Cisco IOS Basic Commands

Table Of Contents

     

  1. Introduction to using Cisco IOS Commands

     

  2. Getting Your Router Started
    1. Plugging Your Router In
    2. Router Parts
    3. What Happens When The Router Boots Up

     

  3. Logging On
    1. Command to create User Level Password
    2. Command to create Enable Password
    3. Command to create Enable Secret Password

     

  4. Making the IOS Shell Work For You
    * Recalling Command History and Editing Features

     

  5. Learning to use Context Sensitive Help
    * Using Help to create a Banner Headline.

     

  6. SHOWing Your Router's Elements
    * Using SHOW Commands.

     

  7. SHOWing Your Router Configurations
    * Main Cisco IOS Commands for looking at your Router.

     

  8. Commands to Save Your Configurations.
    * To Non-Volatile RAM Memory. Saving To TFTP Server.

     

  9. Commands to Reload From Saved Configuration Files.
    * From TFTP Server, From Flash Memory.

     

  10. Using the Setup Command

     

  11. Summary

HOME


The Storyline

You have just received your new Cisco Router by Express Delivery,
and you are sitting there admiring the wonderful Cisco box.

This tutorial is designed to use this scenario to explain
the Basic Cisco Internetwork Operating Commands.

As a side benefit it will also give step-by-step instructions
on how to carefully remove the Router from the Box
and set up it's initial configuration from scratch.


If you have a Used Router (not a brand-new Router) to work with,
and you want to follow along with this tutorial, you can blank out everything,
and start from what we call, "A Clean Slate".

(A Clean Slate refers back to a time when students wrote on slabs of rock)

Type in the following two Commands from the Enable Mode:

Erase Startup-config

Reload

 

DO NOT do these two commands on your company's production routers!
This will have very BAD consequences - i.e. "Network Down, You Fired!"


Helpful Learning Tips

  1. Entering Information into your Long-term Memory takes repetition. (aka Practice!)

  2. The More different ways you put the info into your Brain, the better.
    Don't just Read all this, get involved!
    • Read out loud, involving your voice and ears gives another pathway.
    • Fill in the blank Text boxes provided. Writing commands is good practice. .
    • Use your Imagination. It is your most powerful Learning Tool!

  3. Don't Study when tired. Exhausted Brains don't learn.

  4. Do take frequent Breaks.

  5. Try to learn One new concept at a time. Get it, then take a Break!

  6. Reward yourself for Studying. (I use Blueberries...)

  7. Don't expect it to be Easy. Cisco is anything but easy. Put in the work!

  8. Eat Lots of Blueberries! (I go through 2-4 pounds a week...)

Hope that this helps a bit!

1 - Introduction to using Cisco IOS Commands

Let's start out at the very beginning with the question:

"What is a Command?"

The most important thing to understand is that all computers run on Magic.
And that Commands are the Magic Words that make computers do things.
And that a Routers is merely a Computer in a box that does nothing but Route.

So what we are talking about here is the Magic Commands for Routing.
And you are going to become the Magician!

As long as you can remember the right Command,
then you will be able to make your Router do amazing tricks.

Forget the commands, mis-spell them, put them in the wrong place,
and you could call up evil Daemons that will destroy your network.

Yes, it is just like real magic - you will be playing with fire!

Most machines have commands and operating systems,
it's just that we normally don't think of them that way.

It's sort of just like your car.

First you need to get into it, so you use the "Key" command.
This allows you to open the door.
Cisco Routers use "Password" commands for this, but it's the same thing.

Then you have to use another Key command to start the car.

You have several commands that control what the car does.
There's the "Gas Pedal" Command that makes it go fast.
And the "Brake" Command that hopefully slows you down.
Of course it's good to have hands-on experience with the Steering Wheel,
which is a command that lets you adjust the direction you're going.

If Cisco had designed your car you would not have a Steering Wheel,
or Brakes, or a Gas Pedal. You would have a Text-Based User Interface.

Imagine being in your car and wanting to turn Right.

Instead of simply turning the wheel, you have to type in:

STEERING-WHEEL RIGHT 90

This Command consists of the Command word itself - STEERING-WHEEL
You also have the "Argument" - Right (which modifies the Command)
And then the "90" is another "Argument" standing for "90 Degrees"
If you had put in "180" then you'd have made a U-turn.

You could perhaps add the optional Argument, "Use-Turn-Signals".

Cisco would write the Model for this command like so:

STEERING-WHEEL {RIGHT | LEFT | STRAIGHT } number-of-degrees [[no] use-turn-signals]

Translating the way Cisco writes this command:
Everything in BOLD is what you write exactly as written.

STEERING-WHEEL is the Command itself. (notice the Boldface!)

An Argument is basically something which modifies the basic Command.

Things in Braces are Required Arguments {RIGHT | LEFT | STRAIGHT }
Notice that a Vertical Bar | separates the various choices.

Italics stand for Arguments for which You supply the Values.
number-of-degrees is an Argument that can be from 0 to 360 Degrees.

Square Brackets are for Optional Arguments - [[no] use-turn-signals]
Please note that the [no] is also in Brackets,
which simply means that it is also just an option.
(just say No to turn-signals?)

If you are feeling thankful that Cisco did not design your car,
just wait til we get to the Parallel Parking exercise!

Now then, there are 3 main types of Cisco Commands:

  1. Global Commands - Ones that make changes to the entire Router.
    "Look At Car" - car is leaning to one side.

  2. Major Commands - These allow parts of the Router to be configured.
    "Look At Tires" - front drivers side tire is flat.

  3. Subcommands - Do the actual work of configuring Router parts.
    "Change Tire" - getting out jack and spare, changing tire.

In order to configure most things on your Router,
you will need to use a combination of all 3 of these basic Command types.
Don't worry, you will soon become all-too-familiar with all 3!

But first things first, let's get your Router started!


2 - Starting Up Your Cisco Router

You have just received your brand-new Cisco Router by special delivery.

The first step is, in fact, to remove it from the box.
(We would suggest using a Chainsaw, but some of you would do it, right?)

The second step is to find all the wires and accessories.

If you are lucky and actually bought a Brand-new Router, you should have:

  • A Power Cord
  • A cable for connecting to a Computer port
  • A CD with all the Cisco Info in the World on it.
  • A manual (what's a manual, you ask? Who knows?)
If you bought a Used Second Hand Router and have all the Above
Count yourself as being one of the Luckiest people alive.

If you have said Manuals, read the Cisco "Getting Started Guide" now.

On the other hand, if you are Unlucky and do not have this manual,
but are using this Tutorial as a substitute, I will take mercy
and give you the "basic gist" of setting up a new machine.

First of all, Cisco is supposed to provide the cables
you need to connect your new Router to a Computer.
Find these wires, you will need them.

There should be a Port on the back of your Router that says "Console"

Find the cables that plugs into this port.
(it is usually an RJ45 connector or an RS-232-C connector)
(What? Did you expect Cisco to always use the Same connector??)

Plug the other end of said Cable into your Computer.
Once again, your Router & Computer mileage may vary -
you may need to find a suitable "connector adaptor" to make it fit.
Often seen are DB-9 , RS-232, or the good old RJ-45.

If you are confused right now, don't worry.
There is always some way to plug your Router into your Computer.

Anyway, let's say that you've figured this problem out
and have the appropriate Cable going between your New Router and your Computer.

 

Next step is to set the computer up with a "Terminal Emulation Program"
so that it can talk successfully with the Router. Sounds simple, right?

Well, there are lots of different computers and even more different terminal programs.
Most Windows computers come with a program called "HyperTerminal".
You can also download the latest version of this by searching the Net.

Luckily most of them agree on certain things which can be "set".

Anyway, set your Computer "Terminal Emulation Program" to the following:

  • VT100 Emulation
  • 9600 Baud
  • No Parity
  • 8 Data Bits
  • 1 Stop Bit

Some of you are already Experts and know what all these do.
If you don't know what these things mean, don't worry.
They will be appearing in my forthcoming 10,000 page Book "Everything About Computers"
available at fine bookstores near you by the year 3,000...

Anyway, where were we?

You have now connected your Computer to your Router. Congratulations!

The next step is easy.
Find the Router's Power Cord
Plug the Power Cord into an appropriate Electrical Socket.
Turn on Router! (hint, there should be a "Power Switch")

The next step should be visual.
See if the Power Light comes on
(on the 2500 series all you get is a little LED in back... sorry!)
(what's the point of owning expensive electronic gear without lots of blinking lights?)

