.
.

The basic configuration of Cisco Router

I read on the more forums questions beginners who asked the question, What is the router? What is the purpose etc etc..
Many unlearned people think that the router device having at home to be connected and constantly reminds them at home device.
There are several types of devices that can be called router so the routing function can serve one desktop computer (PC) with certain Operating systems (eg. PCs with OS Win2k or 2003, 2008).

This unit of special-purpose router is a computer with all the internal components of the primary and its operating system, for example. IOS (for Cisco routers)

This tutorial that I made ??in my understanding router and its functions are learned from the Cisco Networking Academy CCNA on the course.

To which serves router?
In layman's terms, the router connects multiple networks that redirects traffic from one network to another.

The router simply by using certain protocols (some known as RIP, IGRP, OSPF, IS-IS, etc..) Calculates the path to the destination. So you are surfing the Internet, packets sent from your computer exceed through multiple router to reach the destination and return back to your computer.

It all happens very quickly in milli-seconds (microseconds?). When you in the Web browser, you type a web address for a short time you appear concerned website and you may not even aware that after ENTER request your computer went through dozens Router outgoing and returning by way of changing the IP address.

How Looks router?
Pets device through which you connect to the Internet via an ADSL line or whatever also has a Router but that's not the device that we mean when we say the router on Internet traffic and network.
One of the most popular commercial device manufacturers Router for Internet use is Cisco (wwwcisco.com). In this tutorial I'll stick to the CISCO router.

Here's a picture to look Router series Cisco.

Figure 1.

Back view of the Cisco router and ports

Back view of Cisco routers and connections serie 1720

As you can see in the picture above are devices that has a ports (ports/interfaces).

Figure1a. demonstrates the use of the router on the Internet network. Recent present a major network. For example: Internet and Computers, A, B, C network, while the upper computer is administrative unit with which we can through some applications (eg Hyper Terminal) reconfiguration router.

Figure 1a.

How to connect multiple networks through two routers

As I said in the router itself has circuitry similar to those in a computer (PC).
Figure2 you may see some basic internal electronic components of the router, and Figure 3 and 4 of the terminal connections at the rear of the router.

Figure 2.

View of the electronic components of the router
Figure 3.

Ports on the router to connect to the network
Figure 4

Example of a Cisco router from the rear and ports

The router in its electronic hardware contains some basic groups that are important for the operation and functioning of the router. Figuratively it can be displayed as in Figure 5.

Figure 5.

Cisco router and its operating parts
Basic Router features are:
- RAM is used for routing information from the table, quickly switchanje cache, driving configuration and "placing the package in the order on hold."
- NVRAM is used to store backup / startup configuration file.
- FLASH memory is used to store the entire Cisco IOS software image. (Operating system)
- ROM is used to store (permanently) diagnostic startup code, at system startup when you turn on the router ..
- CONSOLE port provides physical access for connecting the PC and the administration Router.
- INTERFACES - Connection ports that allow LAN and WAN connections.

PC connection for administering the Router

Computer (PC) is connected to the router via the console port using the so-called: Rollover cable that connects via adapter RJ45/DB9. UTP RJ-45 connector is connected to the DB-9 adapter and the adapter to the COM port on the computer.

How does it look Rollover cable? The pins are connected inversely 1-8 and 8-1.

Figure 6.

Graphic scheme of connecting wires Rollover Cable

Figure 6a.

How to connect a rollover cable to the router via an adapter DB9

Also, the rollover cable is for connecting the AUX port and a modem via an RJ-45/DB25 adapter.
After a successful connection to the router, using eg Hyper Terminal after setting the same can access the Comand Line Interface (CLI prompt) on the router.
The word "interface", do not be understood as the power port (such as, serial, ethernet ports, etc. interfaces). Here the word "interface" means that interface. Command line where we write commands. (Something like a DOS prompt)

Before we access the CLI prompt to the router you need to set some parameters for the connection to the COM port of the computer. See Figure7.

Figure 7.

The dialog box for the Administration of Cisco routers

After accessing the Comand line interface appears to us to part of code, which shows that the router has successfully started and prompt which is a starting position on the router.
There are two basic modes Router in which we can work
  - User mode
  - Privileged mode

User mode prompt looks like this: Router> in it, you can view some router settings

Privileged mode prompt looks like this: Router #  it can re-configure the router

You're probably asking a question, What are the commands you can key in a certain mode?
For knowledge about them is enough to type the question mark '?' and will list you all the commands in that moment you typed. Sure to get you to work on the configuration of the router you have to know the commands and what they execute. To access the Privileged mode you must know the password (if set).

