Cisco IOS Images Naming Convention
The file name will look like c2600-i-mz.122-28.bin. Cisco follows a particular naming convention. The name of IOS image contains more information about the router. The IOS file name can be compared with cXXXX-yyy-mz-123-2.1a.T1.bin.
IOS stands for Internetwork operating System. IOS is used in Cisco routers and switches and IOS proprietary Operating System of the Cisco devices. IOS includes all the necessary configuration files for routers and switches to perform the operations like routing, providing security etc. IOS is stored in Flash and on boot up, IOS is transferred to Random Access Memory.
IOS was first developed for only routers, later it was also developed for switches. IOS became more popular because of its features like connectivity, reliability, Scalability, Security etc. IOS can support more protocols than any other Operating systems available in the market.
IOS of any version looks same at the first instance. To which file name of IOS image that is running on your router or switch, we have to enter command line interface of the router. Enter into Privileged EXEC mode prompted by ‘#’ and enter the command show version
CISCO-ROUTER# show version
CISCO-ROUTER represent hostname of the router, ‘#’ indicates that we are in privileged EXEC mode
The alternative way to know the IOS version present in router is
CISCO-ROUTER# show flash
These two commands help us to know the file name of IOS image that is running on the Cisco device.
The file name will look like c2600-i-mz.122-28.bin. Cisco follows a particular naming convention. The name of IOS image contains more information about the router.
The IOS file name can be compared with cXXXX-yyy-mz-123-2.1a.T1.bin. cXXXX indicates the platform on which IOS is running. Yyy is the feature set, m points to the memory location where IOS is stored. Z indicates the compression method used, 123 says the train number of IOS version, 2 represents maintenance release of IOS version.
1 informs about interim Build Number and letter ‘a’ is the Rebuild letter. T is used to identify the train of IOS image and 1 is rebuilding number. ’.bin ‘is the extension of the file and is indicates that the file is a binary file.
Certain useful codes in naming convention are:
Memory location codes:
F in the memory location indicates the image is running from flash. Similarly, ‘m’ indicates running from RAM, ‘r’ when running from ROM and ‘I’ if the image can be relocatable while running.
Z indicates compression in ZIP format. Whereas ‘X’ indicate that mzip compression is used
Feature set codes:
‘i’ in feature set indicates IP, ‘I’ indicates IPX, ‘b’ if apple talk is being used. ‘o’ for firewall, ‘v’ indicates voice.
In the above example c2600-i-mz.122-28.bin, c2600 is the platform on which IOS is running. ‘i’ points to IP routing, ‘m’ says that IOS is running from RAM and ‘z’ indicates compression technique and 122-28 gives the information that IOS version is 12.2 and patch 28.
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- Cisco IOS Modes, user Exec, Privileged, Global Configuration, Setup and ROM Monitor Mode