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»Cisco Forum FAQ »Things to expect when setup network for home or small business

Physical Connection

Part of basic steps in configuring network router regardless of equipment brand or model is to identify which would be the router WAN port and which would be router LAN port. Another part is locate proper cables to connect to. Once you have all cables connected, you will then configure the router software.

In terms of plugging cables, some Cisco equipment including Cisco routers are not descriptive as to which port would be WAN and which would be LAN. To find out, following 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 ports.

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, some features may require non-SDM to configure.

A 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 visit any 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.



Note:

It is preferable to use either DB-9 or DB-25 serial port for console in instead of using USB port. In some cases, using DB9-USB or DB25-USB adapter may not work; depending on the adapter model itself or adapter setting.




When you already have the CONSOLE cable and you have physical access to the CONSOLE port, then following is illustration.

Accessing CONSOLE port:
Connecting a Terminal or PC to the Console Port



Note:

This FAQ assumes that the router CONSOLE port baud speed and setting is default. This default setting means that you can actually see a display coming out of the CONSOLE port. If the display is unreadable or stop being readable, the router CONSOLE port setting may have been altered. Check out the following FAQ to set the setting back to default.

»Cisco Forum FAQ »Unreadable output from Cisco Router/Switch Console port




Discussions
»[HELP] Some 1841 questions

If everything works right, you should get a prompt like this:

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.

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.



Note:

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 - proper BREAK key sending



Notice the prompt change when you pass the password question

from > to #.

When you see the # prompt, this means you are in enable/privilege mode. Being in privilege mode, you can check the router configuration. To do so, issue following command:

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.



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.

Then you should have the following display.

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.

For the sake of discussion, assume following the IP subnet info.

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.

This command is to make sure that the router will keep all settings as advised by the manufacturer (which is Cisco of course).

Side Note:

Check out this FAQ for more info on the default config register value
Config Register Value - router lost configuration, how to recover

The WAN interface


The LAN interface

To configure the default gateway, do the following.

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.

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. This FAQ is not intended as a complete guideline on how to setup a router to connect to the Internet in specific WAN/LAN environment or setup a used router with saved configuration file already in place. If you are trying to connect the router with the rest of your network or trying to connect the router to any network devices, please carefully review how you like the network looks like and how each network device (such as modem, routers, switches, and firewalls) interacts and inter-communicates.

When the router is going to connect to the Internet provided by 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. You can check out the following FAQ to get better ideas of how to review and discuss technical requirement with ISP support.
Things to expect when setup network for home or small business

Some FAQ links of router configuration in specific WAN/LAN environment
Various PPPoE/PPPoA/DHCP/Static Sample Configuration with Cisco
Router-Firewall Combo
Various Sample Network Design with Routers, Switches, and Firewalls

For Cisco IOS command further descriptions, check out the following
Basic Cisco IOS Commands and Descriptions
Basic Configuration of Cisco devices

Guide to ISP consultation in finding out how to connect to the ISP
Between DHCP, PPP, Dynamic, and Static IP Address

Still confused?

When you find yourself still confused after reviewing all above links and descriptions, post a question by creating a new thread on Cisco forum in following this guide.
How do I post in the forum?


Feedback received on this FAQ entry:
  • superb explanation

    2013-01-11 09:41:29



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last modified: 2015-10-30 10:19:24