There should also be a small fan noise. Some fans are louder than others.

Speaking of parts of the Router that blink and go "whirr"
We should now consider the important Internal Parts that you will be configuring!

 

Very Important Router Parts

  1. ROM - Read Only Memory.
    This is a form of permanent memory used by the Router to store:
    • The "Power-On Self Test" that checks the Router on boot up.
    • The "Bootstrap Startup Program" that gets the Router going.
    • A very basic form of the Cisco IOS software.
      (to change the ROM you have to remove and replace chips)

  2. Flash Memory
    An Electronically Erasable and Re-Programmable memory chip.
    The "Flash" contains the full Operating System, or "Image".
    This allows you to Upgrade the OS without removing chips.

  3. NVRAM - Non-Volatile RAM
    This stores your Router's "Startup Configuration File".
    Similar to Flash memory, this retains data even when power is lost.

  4. RAM - Random Access Memory
    This is regular computer memory chips.
    These are the working memory of the Router,
    and provide Caching, Packet Buffering, and hold Routing Tables.
    The RAM is also where the Running Operating System
    lives when the Router is on.
    RAM loses all its data when reset or powered off.

  5. Interfaces - Where the Router meets the Outside World.
    Basically your Router will have Serial interfaces,
    Which are mostly used to connect long-distance as in a WAN (Wide-Area Network).
    You will also have LAN (Local-Area Network) Interfaces,
    such as Ethernet, Token Ring, and FDDI (Fiber Distributed Data Interface)

What Happens As Your Router Boots Up

  1. The "Power-On Self-Test" checks the Router Hardware.
    This includes the CPU (Central Processor Unit), memory, and interfaces.

  2. The "Bootstrap Program", which is stored in ROM, runs itself

  3. The "Bootfield" is read to find out the proper Operating System source.

  4. The "Operating System Image" is loaded into RAM. (Random Access Memory)

  5. The "Configuration File" saved in NVRAM is loaded into the RAM.
    The Configuration File is then executed one line at a time.

  6. If no "Configuration File" is found in NVRAM,
    the Cisco IOS will offer you the chance to use the "Initial Configuration Dialog".
    This is a set of Questions for you to answer to do a basic configuration.
    Since in our theoretical New Router there is no NVRAM configuration
    This "Setup Dialog" will be one of the first things we see.

You should also start to see the following on your VT100 Terminal Program:

System Bootstrap, Version 12.0(1), SOFTWARE
Copyright (c) 1986-2001 by Cisco Systems

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... if you are viewing this at Home
please put your hands on your head an wait for the FBI to arrive.
(and other such legal fineprint as necessary!)

After reading this legal information very carefully,
a brand-new Router should enter automatically into what is
called the "System Configuration Dialog". Also called the "Setup Dialog".

It should ask you "Would you like to enter the initial configuration dialog? [yes|no]:"

But we are going to type in "NO" when it asks us if we want to use the
"System Configuration Dialog", because putting in the commands ourselves,
will let us learn exactly how to properly configure a Router.

Besides if you are a Cisco person, you like doing things the hard way!
As they always say, "The more difficult and challenging, the better!"

 

3 - Logging Onto Your Router

You have now gotten your Router turned on.
And you should have a good connection to your Terminal Program
The very next step should be to Log On.

But since we have a brand-new Router and you've turned down the Setup Dialog
there is no Password yet,

By Default, as it comes from the factory,
a Router does not require a password on the Console Port.

If you think this would be a terrible security flaw, you are correct!
You should definitely set up Passwords for your Router as your first step!
This initial "setting of password" can only be done from the Console Port.

Anyway, you should see a Prompt that says:

Router>

This is called User Exec Mode.
As a User you are allowed to log on, look at things, and do very little else.

You can not set up Passwords as a humble "User".
To set up Passwords for your Router you need to first enter what is called:

Privileged Exec Mode
(think of this as Master Magician Mode)

To enter Privileged Exec Mode type in the word enable at the prompt.

Router> enable
Router# . . . . . . .

This changes the prompt from Router> (with an arrow)
To Router# (with a # or pound sign.)
The # means that you have entered Privileged Exec Mode
Needless to say, nearly everyone just calls it "Enable Mode" for short.
You will very seldom hear anyone call it Privileged Exec Mode.

If you want to go back to being a plain User, just type disable

Now you are Enabled, a super-user with awesome mystical powers!
Please note that you did not need to enter a password
when logging in from the Console -
Nor did you need one when changing to Privileged Exec (Enable) Mode.

So you should Immediately set Passwords so that everyone else can not
just as easily become All-Powerful Deity. This would be Bad!

Just to keep this Tutorial simple, let's use "CISCO" for all the passwords.

But wait, in order to set passwords you must be in the right Mode!
In order to configure nearly anything on a Cisco Router
you must be in Configuration Mode.

To get from Enable Mode to Configuration Mode
try typing the word configure

Router# configure

You will then see on your terminal screen the question:

"Configuring from terminal, memory, or network [terminal]?"

If you press Return (or write in the magic word "terminal")
you will be able to configure from your terminal (aka computer).
(the other two choices are fun, but for now we'll use the terminal, ok?)

This will leave you at the unusual prompt:

Router(config)#

Which means that you are in the Router (Configure) mode.
Now and only now can you start the process of configuring Passwords.

Configure is a Global Command.

To go back to our car analogy, if Cisco passwords were Keys
you'd have to be in Car(config)# mode in order to use them.

Your very next step should be to set the Password for the Console Port.

Starting from within the Router(config) mode.
You need to put in the following series of commands to create one.

Router(config)# line console 0
Router(config-line)# login
Router(config-line)# password CISCO
Router(config-line#Ctrl-Z

Please do not use CISCO as a password in real life. This is just a Demo!

Note that the Router prompt changes to Router(config-line)
when you put in the line console 0 command.
line is a major command that puts you into "sub-command" mode.
(this is where you yell "Down Periscope - Dive! Dive! Dive!)
Only in the Router(config-line)# mode can you configure individual "lines".

Also note that the Ctrl-Z (Control-Z, also written ^Z) ends your session,
and brings you back up to the Router# prompt.

Remember that the 3 Types of Commands are
Global, Major, and Sub-command!

The Global Command "Configure" takes you down to Router(config) Mode.
The Major Command "Line select-interface takes you to Router(Config-line)
The Subcommands "login" and "password" let you configure your password.

But we are certainly not finished setting Passwords yet!
If Cisco Routers were simple easy-to-use devices,
everyone and his grandmother would be Cisco Certified, right?

There are 5 separate Passwords you need to protect your Router.

  1. Console - protects the Console Port

  2. Auxilary - protects the AUX Port (for your modem)

  3. TTY - Protects against un-authorized Telnet Port logons

  4. Enable - Guards the use of the Enable Mode Super-user status.

  5. Enable Secret - an Encrypted Secret form of the Above (better!)

We've done the Console already, so let's run through the rest briefly.
Just for fun, I am including text-boxes for you to write the Commands in.

Set the Auxiliary Password

Password for external modem connections

Router# (Type in the command config t )
Note that "config t" is interpreted by the Cisco IOS same as "Configure Terminal"
Most commands can be entered in abbreviated form,
and even better you can press the "Tab" key to complete commands!

This gives you the following Prompt:
Router(config)# (Type in line aux 0
which takes you down to the mode to configure "line auxiliary 0" (zero).

Now you can start using the sub-commands to configure the Aux port.

Router(config-line)# (Type in login)

Router(config-line)# ( password your-aux-password-here)

Router(config-line)# Ctrl-Z

Router#

And now your Router has a password protecting the AUX port.

Setting Passwords on the Virtual (VTY) Ports

VTY Ports are rather a special case, since they are not real ports.
In other words, you won't find a Port on the back of your Router labeled VTY.

They are what could be called "Virtual Ports" that wait patiently
for a Remote Connection, usually using Telnet, to log in.

If you don't set these, you won't be able to Telnet in to your Router.
This means every time your routers have a problem, you have to drive in to work.
Or to where-ever the routers may be hidden (like Timbuktu?).

Configuring the VTY password is very similar to doing the Console and Aux ones.

The only difference is that there are 5 VTY virtual ports,
which are named 0, 1, 2, 3, and 4 .
You can use the shortcut 0 4 (a zero, a space, and 4) to set all 5 passwords at the same time.