Basic configuration of the router

In order be functional router minimum necessary to set certain parameters on it. Some of them, password, IP address interface (port), the encryption password, the name of the Router etc etc..

I will describe only some basic parameters as well as the order of the configuration on the router and I hope that I, well able to explain the following actions.

Therefore, the router needs to be configured as follows:

- The name of the router
- The welcome note or warning or something (when connecting to the router)
- Password for access via the console port (rollover cable)
- Password for access via Telnet lines (access from a remote router)
- IP addresses for each interface (port for connection) (Serial, Ethernet or Fast Ethernet) + Subnet Mask
- Description of each Interface
- Message after the access router (Banners - login or message-of-the-day)
- Host table ie. The name of the neighboring router and its IP address (Host Tables - which is important because of the accession through a Telnet connection)
  - Activating the password on the router
  - Encryption for Password

To be able to configure the router must enter the "Privileged Mode" in the "Global Configuration Mode" (#configure terminal)
There are specific sub-modes for specific parameters to configure

Figure 8.

User exec mode, Privileged exec mode i Global configuration mode on the Cisco Router

Using a simulator for router specifically 1841. I'll try to show you how to configure the router with a basic configuration (Basic Router Configuring)

During a boot (startup Router) appears code that asks you to confirm the Y or N
The example code below is for the Router 1841 (simulation)


System Bootstrap, Version 12.3(8r)T8, RELEASE SOFTWARE (fc1)
 Cisco 1841 (revision 5.0) with 114688K/16384K bytes of memory.

 Self decompressing the image :
 ########################################################################## [OK]
               Restricted Rights Legend

 Use, duplication, or disclosure by the Government is
 subject to restrictions as set forth in subparagraph
 (c) of the Commercial Computer Software - Restricted
 Rights clause at FAR sec. 52.227-19 and subparagraph
 (c) (1) (ii) of the Rights in Technical Data and Computer
 Software clause at DFARS sec. 252.227-7013.

            cisco Systems, Inc.
            170 West Tasman Drive
            San Jose, California 95134-1706

 Cisco IOS Software, 1841 Software (C1841-IPBASE-M), Version 12.3(14)T7, RELEASE SOFTWARE (fc2)
 Technical Support: http://www.cisco.com/techsupport
 Copyright (c) 1986-2006 by Cisco Systems, Inc.
 Compiled Mon 15-May-06 14:54 by pt_team
 Image text-base: 0x6007D180, data-base: 0x61400000

 Port Statistics for unclassified packets is not turned on.
 Cisco 1841 (revision 5.0) with 114688K/16384K bytes of memory.
 Processor board ID FTX0947Z18E
 M860 processor: part number 0, mask 49
 2 FastEthernet/IEEE 802.3 interface(s)
 191K bytes of NVRAM.
 31360K bytes of ATA CompactFlash (Read/Write)
 Cisco IOS Software, 1841 Software (C1841-IPBASE-M), Version 12.3(14)T7, RELEASE SOFTWARE (fc2)
 Technical Support: http://www.cisco.com/techsupport
 Copyright (c) 1986-2006 by Cisco Systems, Inc.
 Compiled Mon 15-May-06 14:54 by pt_team

          --- System Configuration Dialog ---

Continue with configuration dialog? [yes/no]: N  // potvrdite sa slovom "N"
 Press RETURN to get started!
 Router>

After pressing Enter will appear "comand prompt" USER EXEC mode in which you can type "?" Descendants and you list all the commands that can be executed in this mode, see the code below.

Router>?
 access-enable ……….. Create a temporary Access-List entry
 access-profile ……….. Apply user-profile to interface
 connect ……….. Open a terminal connection
 disable ……….. Turn off privileged commands
 disconnect ……….. Disconnect an existing network connection
 enable ………..  Turn on privileged commands
 exit ……….. Exit from the EXEC
 help ……….. Description of the interactive help system
 lock ……….. Lock the terminal
 login ……….. Log in as a particular user
 logout ……….. Exit from the EXEC
 mrinfo ……….. Request neighbor and version information from a multicast router
 mstat ……….. Show statistics after multiple multicast traceroutes
 mtrace ……….. Trace reverse multicast path from destination to source
 name-connection ……….. Name and existing network connection
 pad ……….. Open a X.29 PAD connection
 ping ……….. Send echo messages
 ppp ……….. Start IETF Point-to-Point Protocol (PPP)
 resume ……….. Resume an active network connection
 rlogin ……….. Open an rlogin connection
 Show ……….. Show running system information
 slip ……….. Start a Serial-line IP (SLIP)
 systat ……….. Display information about terminal lines
 telnet ……….. Open a telnet connection
 terminal ……….. Set terminal line parameters
 traceroute ……….. Trace route to destination
 tunnel ……….. Open a tunnel connection
 udptn ……….. Open an updtn connection
 x28 ……….. Become an X.28 PAD
 x3 ……….. Set X.3 parameters on PAD

