Cisco IOS Modes of Operation

Commands can be executed in Cisco IOS software under access modes: User and Privileged. The commands in the User mode is in a way, a low level access version of the Privileged mode.

The below table explains the different modes, what can be done in these modes and the prompt telling you which mode you are in.


User mode: You enter this mode when you start a router. You can see ‘Router>’ prompt. Command like ‘ping, telnet, and rlogin’ run in this mode, also you can get information regarding the IOS if you type ‘show version’. So this mode gives you information but does not let you make any modification in the configuration. For any configuration or modification of the router you have to enter into the privileged mode by giving the command ‘enable’

Privileged mode: You will be prompted to enter a password in order to access this mode (while configuring a router for the first time, the password for the privileged mode can be avoided but that’s a security risk). You can modify the router configuration, the interfaces on the router or create an initial configuration following the sub-modes.

In order to make things easier, the sub modes can be identified from the prompt. For example, the privileged mode shows ‘router#’ and if you enter the command ‘configure terminal’ here, the prompt changes to ‘router (config) #’, so this tells you that you are in the ‘Global Configuration Mode’

A list of every command that run in each mode can be displayed by entering ‘?’ while in that particular mode, so this makes things a lot easier. Also you don’t have to type every command, you just have to type the first few letters and let the IOS auto-complete it.
Example: Instead of typing ‘Router#configure terminal’ you can type ‘Router#conf ter’

There are a few Hot Keys that will help you work faster while working on Cisco IOS,

CTRL A	Moves cursor to the beginning of the line
CTRL E	Moves cursor to the end of the line
CTRL B	Moves cursor back one character
CTRL F	Moves cursor forward one character
ESC B	Moves cursor back one word
ESC F	Moves cursor forward one word
CTRL D	Delete one character
Backspace	Delete one character to the left of cursor
CTRL R	Redisplays a line
CTRL V	Erases a line
CTRL W	Erases a word
Ctrl Z	Exits configuration mode
TAB	auto completes partially entered word

Connecting the Cisco IP phone 7940G

The inbuilt Cisco two-port Ethernet switch allows for a direct connection of the IP phone to a 10/100BASE-T Ethernet network via an RJ-45 interface. A single LAN connection will be enough for both the phone and a nearby PC.

The system administrator can designate separate virtual LANs (VLANs) for the PC and Cisco IP Phones providing improved security and reliability of voice and data traffic.

The Cisco IP Phone 7940G can also receive power down the LAN from any of the Cisco inline power-capable blades and boxes

Network Requirements
.The network must have a working VOIP network, which means Voice over IP (VoIP) configured on your Cisco routers and gateways
. Cisco CallManager* Release 3.0 or higher installed in your network and configured to handle call processing
. IP network that supports DHCP or manual assignment of IP address, gateway, and subnet mask

Adding a Cisco IP Phone Using Cisco CallManager
The IP phone has to be added to the CallManager before we can actually use it. This is done with Cisco CallManager Administration using either auto-registration or without auto-registration.

Auto-registration allows you to automatically add Cisco IP Phones to Cisco CallManager Administration simply by plugging them into a Cisco CallManager network. Auto-registration automatically assigns a directory number (selected from a range of numbers) to the telephone.

By default, auto-registration is turned off. When Cisco CallManager Administration is configured, you can turn on auto-registration by specifying a range of numbers from which auto-registration can choose directory numbers. Then, when new phones are added, they are automatically assigned the next available directory number. If a phone is moved to a new location, its phone number does not change.

Turning on Auto-Registration:
.Open Cisco CallManager Administration.
.Click Configuration.
.In the Auto-Registration area, click Configure. Type the start and end directory numbers (provided by the telephone company).
.Click Update. (The range of directory numbers auto-registration can use is configured, and auto-registration is enabled. When a new phone is added to the system, its directory number is automatically assigned by auto-registration).

Turning auto-registration off prevents unauthorized devices from registering with and gaining access to the Cisco CallManager.

Turning off Auto-Registration:
.Open Cisco CallManager Administration.
.Click Configuration.
. In the Auto-Registration area, click Configure. ( Type the same directory number in both the start number and end number boxes. For example, type 1000 as the start number, and 1000 as the end number).
.Click Update.( Auto-registration is turned off. New phones added to the system must be manually configured in Cisco CallManager Administration).


*Cisco CallManager: A software that runs on a Windows 2000 server and sets up and tears down calls between phones, integrating traditional PBX functionality with IP network. Cisco CallManager manages the components of the IP telephony system—the phones, access gateways, and the resources necessary for such features as call conferencing and route planning.

(More on CallManager some other time…)