Router# (type in config t)

Router(config)# (type in line vty 0 4)

Router(config-line)# (type in login)

Router(config-line)# (type in password VTY-Password-here)

This concludes setting your VTY Passwords!
(you can type in Ctrl-Z to go back to plain Enable Mode)
Router(config-line)# Ctrl-Z
Router#

Setting Your "Enable" Password

The Enable is the old form of the password that guards
the Exec Command Interpreter's "Privileged Mode".
Which as we mentioned earlier is usually called "Enable Mode"
since that is the word you type in to get to it.

Usually with newer equipment you'll be using the "Enable Secret",
which is a better password because it is stored in an encrypted form.

However, it is best to also set an Enable Password
because if for some reason your computer has to boot up into an old version
of the Cisco IOS (say for problems that make it go into ROM mode, eh?)
then the "Enable Secret" won't work. But the old-fashioned "Enable" will!

By now this should be getting familiar to you,
but remember that "Repetition helps you Memorize!"

Once again start out with the Router in "Enable" (or "Privileged") mode.

From the Command Prompt issue the Global Command configure terminal

Router# (type in config t)

Router(config)# (type in enable password your-enable-password)

That's all, it's done, even easier than before!
Notice that you are Not configuring a Line here, but the whole Router!
(that's why you didn't need to type in a "line..." command)

Again you can now do a Ctrl-Z to get back to your "Router#" prompt.

Setting Your "Enable Secret" Password

The "Enable Secret" password, as mentioned above, is an advanced form
of a "one-way cryptographic secret password".

In other words, once you put in the plain text password,
the Cisco IOS takes the text and encrypts it so that no one,
not even you, can ever read it again.

This is why it is good advice Not to forget your Enable Secret Password!

The Router doesn't like the Enable Secret to be the same as the Enable.

Router(config)#enable secret CISCO
The enable secret you have chosen is the same as your enable password.
This is not recommended. Re-enter the enable secret.

So let us make the Enable Secret password CISCO2 instead.

The Enable Secret takes over from the regular Enable password.
This means if you set an Enable Secret Password, your Enable one will NOT work.

So Don't Forget Your Password!
(Reminder, your Password for everything in this tutorial is CISCO)

Again, this is a simple set of commands:

Router# (type in config t)

Router(config)#
(type in enable secret your-enable-secret-password)

That's really all it takes. Don't forget it!
Again do a Ctrl-Z to exit.
This will put you back at the Global Enable Mode Prompt:

Router#

Practice Logging On and Off

Now that you have successfully entered all the Passwords your Router needs,
this is a good time to do a quick practice session.

To leave the Enable Mode you need to type in the word disable
Remember again that Enable Mode is formally called "Privileged Exec Mode".

Router# (type in disable)

This will leave you at the User Exec Mode prompt:

Router >

Now we are going to leave and say "Quit" or "Exit" to our Router:

Router > (type in exit or quit)

You will now see the friendly message:

"Press ENTER to get started."

Okay, at this point you would go ahead and press the ENTER key.

The next thing you will see on the screen will be:

User Access Verification
Password (please type in your User Password here)
Router >

You quickly recognize the "Router >" at the User Exec Level Prompt.

Router > (now type in your Enable Secret Password)

If you typed in your enable Secret Password correctly
you should now be in the all-powerful Privileged Exec Mode!
(better known as Enable Mode to us common folk)

Router#

Congratulations! You have now set up your Router, created Passwords,
and successfully logged back into it.

Please note: Do Not Forget Your Passwords!


4 - Making The IOS Shell Work For You

For those of you who consider UNIX to be an easy and user-friendly thing,
you will be pleased to note that the creators of the Cisco IOS liked UNIX.

If you are like the rest of mankind and think of UNIX as User-Hostile,
then take hope from the fact that Cisco doesn't use ALL the UNIX commands.

I have it on good authority that the people who designed the Cisco IOS
liked to use the BASH Shell, a UNIX shell that is fairly polite.

And they very much liked using the standard editing program "vi".
(which may stand for "Variable Insanity" or "Very Intense"...)

Anyway, if you've worked for years with BASH shells and "vi" you're in luck.

If you haven't, here are the simple Operating Instructions.


Simple Operating Instructions

  • CTRL-A goes to the "Beginning" of the Line.

  • CTRL-E goes to the "End" of the Line.

  • CTRL-B go "Back One Character". (can also use LEFT Arrow key)

  • CTRL-F go "Forward One Character". (can also use RIGHT Arrow key)

  • ESCAPE-B go "Backward to the Beginning of the Next Word".

  • ESCAPE-F go "Forward to the Beginning of the Next Word".

Note that using the ARROW Keys is limited to those using a VT-100 Terminal Emulation.


Fancy Editing Tricks

If the end of a line goes too long, it will not automatically wrap to the next one.

Instead the Cisco IOS command shell gives you a dollar sign $.
This indicates that you are an over-achiever and have typed too much,
at least too much to be shown on the screen.

Your line would now look like this:

Router#$ this is a way too long line that is full of sound and fury

Note that the $ goes after the Router Prompt.

If you keep typing is will shift over as you type,
hiding more of the beginning of the sentence.

Router#$long line that is full of sound and fury, signifying nothing!

You can get back to the beginning of your Novel by typing CTRL-A

Router# For Demo Purposes Only this is a long line that is full of $

If you want to you can turn off these Advance Editing Tools
by implying typing in Terminal No Editing at the prompt.

Since this would be a silly thing to do, please turn them back on
by typing in the two words Terminal Editing.


Command History!

Now then, you just typed in a Real Long Command (RLC)
and you realize that you made a mistake in one word
and want a second chance to do it right again.

Well, the Cisco IOS makes this Real Easy!

The Router keeps the last 10 commands you issued in its HISTORY,
which is a special memory Buffer which holds the "Command History".
(note here that a "Buffer" is a memory space for storing things...)

If you are using the VT-100 Emulator we talked about before,
simply do the following.

  • Press the UP Arrow key to go back to the previous command.

  • Press the DOWN Arrow key to go back to the previous command.

If you are a poor unfortunate without VT-100 you can use these instead:

  • CTRL-P takes you to the "Previous" command.

  • CTRL-N takes you to the "Next" commands.

Putting the Command show history in at the prompt
gives you the list of the last 10 commands you have typed in.

Router# show history

  1. Command One

  2. Command Two

  3. Command Three

  4. Command Four

  5. Command Five

  6. Command Sixx - (with a mistake!)

  7. Command Six - (fixed now)

  8. Command Eight - "There is No Command 7!"

  9. Command Nine

  10. Command Ten

You can increase the size of your HISTORY buffer by using the command:

Terminal History Size

Router# Terminal History Size 99

The above command would give you 99 commands to play with!

Hope you noticed the SHOW part of the command above,
we will be using a lot more of SHOW commands to look at various things!


5 - Learning To Use Context Sensitive Help

There are always times when even the most Expert Networking person
needs to bring back to mind one of those 10,001 arcane commands
that are always the exact one you need and can't remember.

For us poor Mortals we can rejoice in the fact that the Cisco IOS
has a very good "HELP" function built into it.

It is called Context Sensitive Help

"Help" means that it actually provides some assistance.

means that the commands it offers you
change with the "context" or basically "what you are trying to do".

A more scientific description would be:

Where you are currently in the Router Command Shell

In other words, a person in User Exec mode would only see a few commands.

A person in Privileged (Enable) Mode would see lots more command options.

In the Global Prompt Router# you would see "Global Commands"

If you drop down into Config-t you'd see "Configuration Commands"

And so on, etc. and the like...

 

Secrets of Using HELP!

Using the Help function is as easy as typing in a Question Mark.

?

There are 3 main uses of the Question Mark.

1. If you type in a "?" at a Router prompt,
the Help function gives you a list of all the commands you can use from that Prompt.

2. If you type in a command, a Space, and then a Question Mark (?)
The Cisco IOS will try and give you options you can use with that command.

3. If you type in the first few letters of a command and a Question Mark
the IOS will give you a list of Commands that start with those letters.
(please note there is No Space between the letters and the ? - Important!)


Using HELP to make a Banner

Telling you how "Context Sensitive Help" works is nice,
but a simple example of how to use it should make it clearer.

