Cisco Internetwork Operating System

Cisco Internetwork Operating System

Cisco IOS

 

·         Cisco Internetwork Operating System - provides a command-line interface (CLI) which allows network operators to check the status of the router and network administrators to manage and configure the router.

 

Command Executive or EXEC

 

·         The software that interprets the commands

 

TFTP

 

·         Trivial File Transfer Protocol server - the router can obtain configuration information from this. You can store the router configuration information as a file on a TFTP server and download it to configure the router.

 

User EXEC Mode

 

·         When the prompt displayed is router1>
Network operators can check router status and review several of the router settings but you cannot configure the router in this mode.

 

Privileged EXEC Mode (enable mode)

 

·         To enter privileged EXEC, you can type the 'enable' command at the user mode prompt.
Greater than symbol (>) changes to a pound sign (#)
YOU CAN CONFIGURE ROUTER HERE

 

Global Configuration Mode

 

·         Command: 'configure terminal' while in enable mode (privileged EXEC mode) Allows you to configure various items, including clock, host name, enable password, and enable secret password.

 

Interface Configuration Mode

 

·         allows you to configure the Ethernet, serial interfaces on your router and settings such as, IP for a specific interface.

 

Interface Configuration Mode

 

·         allows you to configure the Ethernet, serial interfaces on your router and settings such as, IP for a specific interface.

 

Line Passwords

·         Are the first line of defense against unauthorized intrusion into the router. You can set passwords for each line used to configure the router.

 

ROM

 

·         Read Only Memory - loads the bootstrap program that initializes the router's basic hardware components. ROM is not modified during normal operations, but i can be upgraded with special plug-in chips. The content of ROM is maintained even when the router is rebooted.

The ROM monitor firmware runs when the router is turned on or rebooted. You can configure new passwords with ROM monitor if password recovery is necessary. You can also download new software to the router using ROM monitor. You know that you are in ROM monitor mode when the prompt is, > or rommon 1>

 

 

Flash Memory

 

·         A type of erasable, programmable, read-only memory (EPROM). This means that flash memory is not typically modified during normal operations; however, it can be upgraded or erased when necessary. Content of flash memory is maintained even when the router is rebooted.

Contains the working copy of the current Cisco IOS and is the component that initializes the IOS for normal router operations. Flash memory on certain series of Cisco routers can store multiple versions of the IOS, which can make upgrading the IOS easier and safer.

 

NVRAM

 

·         Nonvolatile Random Access Memory- is a special type of RAM that is not cleared when the router is rebooted. The start up configuration for the router is stored in NVRAM by default.

 

RAM/DRAM

 

·         Random Access Memory - also known as Dynamic Random Access Memory (DRAM) is a volatile hardware component because its information is not maintained in the event of a router reboot. The router's running (working) configuration file is maintained in RAM/DRAM