Internetwork Operating System IOS

Router Theoretical Image 

IOS is Cisco's internetwork operating system. Just as PCs have operating systems and LANs have network operating systems, it is Cisco's belief that internetwork need their own operating systems. Cisco's goal was to create an operating system that could evolve as the network evolved.Cisco IOS is a multitasking operating system that is integrated with routing, switching, internetworking, and telecommunications functions.

It is a CLOSED SOURCE model that works only on CISCO devices. It's a command line interface hence can be  difficult to those who love to work on gui.though i personally never had any problem in working as the commands are easy to remember and execute. the Current version of IOS is 15.2(4)M2

Now as the IOS is present on the devices ,they can be as accessed by connecting a terminal or PC to a console port on a networking device. A terminal emulation package or Telnet is used to access the IOS software.

NAMING CONVENTION OF IOS FILES

Whenever " show flash " command is executed on privilege Mode you will find something like this
c2600-ik9s-mz.121-3.T.bin

• c2600 --- denotes the CISCO hardware
• ik9s-- feature supported
• m- indicates the memory location
• z-- show the compression technique used
• 121--Maintenance release
• 3-- individual release
• T-- train Identifier

DIFFERENT TYPES OF FLASH MEMORY LOCATIONS
   

Code	Location
F	IN FLASH
M	IN RAM
R	IN ROM
L	LOCATED AT RUN TIME

DIFFERENT TYPES OF COMPRESSION

CODE	COMPRESSION
Z	IN ZIP
X	IN MZIP
W	IN STAC COMPRESSION

All the information left, will be discussed in detail in the future Blogs..
Till then bye

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