A Banner is simply a message that pops up on the screen
it is related to the old UNIX "Message of the Day" or MOTD.

In order to set a Banner you have to be in Router Config mode.

Let's start out at the User Exec prompt and look for "Configure"
(remember that User Exec is limited and has No Privileges!)

Router>? (here is where you type in the Question Mark)
Exec commands:

access-enable
clear
connect
disconnect
disable
enable
exit
help
lat
lock
login
logout

Create a temporary Access-List entry
Reset functions
Open a terminal connection
Disconnect an existing network connection
Turn off privileged commands
Turn on privileged commands
Exit from the EXEC
Description of the interactive help system
Open a lat connection
Lock the terminal
Log in as a particular user
Exit from the EXEC

Here you will note two things:

1. There is no "Configure" command listed for User Exec Mode
(Like we said, you can't do much as a poor ordinary User!)

2. There is an "Enable" command to get you into Enable Mode. (Privileged!)

3. The list ends up with the word "--more--"
Which simply means that there are more commands not yet listed.
If you press the "Return" key you'll get another screen full of commands,
but since they are in alphabetical order,
you already know "Configure" is not an available command.

Anyway, let's take the hint and get into Enable Mode.

Router> (type in the command enable)

Router# (note again that the Prompt sign changes to a # symbol)

Now let's see what new and different commands are available!

Router# Type in a ?

Router#?
Exec commands:

access-enable
access-template
bfe
clear
clock
configure
connect
copy
debug
disable
disconnect
enable
erase
exit
help

Create a temporary Access-List entry
Create a temporary Access-List entry
For manual emergency modem setting
Reset functions
Manage the system clock
Enter configuration mode
Open a terminal connection
Copy configuration or image date
Debugging functions (see also "undebug")
Turn off privileged commands
Disconnect an existing network connection
Turn on privileged commands
Erase flash or configuration memory
Exit from the EXEC
Description of the interactive help system

Notice that in the Privileged (Enable) Mode you have different commands.
From here it is possible to enter the Global command configure
and begin to actually change the configuration of your router!

Just to show more of the Help functions, how about we type in:

configure (space) ? (the empty space is Very Important!)

Router# (type in configure ? here)

This will give us a list of the "Options" for the configure command.

Router#configure ?

Memory
Network
Terminal

This gives us the 3 choices of places to load a configuration from.
Mostly we've just been using the Terminal, since we are doing setup,
but we'll later show you how to use the Network or Memory to load Configs.

In order to properly configure your Router's various Elements
it is good to get familiar with what they are and how you can show them.
So next let's take a closer look at our Router's Elements
using the all-important "Show" commands.



6 - Showing Off Your Routers Elements


Using The SHOW Commands

Most SHOW command can be viewed from the regular USER Exec mode.
Some SHOW commands can only be viewed from the Privileged Exec (Enable) mode.

None of the SHOW commands can be used from the (config) mode.
This will just give you an error and you will feel very silly!

If you've been busily configuring stuff like Interfaces and Protocols,
and forget to change back to the plain old Router# or Router prompt
using a Show command will not work. All you get is an error message.

Router# show _______ (right!)

Router(config-if)# show _______ (wrong!)

If you type in the command Show, a space, and then a Question Mark,
at the proper Enable Mode "Router#" prompt,
the Help function will give you a long list of the multitudinous show commands.

Router#show ?

show access-expression
show access-list
show apple interface
show apple route
show appletalk
show atm
show bridge
show cam
show cam dynamic
show cdp neighbors
show config

And so on going down through the entire alphabet...!

Luckily, you do not need to memorize all these right away for the tests.

There are, however, several show commands that are very useful
for taking a closer look at what your router has in it and what it's doing.


Show Version

The show version command gives you information on what version
of the Cisco Internetwork Operating System your router is using.
It also gives you lots of other basic information on things such as
"how long the router has been up", "how the system was started",
"what processor" and "how much memory" and "where the system image file was loaded from."

Show version will also show you what interfaces the router has.

router# type in show version
(you can also type in sh ver for short)

Router> (type in show version

router>show version

Cisco Internetwork Operating System Software
IOS (tm) 3000 software (IGS-I-L, Version 11.1(11) RELEASE SOFTWARE (fc1)
Copyright (c) 1986-1999 by Cisco Systems, Inc.
Compiled Tue 24-Jun-97 12:20 by jaturner
Image text-base: 0x0301E644, data-base 0x00001000

ROM: System Bootstrap, Version 11.0(10c), SOFTWARE
ROM: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c) RELEASE SOFTWARE (fc1)

Router uptime is 12 minutes
System restarted by power-on
System image file is "flash:igs-i-l.110-16", booted via flash

Cisco 2500 (68030) processor (revision N) with 2048K/2048K bytes of memory.
Processor board ID 06267777, with hardware revision 00000000

Bridging software
X.25 software, Version 2.0, NET2,, BFE and GOSIP compliant.

1 Ethernet/IEEE 802.3 interface.
2 Serial network interfaces.

32K bytes of non-volatile configuration memory.
8192K bytes of processor board System flash (Read ONLY)

Configuration register is 0x2102


Show Memory

The show memory command shows what memory is allocated
by the management system for which purposes.

Router> (type in show memory)

Router>show memory

There are two Memory Charts that get shown.

1. A Summary

Router>:show memory

Head Total(b) Used(b) Free(b) Lowest(b) Largest(b)
Processor EA90C 5326580 2056220 3270360 3270360 3231192
I/O 600000 2097152 465264 1631888 1579032 1631720

2. A Detailed Block by Block memory chart.

Allocator PC Summary for: Processor

pc=0x031FDE54, size=000963416, count=000056, name=List Elements
pc=0x031D8060, size=000462508, count=000312, name=*Packet Data*
pc=0x03217BAE, size=000287992, count=000068, name=Interrupt Stack
pc=0x031D8028, size=000178496, count=000312, name=*Packet Header*
pc=0x031DCDEC, size=000115040, count=000008, name=Fair Queuing
pc=0x031C2BD2, size=000049196, count=000001, name=Exec
pc=0x031DDBA8, size=000044660, count=000011, name=*Hardware IDB*
pc=0x031957E4, size=000040840, count=000010, name=TTY data
pc=0x03214150, size=000033516, count=000063, name=Process
pc=0x0322E6F4, size=000032808, count=000001, name=Cfg EEPROM Copy
pc=0x031DDBBE, size=000025124, count=000011, name=*Software IDB*
pc=0x034A829A, size=000014468, count=000001, name=Init
pc=0x034A81F4, size=000014464, count=000001, name=Init
pc=0x03AA68C2, size=000013644, count=000001, name=Init
pc=0x03A772B6, size=000013644, count=000028, name=ATMSIG-SHOW
pc=0x031A2D10, size=000013512, count=000197, name=Parser
01:13:41: %SYS-3-CPUHOG: Task ran for 2008 msec (19/19), process = Exec, PC = 31 7A068.

-Traceback= 320F2A6 317A070 318F4A4 31904A2 318F54C 31C2EBE
31C3028 31C3332 31A18F0 31B605C Linkage
pc=0x031368E0, size=000012044, count=000001, name=Init
pc=0x0320BCD8, size=000012032, count=000084, name=Watched Boolean
pc=0x032B17D0, size=000011420, count=000001, name=DHCPD Message Workspace
pc=0x0320BEE8, size=000011040, count=000064, name=Process Events
--More--

As you can see the SHOW MEMORY command gives you lots of detailed information
about the memory contained within your router.


Show Processes

A Process is part of a Program, or if it is small, it can be the entire Program.

It's sort of like having a troupe of Jugglers,
each item they are tossing up in the air is one Process.
As long as they keep them all going, everything is fine.
If not you can use SHOW PROCESSES to do a little troubleshooting!

The show processes command shows you all the active processes,
in the form of a chart containing the following information in Columns:

PID - The ID number of each Process.

Q - The Queue priority

TY - This is the Status of the Process

PC - Program Counter.

Runtime - The amount of CPU time in milliseconds used by the Process

Invoked - This is the amount of time the Process has been invoked.

uSecs - The CPU time in milliseconds for each Process invocation.

Stacks - This shows both the "low watermark" / "total stack space" in bytes.

TTY - Shows you which terminal controls the process.

Process - Finally, this actually gives you the Name of the process!