In contrast, when the same question mark "?" you enter the Privileged mode

Router#?
 access-template   …………   Create a temporary Access-List entry
 alps   …………   ALPS exec commands
 archive   …………   manage archive files
 bfe   …………   For manual emergency modes setting
 cd   …………   Change current directory
 clear   …………   Reset functions
 clock   …………   Manage the system clock
 configure   …………   Enter configuration mode
 copy   …………   Copy from one file to another
 debug   …………   Debugging functions (see also 'undebug')
 delete   …………   Delete a file
 dir   …………   List files on a filesystem
 disable                    …………
disconnect   …………   Disconnect an existing network connection
 elog   …………   Event-logging control commands
 erase   …………   Erase a filesystem
 exit                       …………
logout   …………   Exit from the EXEC
 more   …………   Display the contents of a file
 mrm   …………   IP Multicast Routing Monitor Test
 ncia   …………   Start/Stop NCIA Server
 ping   …………   Send echo messages
 pwd   …………   Display current working directory
 reload   …………   Halt and perform a cold restart
 restart   …………   Restart Connection
 resume   …………   Resume an active network connection
 rsh   …………   Execute a remote command
 sdlc   …………   Send SDLC test frames
 send   …………   Send a message to other tty lines
 setup   …………   Run the SETUP command facility
 show   …………   Show running system information
 start-chat   …………   Start a chat-script on a line
 telnet   …………   Open a telnet connection
 traceroute   …………   Trace route to destination
 undebug   …………   Disable debugging functions (see also 'debug')
 verify   …………   Verify a file
 write   …………   Write running configuration to memory, network, or terminal

This is just one part of the commands on the router series 1700 (and there are more)

After that you enter the Privileged mode, of course this is all assuming that you configure a completely non-configured router then from scratch.
One of the frequently used commands is "SHOW" by which we can see the configuration of the router or individual parameters.

Basic configuring Router serie 1721

For this occasion, I will configure router serie 1721 under the name the name 'Vinkovci-2' in Figure 9.

Figure 9.

How to configuring Cisco Router serie 1721

Before each configuration of the router, it is desirable to view the current configuration, for insight into the names of Interface and other parameters.

The current configuration of our Router looks like this: You notice that router 'Vinkovci-2' has one serial interface and 'Vinkovci-1' has two serial interface.

Router>
 Router>enable
 Router#show running-config
 Building configuration...
 !
 Version 12.1
 service timestamps debug uptime
 service timestamps log uptime
 no service password-encryption
 !
 hostname Router
 ip subnet-zero
 !
 interface Serial0
  no ip address
  no ip directed-broadcast
  shutdown
 !
 interface FastEthernet0
  no ip address
  no ip directed-broadcast
  bandwidth 100000
  shutdown
 !
 ip classless
 no ip http server
 !
 line con 0
  transport input none
 line aux 0
 line vty 0 4
 !
 no scheduler allocate
 end

Let's re-configure the router serie 1721

  Router>
  Router> enable // enter the Privileged mode
  Router # configure terminal // enter the global config mode
  Router (config) #hostname Vinkovci-2 // setting names Router
  Vinkovci-2 (config) #
  Vinkovci-2 (config) #banner motd # Welcome to Router Vinkovci-2 # // message of the day
  Vinkovci-2 (config) #line console 0 // entry into the console line mode
  Vinkovci-2 (config-line) #Password cisco // set password for entry through the console mode "cisco"
  Vinkovci-2 (config-line) #login // log in to set password
  Vinkovci-2 (config-line) #Exit
  Vinkovci-2 (config) #line vty 0 4 // set password to enter via telnet connection
  Vinkovci-2 (config-line) #Password cisco
  Vinkovci-2 (config-line) #login
  Vinkovci-2 (config-line) #Exit
  Vinkovci-2 (config) #enable password cisco // activate the password "cisco"
  Vinkovci-2 (config) #enable secret class // set password to enter Privileged mode
  Vinkovci-2 (config) #ip host Vinkovci-1 192.168.4.17 // name of the neighboring router and IP
  Vinkovci-2 (config) #Exit
  Vinkovci 2 # clock set 18:46:00 1 May 2006 // time setting on the router
  Vinkovci 2 # copy running-config startup-config // record configuration changes


This would be a basic initial configuration of the router 'Vinkovci-2'. See Figure9
To check the configuration we just made it is necessary to exit the Global config mode to Privileged mode and enter the command 'Vinkovci-2 # show running-config' to check the current configuration of the router.

