Cisco Router Modes
Introduction
From my
personal experience, I have noticed that the lower end
routers (600-1400) use different commands than the mid
to upper range routers (1600 and above). The commands we
are going to talk about here cover most aspects of the
1600, 1700, 2500, 2600, 3600 series. Most are the same,
but there are always a few variations to these commands
depending on the interfaces your router has,
IOS version, and the type
of WAN protocols they support.
Because
there is such a wide range of interfaces on a router and
also alot of different versions of the
Cisco
IOS, I decided to stick to an example where our
router is running IOS
version 12 and has one IDSN S/T
(without NT terminator) interface and one
Ethernet interface. That's
a total of 2 interfaces. I understand that this is quite
a specific example, but it would take an enourmous
amount of time and effort to cover all cases.
Now, when
you power up a Cisco
router, it will first run a POST test to ensure all
hardware is ok, and then look into the
Flash to load the
IOS. Once the
IOS is loaded, it will then
check the NVRAM for any
configuration file. Since this is a new router, it won't
find any, so the router will go into "setup
mode".
Setup Mode
The setup
mode is a step-by-step process which helps you configure
basic aspects of the router. When using this setup mode,
you actually have 2 options:
1)
Basic Managment Setup,
which configures only enough connectivity for managment
to the system.
2)
Extended Setup, which
allows you to configure some global parameters and
interfaces.
It should
be noted that when you are prompted to enter a value at
the console prompt, whatever is between the square
brackets [ ] is considered to be a default value. In
other words, if you hit enter without entering anything,
the value in those brackets will be set for the specific
question.
I'll try to
keep this as simple and straightforward as possible.
Cisco routers have
different configuration modes (depending on the router
model), and by this I mean there are different modes in
which different aspects of the router can be configured.
These are :
1)
User Exec Mode
( >)
- Click to
select
2)
Privileged Mode
(#) which has
as a subset, the Global
Configuration mode -
Click to
select
To be able
to get into either User Exec
or Privileged mode,
you will most likely need a password. This password is
set during the initial configuration of the router or
later on. Once in Privileged Mode,
you can then enter Global
Configuration Mode (password not needed to enter
this mode) to then futher configure interfaces, routing
protocols, access lists and more.
The picture
below shows you a quick view of the modes. Notice the
red arrow, it's pointing towards the
Global Configuration Mode
and Privileged
mode meaning
that some of the specific configuration modes can be
entered from Global
Configuration Mode and
other from Privileged
mode:
I have
given each mode its own separate page to avoid squezing
all the information into one huge page. This makes it
easier for you to read.
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