Router> (type in show processes

Router>show processes 

CPU utilization for five seconds: 7%/7%; one minute: 9%; five minutes: 12%

PID QTy PC Runtime (ms) Invoked uSecs Stacks TTY Process

1 Csp 32134FE 8 872 9 736/1000 0 Load Meter

2 M* 0 3632 82 44292 2960/4000 0 Exec

3 Lst 3203DC6 14300 960 14895 3736/4000 0 Check heaps

4 Cwe 3209FB6 0 1 0 3724/4000 0 Pool Manager

5 Mst 318E706 0 2 0 3700/4000 0 Timers

6 Mwe 311F992 8 2 4000 3696/4000 0 Serial Background

7 Lwe 323C858 340 78 4358 3684/4000 0 ARP Input

8 Mwe 33877A6 0 3 0 3704/4000 0 DDR Timers

9 Mwe 339B8CA 0 2 0 5712/6000 0 Dialer event

10 Lwe 34BE0AC 36 2 18000 3684/4000 0 Entity MIB API

11 Mwe 3125CA2 0 1 0 3732/4000 0 SERIAL A'detect

12 Cwe 320D770 0 1 0 3740/4000 0 Critical Bkgnd

13 Mwe 31E55AA 696 547 1272 4756/6000 0 Net Background

14 Lwe 31857B2 16 7 2285 5604/6000 0 Logger

15 Msp 319E1D4 172 4347 39 3568/4000 0 TTY Background

16 Msp 31E4EB6 3084 4415 698 3736/4000 0 Per-Second Jobs

17 Msi 3235488 40 4351 9 3724/4000 0 Partition Check

18 Hwe 31E5014 0 1 0 3712/4000 0 Net Input

19 Csp 31EC442 68 873 77 3728/4000 0 Compute load avg

20 Msp 31E4EE4 4740 75 63200 3776/4000 0 Per-minute Jobs

21 Mwe 309D71E 0 1 0 3824/4000 0 SYNCCD2430 Help

--More--


SHOW STACKS

A Stack is basically a portion of the Memory that is used to monitor
the internal operations of a program.

Stacks are usually ordered in a "Last In, First Out" (LIFO) data structure.

The SHOW STACKS command looks at the manner in which the Cisco Router's
Processes and Interupts utilize these stacks.

If there was a Reboot caused by a crash, then using SHOW STACKS
will reveal the reason for that reboot.

Router> (type in show stacks 

Router>show stacks

Minimum process stacks:
Free/Size Name
2704/4000 Setup
3256/4000 Autoinstall
2776/4000 DNS Snoop
2680/4000 Init
1720/2000 LAPB Timer
5400/6000 BootP Resolver
3460/4000 RADIUS INITCONFIG
4632/5000 DHCP Client
3524/4000 Exec

Interrupt level stacks:

Level Called Unused/Size Name
1 0 3000/3000 CL-CD2430 transmit interrupts
2 0 3000/3000 CL-CD2430 receive interrupts
3 33 2772/3000 Serial interface state change interrupt
4 23 2872/3000 Network interfaces
5 10771 2896/3000 Console Uart


SHOW BUFFERS

A Buffer is portion of Memory set aside for data to wait around in
while waiting to catch the next bus out.

Buffers are sort of like Bus Stops, but some are Bigger (like a Bus Station),
and some of them are very large, like an Airport!

SHOW BUFFERS lets you see the size of the Small, Middle, Big, Very Big, Large, and Huge buffers.

Also gives statistics on their usage. Kind of like Baseball scores.

Router> (type in show buffers 

Router>show buffers



                            Buffer elements:

500 in free list (500 max allowed)
128 hits, 0 misses, 0 created

Public buffer pools:
Small buffers, 104 bytes (total 56, permanent 50):
54 in free list (20 min, 150 max allowed)
87 hits, 2 misses, 0 trims, 6 created
0 failures (0 no memory)
Middle buffers, 600 bytes (total 28, permanent 25):
28 in free list (10 min, 150 max allowed)
76 hits, 1 misses, 0 trims, 3 created
0 failures (0 no memory)
Big buffers, 1524 bytes (total 50, permanent 50):
47 in free list (5 min, 150 max allowed)
19 hits, 0 misses, 0 trims, 0 created
0 failures (0 no memory)
VeryBig buffers, 4520 bytes (total 10, permanent 10):
10 in free list (0 min, 100 max allowed)
0 hits, 0 misses, 0 trims, 0 created
0 failures (0 no memory)
Large buffers, 5024 bytes (total 0, permanent 0):
0 in free list (0 min, 10 max allowed)
0 hits, 0 misses, 0 trims, 0 created
0 failures (0 no memory)
Huge buffers, 18024 bytes (total 0, permanent 0)
: 0 in free list (0 min, 4 max allowed)
0 hits, 0 misses, 0 trims, 0 created
0 failures (0 no memory)

Interface buffer pools:
Ethernet0 buffers, 1524 bytes (total 32, permanent 32):
8 in free list (0 min, 32 max allowed)
24 hits, 0 fallbacks
8 max cache size, 8 in cache
BRI0 buffers, 1524 bytes (total 4, permanent 4):
3 in free list (0 min, 4 max allowed)
3 hits, 0 fallbacks
1 max cache size, 1 in cache
BRI0:1 buffers, 1524 bytes (total 16, permanent 16):
12 in free list (0 min, 16 max allowed)
12 hits, 0 fallback
4 max cache size, 4 in cache
BRI0:2 buffers, 1524 bytes (total 16, permanent 16):
12 in free list (0 min, 16 max allowed)
12 hits, 0 fallbacks

4 max cache size, 4 in cache
Serial0 buffers, 1524 bytes (total 32, permanent 32):
7 in free list (0 min, 32 max allowed)
25 hits, 0 fallbacks
8 max cache size, 8 in cache
Serial1 buffers, 1524 bytes (total 32, permanent 32):
7 in free list (0 min, 32 max allowed)
25 hits, 0 fallbacks
8 max cache size, 8 in cache
Serial2 buffers, 1524 bytes (total 8, permanent 8)
: 6 in free list (0 min, 8 max allowed)
6 hits, 0 fallbacks
0 max cache size, 0 in cache
Serial3 buffers, 1524 bytes (total 8, permanent 8):
6 in free list (0 min, 8 max allowed)
6 hits, 0 fallbacks
0 max cache size, 0 in cache
CD2430 I/O buffers, 1524 bytes (total 20, permanent 20):
10 in free list (0 min, 20 max allowed)
10 hits, 0 fallbacks


SHOW FLASH

We'd already discussed what Flash Memory is early, but a reminder can't hurt.

Flash Memory
An Electronically Erasable and Re-Programmable memory chip.
The "Flash" contains the full Operating System, or "Image".
This allows you to Upgrade the OS without removing chips.

SHOW FLASH tells you how Big the Flash Memory is and what it is doing.
Again lots of good statistics to use in troubleshooting your Router.

Router> (type in show flash 

Router>show flash

System flash directory:
File Length Name/status
1 11780820 12-04T.bin
[11780884 bytes used, 4996332 available, 16777216 total]
16384K bytes of processor board System flash (Read ONLY)


SHOW INTERFACES

SHOW INTERFACES is like the Swiss Army knife of troubleshooting.
It gives you information on all the Interfaces in your Router.
Since the Interfaces are where all the real work takes place
being able to see what they are doing is very helpful.