When you run the command 'show running-config' on the router we have the following situation. It now looks like below:

Vinkovci-2#show running-config
 Building configuration...
 !
 Version 12.1
 service timestamps debug uptime
 service timestamps log uptime
 no service password-encryption
 !
 hostname Vinkovci-2
 enable secret 5 $sdf$6978yhg$jnb76sd
 enable password cisco
 !
 ip subnet-zero
 ip host Vinkovci-1 192.168.4.17
 !
 interface Serial0
  no ip address
  no ip directed-broadcast
  shutdown
 !
 interface FastEthernet0
  no ip address
  no ip directed-broadcast
  bandwidth 100000
  shutdown
 !
 ip classless
 no ip http server
 !
 banner motd ^C Welcome to Router Vinkovci-2 ^C
 line con 0
  login
  transport input none
  password cisco
 line aux 0
 line vty 0 4
  login
  password cisco
 !
 no scheduler allocate
 end

If you work with the AUX port, you need to set the password for a particular Aux port (similar to the "line console 0" or "line vty 0 4")

Since the router 'Vinkovci-2' DTE device will not be asking "clock rate", he is set to DCE device (Vinkovci-1), and the order is placed on the Serial1 interface in which the connected to the 'Vinkovci-2'.
The same is 'Vinkovci-1 (config-if) #clock rate 64000 // or example: 56000' This setting is required between two routers in a Point-to-Point Serial Connections because one router always DCE and the other DTE.

It remains to set the IP address to the interface of a (ports), be sure to activate them (ie. Include a layman's terms "UP") and set a description on Fast Ethernet ports to the LAN

Vinkovci-2 # configure terminal
Vinkovci-2 (config) #interface serial 0 // enter the Interface mode to serial port 0
Vinkovci-2 (config-if) #ip address 192.168.4.18 255.255.255.252 // set the IP address and subnet mask for a specific interface
Vinkovci-2 (config-if) #No shutdown // activate interfaces
Vinkovci-2 (config-if) #description Serial connection to Vinkovci-1 // setting description in the Interface
Vinkovci-2 (config-if) #Exit
Vinkovci-2 (config) #interface fastetheernet 0
Vinkovci-2 (config-if) #ip address 172.17.2.1 255.255.255.0
Vinkovci-2 (config-if) #No shutdown
Vinkovci-2 (config-if) #description LAN connection to the network 172.17.2.0
Vinkovci-2 (config-if) #Exit
Vinkovci-2 (config) #Exit
Vinkovci 2 # copy running-config startup-config


We have now completed the basic configuration of a Cisco router and it looks like this:

Vinkovci-2#show running-config
 Building configuration...
 !
 Version 12.1
 service timestamps debug uptime
 service timestamps log uptime
 no service password-encryption
 !
 hostname Vinkovci-2
 enable secret 5 $sdf$6978yhg$jnb76sd
 enable password cisco
 !
 ip subnet-zero
 ip host Vinkovci-1 192.168.4.17
 !
 interface Serial0
  description Serial connection to Vinkovci-1
  ip address 192.168.4.18 255.255.255.252
  no ip directed-broadcast
 !
 interface FastEthernet0
  description LAN connection to the network 172.17.2.0
  ip address 172.17.2.1 255.255.255.0
  no ip directed-broadcast
  bandwidth 100000
 !
 ip classless
 no ip http server
 !
 banner motd ^C
Welcome to Router Vinkovci-2 ^C
 line con 0
  login
  transport input none
  password cisco
 line aux 0
 line vty 0 4
  login
  password cisco
 !
 no scheduler allocate
 end

If you have ever imagined and wished to administer the Internet or LAN, I hope this tutorial will help you eventual hesitant to enroll or not the Cisco Networking Academy CCNA, or you have just started the course, so you these instructions may help in learning . Good luck administer IT network and re-configuration of the router.