on your keyboard should get you into enable/privilege mode; which shows something like this display
Router#
If by pressing ENTER you don't get into enable/privilege mode and you don't know the password, then you need to do password recovery. There's a FAQ in this forum on how to do it.
»Cisco Forum FAQ »Password Recovery Procedures
As mentioned, you should get something like this display when you pass the password question,
Router#
where the prompt changes from > to #.
This means you are in enable/privilege mode. When you are in privilege mode, you can check the router configuration. To do so, issue following command:
Router#show running-config
Keep in mind that the output you are about to see might not exactly match to the following. The output basically varies; it highly depends on your router models and features activated or used. However in general, it should look something like this.
!
version 12.2
no service single-slot-reload-enable
no service pad
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname Router
!
!
ip subnet-zero
!
!
!
!
!
!
interface Ethernet0
no ip address
shutdown
!
interface Ethernet1
no ip address
shutdown
!
ip classless
no ip http server
no cdp run
!
line con 0
exec-timeout 120 0
stopbits 1
line vty 0 4
exec-timeout 0 0
login local
length 0
!
scheduler max-task-time 5000
end
As mentioned, you need to configure the router to have the proper IP connection scheme such as DNS, IP subnets, etc. In order to do that, you have to enter the global configuration mode by issuing the following command
Router#configure terminal
Then you should have the following display.
Router(config)#
That prompt indicates that you are in the configuration mode.
As illustration, let us say that the interface Ethernet1 is the WAN port and interface Ethernet0 is the LAN port. Then you should enter the WAN IP subnets under the interface Ethernet1 and the LAN IP subnets under the interface Ethernet0.
Let us say that the following is the IP subnets:
WAN:
Subnet: 23.42.53.0/24 network (or 23.42.53.0 network with subnet mask of 255.255.255.0)
IP address: 23.42.53.24
Default Gateway: 23.42.53.1
DNS: 23.42.52.1
LAN:
Subnet: 10.10.10.0/24 network (or 10.10.10.0 network with subnet mask of 255.255.255.0)
IP address: 10.10.10.1
To configure these info, the general idea is to do the following:
1. To make sure the router is working as expected, there might be a need to set several things such as set the router to do ip routing and to keep the manufacturer's suggested settings
2. Enter the interface configuration mode
3. Type in the interface IP address and subnet mask
4. Issue "no shutdown" command to bring up the interface
5. Exit the interface configuration mode to global configuration mode
6. On the global configuration mode, enter the default gateway.
7. Save the configuration.
Here are the walkthrough configuration steps.
Since you plan to configure a router and expect it to do IP routing, then following command is to make sure that the router will be in routing mode.
Router(config)#ip routing
This command is to make sure that the router will keep all settings as advised by the manufacturer (which is Cisco of course).
Router(config)#config-register 0x2102
Side Note:
Check out this FAQ for more info on the default config register value
»Cisco Forum FAQ »Config Register Value - After lost power or reload, router lost configuration
The WAN interface:
Router(config)#interface Ethernet1
Router(config-if)#description Outside World
Router(config-if)#ip address 23.42.53.24 255.255.255.0
Router(config-if)#no shutdown
Router(config-if)#exit
Router(config)#
The LAN interface:
Router(config)#interface Ethernet0
Router(config-if)#description Internal LAN
Router(config-if)#ip address 10.10.10.1 255.255.255.0
Router(config-if)#no shutdown
Router(config-if)#exit
Router(config)#
To configure the default gateway, do the following:
Router(config)#ip route 0.0.0.0 0.0.0.0 23.42.53.1
Keep in mind that in this illustration, it is assumed that you have WAN static IP address scheme in Ethernet environment. When this does not match your situation, please go to the FAQ subsection and find the most suitable environment (PPP, DHCP, etc.).
There should be no further necessary step of configuring the router. You then need to exit the configuration mode and save the changes, by doing the following.
Router(config)#end
Router#copy running-config startup-config
As to the DNS info, you need to inject it into your LAN machines. You can do it either statically or automatically. When you do it statically, it usually means that you configure the LAN machines to have static IP address. When you do it automatically, it usually means that you configure the LAN machines to have dynamic IP address.
Keep in mind that LAN machine configuration step varies, it highly depends on the operating system (i.e. Windows, Mac, or Linux). In general is that when you configure the LAN machines to have either static or dynamic IP address, go to the machine configuration mode and do it from there.
Note:
This FAQ is written with purpose of introducing CLI to novices. Therefore this FAQ is not intended as the complete guideline on how to setup a router in specific WAN/LAN environment or setup a used router with saved configuration file already in place. When the router is going to connect directly to an ISP via cable modem, DSL, or T1/E1; please go to other FAQ subsections and find the most suitable environment (PPP, DHCP, static, etc.). If you are not sure how the router should connect to the ISP, please consult with the ISP since your ISP is the most knowledgeable source concerning their own connection to the customers.
Following is the FAQ of router configuration in specific WAN/LAN environment
Various PPPoE/PPPoA/DHCP/Static Sample Configuration with Cisco
For further info on command descriptions, check out the following
»Cisco Forum FAQ »Basic Cisco Commands and Descriptions
»Cisco Forum FAQ »Basic Configuration of Cisco devices
Guide to ISP consultation in finding out how to connect to the ISP
»Cisco Forum FAQ »Between DHCP, PPP, Dynamic, and Static IP Address
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by aryoba 
last modified: 2009-03-30 09:16:58 |