Router> (type in show interfaces

Router>show interfaces 

BRI0 is administratively down, line protocol is down







  Hardware is BRI







  MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,







     reliability 255/255, txload 1/255, rxload 1/255







  Encapsulation HDLC, loopback not set







  Last input never, output never, output hang never







  Last clearing of "show interface" counters never







  Input queue: 0/75/0 (size/max/drops); Total output drops: 0







  Queueing strategy: weighted fair







  Output queue: 0/1000/64/0 (size/max total/threshold/drops)







     Conversations  0/0/256 (active/max active/max total)







     Reserved Conversations 0/0 (allocated/max allocated)







  5 minute input rate 0 bits/sec, 0 packets/sec







  5 minute output rate 0 bits/sec, 0 packets/sec







     0 packets input, 0 bytes, 0 no buffer







     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles







     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort







     0 packets output, 0 bytes, 0 underruns







     0 output errors, 0 collisions, 5 interface resets







     0 output buffer failures, 0 output buffers swapped out







     0 carrier transitions







BRI0:1 is administratively down, line protocol is down







  Hardware is BRI







  MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,







  Encapsulation HDLC, loopback not set







     reliability 255/255, txload 1/255, rxload 1/255







  Encapsulation HDLC, loopback not set







  Keepalive set (10 sec)







  Last input never, output never, output hang never







  Last clearing of "show interface" counters never







  Input queue: 0/75/0 (size/max/drops); Total output drops: 0







  Queueing strategy: weighted fair







  Output queue: 0/1000/64/0 (size/max total/threshold/drops)







     Conversations  0/0/256 (active/max active/max total)







     Reserved Conversations 0/0 (allocated/max allocated)







  5 minute input rate 0 bits/sec, 0 packets/sec







  5 minute output rate 0 bits/sec, 0 packets/sec







     0 packets input, 0 bytes, 0 no buffer







     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles







     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort







     0 packets output, 0 bytes, 0 underruns







     0 output errors, 0 collisions, 5 interface resets







     0 output buffer failures, 0 output buffers swapped out







     0 carrier transitions







BRI0:2 is administratively down, line protocol is down







  Hardware is BRI







  MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,







     reliability 255/255, txload 1/255, rxload 1/255







  Encapsulation HDLC, loopback not set







  Keepalive set (10 sec)







  Last input never, output never, output hang never







  Last clearing of "show interface" counters never







  Input queue: 0/75/0 (size/max/drops); Total output drops: 0







  Queueing strategy: weighted fair







  Output queue: 0/1000/64/0 (size/max total/threshold/drops)







     Conversations  0/0/256 (active/max active/max total)







     Reserved Conversations 0/0 (allocated/max allocated)







  5 minute input rate 0 bits/sec, 0 packets/sec







  5 minute output rate 0 bits/sec, 0 packets/sec







     0 packets input, 0 bytes, 0 no buffer







     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles







     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort







     0 packets output, 0 bytes, 0 underruns







     0 output errors, 0 collisions, 5 interface resets







     0 output buffer failures, 0 output buffers swapped out







     0 carrier transitions







Ethernet0 is administratively down, line protocol is down







  Hardware is Lance, address is 0010.7b3a.dea6 (bia 0010.7b3a.dea6)







  MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,







     reliability 252/255, txload 1/255, rxload 1/255







  Encapsulation ARPA, loopback not set







  Keepalive set (10 sec)







  ARP type: ARPA, ARP Timeout 04:00:00







  Last input never, output 01:17:16, output hang never







  Last clearing of "show interface" counters never







  Queueing strategy: fifo







  Output queue 0/40, 0 drops; input queue 0/75, 0 drops







  5 minute input rate 0 bits/sec, 0 packets/sec







  5 minute output rate 0 bits/sec, 0 packets/sec







     0 packets input, 0 bytes, 0 no buffer







     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles







     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored







     0 input packets with dribble condition detected







     14 packets output, 840 bytes, 0 underruns







     14 output errors, 0 collisions, 1 interface resets







     0 babbles, 0 late collision, 0 deferred







     14 lost carrier, 0 no carrier







     0 output buffer failures, 0 output buffers swapped out







Serial0 is administratively down, line protocol is down







  Hardware is HD64570







  MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,







     reliability 255/255, txload 1/255, rxload 1/255







  Encapsulation HDLC, loopback not set







  Keepalive set (10 sec)







  Last input never, output 01:17:18, output hang never







  Last clearing of "show interface" counters 01:17:18







  Queueing strategy: fifo







  Output queue 0/40, 0 drops; input queue 0/75, 0 drops







  5 minute input rate 0 bits/sec, 0 packets/sec







  5 minute output rate 0 bits/sec, 0 packets/sec







     0 packets input, 0 bytes, 0 no buffer







     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles







     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort







     5 packets output, 853 bytes, 0 underruns







     0 output errors, 0 collisions, 2 interface resets







     0 output buffer failures, 0 output buffers swapped out







     0 carrier transitions







     DCD=down  DSR=down  DTR=down  RTS=down  CTS=down







Serial1 is administratively down, line protocol is down







  Hardware is HD64570







  MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,







     reliability 255/255, txload 1/255, rxload 1/255







  Encapsulation HDLC, loopback not set







  Keepalive set (10 sec)







  Last input never, output 01:17:50, output hang never







  Last clearing of "show interface" counters never







  Input queue: 0/75/0 (size/max/drops); Total output drops: 0







  Queueing strategy: weighted fair







  Output queue: 0/1000/64/0 (size/max total/threshold/drops)







     Conversations  0/2/256 (active/max active/max total)







     Reserved Conversations 0/0 (allocated/max allocated)







  5 minute input rate 0 bits/sec, 0 packets/sec







  5 minute output rate 0 bits/sec, 0 packets/sec







     0 packets input, 0 bytes, 0 no buffer







     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles







     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort







     6 packets output, 132 bytes, 0 underruns







     0 output errors, 0 collisions, 3 interface resets







     0 output buffer failures, 0 output buffers swapped out







     23 carrier transitions







     DCD=down  DSR=down  DTR=down  RTS=down  CTS=down







Serial2 is administratively down, line protocol is down







  Hardware is CD2430 in sync mode







  MTU 1500 bytes, BW 115 Kbit, DLY 20000 usec,







     reliability 255/255, txload 1/255, rxload 1/255







  Encapsulation HDLC, loopback not set







  Keepalive set (10 sec)







  Last input never, output never, output hang never







  Last clearing of "show interface" counters never







  Input queue: 0/75/0 (size/max/drops); Total output drops: 0







  Queueing strategy: weighted fair







  Output queue: 0/1000/64/0 (size/max total/threshold/drops)







     Conversations  0/0/256 (active/max active/max total)







     Reserved Conversations 0/0 (allocated/max allocated)







  5 minute input rate 0 bits/sec, 0 packets/sec







  5 minute output rate 0 bits/sec, 0 packets/sec







     0 packets input, 0 bytes, 0 no buffer







     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles







     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort







     6 packets output, 1992 bytes, 0 underruns







     0 output errors, 0 collisions, 2 interface resets







     0 output buffer failures, 0 output buffers swapped out







     0 carrier transitions







     DCD=down  DSR=down  DTR=down  RTS=down  CTS=down







Serial3 is administratively down, line protocol is down







  Hardware is CD2430 in sync mode







  MTU 1500 bytes, BW 115 Kbit, DLY 20000 usec,







     reliability 255/255, txload 1/255, rxload 1/255







  Encapsulation HDLC, loopback not set







  Keepalive set (10 sec)







  Last input never, output never, output hang never







  Last clearing of "show interface" counters never







  Input queue: 0/75/0 (size/max/drops); Total output drops: 0







  Queueing strategy: weighted fair







  Output queue: 0/1000/64/0 (size/max total/threshold/drops)







     Conversations  0/0/256 (active/max active/max total)







     Reserved Conversations 0/0 (allocated/max allocated)







  5 minute input rate 0 bits/sec, 0 packets/sec







  5 minute output rate 0 bits/sec, 0 packets/sec







     0 packets input, 0 bytes, 0 no buffer







     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles







     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort







     6 packets output, 1992 bytes, 0 underruns







     0 output errors, 0 collisions, 2 interface resets







     0 output buffer failures, 0 output buffers swapped out







     0 carrier transitions







     DCD=down  DSR=down  DTR=down  RTS=down  CTS=down


SHOW PROTOCOLS

A Protocol is an agreed-upon method of speaking to others.
Sort of like having a conference call and all of us agreeing,
"Let's all speak Swahili..."

SHOW PROTOCOLS lets you know if everyone is speaking Swahili properly.
If they are not, then the Router will tell you, "Line Protocol is down.

Even if the Interface is UP, if the Line Protocol isn't working, nothing works.

All of our Interfaces will be listed as Administratively Down
since we have not yet turned any of them on.

In fact, since we are only doing the basic Setup of one Router in this tutorial,
we don't actually have anyone else to talk Swahili with, do we?

Router> (type in show protocols)

Router>show protocols

Global values:

Internet Protocol routing is enabled
BRI0 is administratively down, line protocol is down
BRI0:1 is administratively down, line protocol is down
BRI0:2 is administratively down, line protocol is down
Ethernet0 is administratively down, line protocol is down
Serial0 is administratively down, line protocol is down
Serial1 is administratively down, line protocol is down
Serial2 is administratively down, line protocol is down
Serial3 is administratively down, line protocol is down


SUMMARY

As you can see, the SHOW commands give you an inside view of your router.
There are many, many show commands, and you will get to know most of them!

 

7 - SHOWing Your Router Configurations

There are two main SHOW commands that allow you to see your Router's
full configurations, in other words, "Everything they are set up to do."

One is SHOW STARTUP-CONFIG, and let's you see what is stored in the Router's
NVRAM (Non-Volatile Memory), the place where configurations live when the power is off.

The other one is SHOW RUNNING-CONFIG, which shows you the configuration
as you have changed it since turning on the router.

For Security Reasons, these commands are not available from the User Prompt.

Try to do a SHOW RUN or SHOW START from the Router> prompt,
and it'll give you a very nasty error message.

The reason for this is that most of the Passwords are shown by these commands.

Needless to say, this would be Very BAD!

Get into Privileged Exec Mode (Enable Mode)

Router> (type in enable)

Password: (type in your enable password.)
(if you have set up an Enable Secret password, you have to use that instead)

Router# (type in show startup-config)

Router#show startup-config %% Non-volatile configuration memory is not present
Router#show running-config
Building configuration...

Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router
!
enable secret 5 $1$60Ad$4etO0u.sxYl6DHv1pEXJ4/
enable password CISCO
!
ip subnet-zero
!
!
!
!
interface Ethernet0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial0
no ip address
no ip directed-broadcast
no ip mroute-cache
shutdown
no fair-queue
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
!
interface Serial2
no ip address
no ip directed-broadcast
shutdown
!
interface Serial3
no ip address
no ip directed-broadcast
shutdown
!
interface BRI0
no ip address
no ip directed-broadcast
shutdown
!
ip classless
no ip http server
!
!
!
line con 0
password CISCO
login
transport input none
line aux 0
password CISCO
login
line vty 0 4
password CISCO
login
!
end

Show Running-Config

As we said a minute ago, SHOW RUNNING-CONFIG, let's you see the configuration
that is actually Live, in RAM Memory, running right now on your router.

Since we really haven't changed the configurations much recently,
let's rename the Router to something different using the HOSTNAME command.

Router# (type in hostname ZEUS)

You should now see the following Prompt, because Router is now ZEUS.

ZEUS#

Now if we type in the SHOW RUNNING-CONFIG (or SHOW RUN for short)
you will see that the name of the router is now ZEUS.

ZEUS# (type in show run)

Router(config)#hostname ZEUS
ZEUS(config)#exit
ZEUS#
1d03h: %SYS-5-CONFIG_I: Configured from console by console
ZEUS#show run
Building configuration...

Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname ZEUS
!
enable secret 5 $1$60Ad$4etO0u.sxYl6DHv1pEXJ4/
enable password CISCO
!
ip subnet-zero
!
!
!
!
interface Ethernet0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial0
no ip address
no ip directed-broadcast
no ip mroute-cache
shutdown
no fair-queue
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
!
interface Serial2
no ip address
no ip directed-broadcast
shutdown
!
interface Serial3
no ip address
no ip directed-broadcast
shutdown
!
interface BRI0
no ip address
no ip directed-broadcast
shutdown
!
ip classless
no ip http server
!
!
!
line con 0
password CISCO
login
transport input none
line aux 0
password CISCO
login
line vty 0 4
password CISCO
login
!
end

ZEUS#


8 - Commands To Save Configurations

Your basic command to save the Running Configuration is very simple.

Remember that the Router saves it's configurations in the NVRAM,
(Non-Volatile Random Access Memory)
and also remember that the saved in NVRAM config is called the "Startup Configuration".

So what we are going to do is to make a Copy of the Running-configuration,
and save it in the Startup-Configuration.

The command we will use is copy running-configuration startup-configuration,
or as it is normally abbreviated, "copy run start"

ZEUS# (type in copy run start)

ZEUS# copy run start
Destination file [startup-config]: (here you would press Return)
Building Configuration...

ZEUS#

If you have an older Router, the old command is WRITE MEM.
You'll still see people using this from time to time, so remember it!
Cisco says that this command will not be available in newer models.

If we were on a Network, and had what's called a TFTP server,
(which is shorthand for Trivial File Transfer Protocol)
then we could use a COPY command to send the configuration to a file
that would be stored until we need it on the TFTP server.

The command to use for this is COPY RUN TFTP

And then the Router asks for the IP address of the TFTP server.
Remote host[]? 10.1.1.1 (this is just a madeup sample IP address)

Name of configuration file to write [ZEUS-confg] Return
(the above writes the configuration to the file ZEUS-confg)

Write file ZEUS-confg on host 10.1.1.1? Return
[confirm] Return

Building configuration...

And that, as they say, is all there is to that.

Once again, since for this tutorial we only have one router and no network,
we won't be able to practise doing a COPY RUN TFTP for real.
But hopefully you've got the basic concept, right?

Now we go on to the obvious next step, and learn to put the saved file back in.



9 - Commands to Reload Configurations

As you may have already guessed, the command to put the Saved Configuration
back into the Running Configuration is simple.

The command to do this is RELOAD.

ZEUS# (type in reload)

That's it, easy, simple. Be thankful!

Next we'll learn how to reload from a TFTP server.

The command for doing this is COPY RUN TFTP.
(which just says, copy to the Running-config from a TFTP file)

Remote host[]? 10.1.1.1
Name of configuration file to write [ZEUS-confg]? return
Write file ZEUS-confg on host 10.1.1.1?
[confirm] return

Building configuration . . .

OK

And now you know two methods for re-doing the router's running configuration.

Why would you want to do this?

Well, it is good for resetting the router back to square one if you make a mistake.

It is also good for doing a practise Lab a second time.

Which brings us back to the Nuclear Weapon of configuration commands:

ERASE STARTUP-CONFIG takes your Router and Nukes it back to the stone age.
In other words, it erases your NVRAM so that the next time you RELOAD,
you have a completely blank Router.

We will be using this command in the next section.
As mentioned back at the very beginning, do NOT use this on a production router.
This will in fact bring down your Network and have you looking through want ads.


10 - Using the Setup Command

If you wish to use the lazy man's method of setting up your Router,
Cisco has provided a set of Questions and Answers for you.

A brand-new Router should enter automatically into what is called
the "System Configuration Dialog" or "the Setup Dialog".

If you have already got a configuration and want to use "Setup",
simply get into Enable mode and issue the Command SETUP

You will start to see a number of questions,
most of which have a suggested Default answer in [Brackets].
For those answers you find agreeable, simply Press the "Enter" key

If you want to change something you can type in your own answers.

Here is what the "System Configuration Dialog" looks like:

- - - System Configuration Dialog - - -
At any point you may enter a Question Mark "?" for Help.

Refer to the "Getting Started" Guide for additional Help.

Use Control-c to Abort the Configuration Dialog at any Prompt.

Default settings are in square brackets []

Would you like to enter the initial configuration dialog? [yes]
(this is where you press the "Enter" key for [yes]

First, would you like to see the current Interface summary? [yes]

Pressing Enter at this question gives you a Summary
of what Interfaces your Router has configured.
If it is a New Router straight from the Router Factory,
there won't be a whole lot going on.
That's because it's not configured yet, right?

Anyway, a typical Interface Summary from an unconfigured Router looks like:

Interface ... IP Address ... OK? .. Method ... Status ... Protocol
----------------------------------------------
Ethernet0.... unassigned ... NO ... not set .... down ... down
Serial0 ........ unassigned ... NO ... not set .... down ... down
Serial1 ........ unassigned ... NO ... not set .... down ... down

Anyhow, as you can see, these Interfaces are not doing anything much.
They have no IP Addresses (all unassigned!) and they are Not "OK?"
What's worse, they have no method as it's "not set",
and their status is "down" and protocol is "down".
How very depressing!

Of course that brings to mind the important question,

"What is an Interface?"

An interface is something you connect things to,
such as putting a power cord into an electrical socket.
You could think of Interfaces as the places you plug cables
into on the back of your Router.

For example, the Ethernet Interface is where the Ethernet cable goes,
and the Serial Interface is where you plug in the Serial Cables
(add milk and sugar to taste).

But the Interface is also made up of Hardware (chips and boards)
as well as the Software that makes the hardware work.

Got that picture? Good... we'll wait til later to tell you about "Virtual Interfaces"!

Global Configuration

But wait, there's More!

The System Configuration Dialog has only just begun!

The next Step will allow you to give your Router a Name
Let's name this Router after the ancient Sumerian City "UR".
Type in the Name "URouter" in the text box below.

Enter Host Name [Router]

The screen on your Terminal should now look like this:

Configuring Global Parameters: Enter Host name [Router] : URouter

Which will change the Prompt on your Terminal Screen to change to:

URouter#

Note that the Router now has Your Name on it, "URouter"!

The next step is to choose Passwords to protect your Router
There are two "Command Levels" in the Cisco IOS

  • "Non-privileged" for the Ordinary User (who can't do much)

  • "Privileged" for the God-like SuperUser (see the Comic Book!)

The "Non-privileged" can log onto the Router with the regular password
and they can basically look at stuff but can't touch.

Enter Password: (type in your password here)

The "Privileged" Superuser gets to type in a Special Password,
Which Cisco decided to call the "Enable Password. (for Enable mode?)

Of course the "Enable" password is plain old text and not secure,
So Cisco recommends that you use the encrypted "Enable Secret" password instead.

Enter Enable Password:
Enter Enable Secret Password
Go ahead and put in passwords for both just for practise
(Remember your Passwords, but Do Not stick them on your Monitor!)

Protocols

This next section of the Systems Configuration Dialog is for Protocols.

Protocols are simply things we agree upon for communicating stuff.
Like when the Phone rings, you pick it up and say "Hello".
That is part of a Protocol.
Then the person who called you says "Hello" and you start talking.

Anyway, please configure the following Protocols:

First you will be configuring the Router to use the
Simple Network Management Protocol.
(which is anything but simple but does help Manage Networks)

Configure SNMP Network Management? [yes]: (press return)
Community String [Public]: (press return again)

Now you get asked if you want to use the OSI Connectionless Network Service.
(trust us, you do not need this protocol right now)

Configure CLNS? [NO]: (just say No to CLNS!)

Next we pretend you are a Mac fanatic with a huge Multi-Zone Network!

Configure AppleTalk? [no]: (write in "no" here or press RETURN)

Configure IPX? [no]: (write in "no" here or press RETURN)

You can also safely say "NO" to Banyan Vines, Xerox XNS, and Digital' DECnet.
They are still being used out there somewhere... but not by you, not today!

Configure Vines? [no]:
Configure XNS? [no]:
Configure DECnet? [no]:

The next Question asks if you want to configure Bridging.
Now this is only Transparent Bridging, which you don't need right now,
so go ahead and say "No".

Configure Bridging? [no]:
(write in "no" here or press RETURN)

Now we get into the main Protocol for the whole Internet,
which of course is named the "Internet Protocol" or "IP" for short.

Configure IP? [yes]: (say Yes to IP please!)

Now it asks if you to want to use the Interior Gateway Routing Protocol
This Protocol does IP Routing for you, but you don't want it Now, okay?
Configure IGRP? [yes]: (write in "No" please)

You don't want the Apollo Routing Protocol either, unless you're on the Moon?

Configure Apollo? [no]: (nope - don't want this...)

Interface Configuration

Well, that's enough for the Global Configuration stuff for now.
We'll be moving on to the even more complicated Interface junk.

If you remember, an Interface is something that you plug into.
Without these there is no connection to anything
and you just spent a couple thousand dollars on a Router for nothing.

You will notice that most of your Configurations
you'll be doing start out with Global Configuration commands
And then go on to do some Interface Configuration commands
Personally I think this is a plot by evil Space Aliens...

So you thought you were almost finished, eh?

Systems Configuration Dialog - Part 2

Revenge of the Interfaces!

Okay, what you will actually see next in the Dialog is:

Configuring Interface Parameters:
Configuring Interface Ethernet0:

Cisco Routers come with a number of different Interfaces.
One of them is, of course, the one marked Console that you attached your computer to.

The one mentioned above, Ethernet0, is your Interface
that goes to your Ethernet "Local Area Network".

Is this Interface in use? [no] (write in "Yes")
Saying "Yes" turns on the Ethernet0 Interface. This is a good thing!
Configure IP Address on this Interface? [no}
Answer "Yes" or you won't get very far on the network.

Now you need to pick out an IP Address!
This is my favorite part in all the Computer textbooks,
You know, the part where they tell you to ask your System Administrator
what numbers you should put in for an IP Address...
which is fine as long as YOU are not the Sys Admin, right?

Well, since we are setting this up for a home-use test laboratory,
we can use one of the 3 Networks assigned for "Private" use
to steal our Internet Protocol (IP) Addresses from.

Let's pick the Class A address, "10.0.0.1" to use, cause it's easy.

Put it in when the Systems Configuration Dialog asks you:
IP Address for this Interface: Put in "10.0.0.1" here.

 

IP Addresses, Subnet Masks, & Cisco Confusions!

Then it will ask for the Number of Bits in the Subnet "Field",
which basically tells the Router which part of the 10.0.0.1 is the Subnet Part.

Warning! This is going to get a Bit confusing! (yes, Pun intended, sorry)

Since this is a Classful Class A address the default is 8 bits.
So the Subnet Mask looks like 1111 1111 . 0000 0000 . 0000 0000 . 0000 0000
(I put space between each set of 4 numbers cause it's easier to read)
Which for reasons of convenience is written in Decimal as 255.0.0.0

It is actually a lot easier to see What is really going on in Binary Bits,
since anything that is a One gets counted as a Network address,
and anything that is a Zero is just a humble Host address for a lowly computer.

Of course Cisco doesn't count the Class A Network bits,
so the correct "Bits in Subnet Field" they want is "Zero". (0)

Basically Cisco doesn't usually count Subnet Mask bits
unless they are above and beyond the call of Classful IP addressing.
Even when it'd be simpler just to look at the number of 1's and go,
"Hey, there's 8 ones in that Subnet Mask!"

We'll have to go over all this IP addressing stuff later over a good Root beer...

Number of Bits in Subnet Field?: (try "0")

The Router now spits out the following Interesting Info:
Class A Network is 10.0.0.0, 0 Subnet Bits; Mask is 255.0.0.0

I suppose right now you are breathing a sigh of relief,
expecting that the worst is over and it's all downhill sailing from here.

Well, in this case you are correct, since we are not going to try IPX/SPX,
Appletalk, Banyan Vines, Decnet, or any of the other interested protocols yet.

Actually using SETUP is the easy way to get a Router up and running,
but as we mentioned earlier, doing things the easy way means
that you don't have to learn as much.

And for the Cisco tests, you had better take the time to learn everything!

Summary

In the course of this Tutorial:

  1. You will have taken your Router out of its box.

  2. Plugged it in and turned it on.

  3. Learned about the important parts of a router.

  4. Logged onto the router and protected it with Passwords.

  5. Navigated through the IOS Shell, done editing and commands.

  6. Discovered the Secrets of using Context Sensitive Help or a "?".

  7. Used SHOW commands to look at your router's elements.

  8. Done SHOW RUN and SHOW START to look at the configurations.

  9. Saved your Configurations to NVRAM.

  10. Performed a RELOAD, to reload configurations from the Startup Config.

  11. Learned to use the SETUP command to do configure a router.

    This should be enough for you to be able to get a router up and running.
    You, of course, know that is merely the beginning.

    The true challenge come when you have two or three, or 30,000 routers,
    all interconnected, and each one of them serving one or more networks.

    Hopefully you will look forward to each challenge as it comes.
    Learn the Basics well, and they will serve you well in the future!

Questions on the Basic IOS Commands

Router Parts

1. Which of the Below is a form of Permanent Memory used to store
a very basic form of the Cisco IOS software, the POST, and Bootstrap program?

  1. Flash Memory

  2. ROM- Read Only Memory

  3. NVRAM - Non-Volatile RAM

  4. RAM - Random Access Memory

2. Which kind of Memory is the full Operating System or "Image" stored in?

  1. RAM - Random Access Memory

  2. NVRAM - Non-Volatile RAM

  3. Interfaces

  4. Flash - Electronically Erasable and Re-Programmable Memory.

3. What is the regular working memory of the Router?

  1. Flash

  2. NVRAM

  3. RAM

  4. ROM

4. Which are the "Ports" that connect your Router to the outside world?

  1. NVRAM

  2. Interfaces

  3. Flash

  4. LEDs

Booting Up Questions

5. What is the very first thing that happens when your Router Boots U