The Cisco IOS Software Filenaming Convention

Cisco uses a standard convention to name all Cisco IOS Software image files, as shown in Figure A-3. Sometimes you might have an image filename (either in Flash memory or on a TFTP server) and need to determine exactly what platform, feature sets, and Cisco IOS Software release it supports.

Figure A-3. Cisco IOS Software Image Filename Format

The first group of characters , PPPPP, designates the image's hardware platform. The second group of characters, FFFF, forms a string in which each character (or a character and a number) specifies a feature set included in the image. Two characters, MM, describe the image format. The first character specifies the type of router memory where the image is executed. The second character tells how the image is compressed. The final group of characters, VVVV, specifies the Cisco IOS Software release number. The image filename can also have a suffix, such as .bin or .tar.

TIP

If you are trying to determine whether you can safely remove a Flash card from a router, look at the first M character in the Cisco IOS Software image filename. The execution area character is f if the image is executed directly from Flash. In this case, the router requires Flash to be installed so that the Cisco IOS Software image can be run. If the character is m, the router has already read the image from Flash, decompressed it, and is running it from RAM. After the router has booted , the Flash can be safely removed.

To see what Cisco IOS Software image your router is running, use the show version or show flash command. The image filename is displayed, as demonstrated in Example A-1.

Example A-1 Checking to See Which Cisco IOS Software Image Is Currently Running

 Router#  show flash  -#- ED --type-- --crc--- -seek-- nlen -length- -----date/time------ name  1   .. image    F2859862  FE7F74   22 16547572 May 30 2001 02:39:27 rsp-jo3sv-mz   .122-1.bin  4030604 bytes available (16547700 bytes used) Router# UKHospH28D1b#show ver Cisco Internetwork Operating System Software IOS (tm) RSP Software (RSP-JO3SV-M), Version 12.2(1), RELEASE SOFTWARE (fc2) Copyright  1986-2001 by cisco Systems, Inc. Compiled Fri 27-Apr-01 03:19 by cmong Image text-base: 0x60010968, data-base: 0x6196E000 ROM: System Bootstrap, Version 11.1(8)CA1, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1) BOOTFLASH: GS Software (RSP-BOOT-M), Version 11.1(29)CC1, EARLY DEPLOYMENT RELEA SE SOFTWARE (fc1) UKHospH28D1b uptime is 11 weeks, 1 day, 1 hour, 12 minutes System returned to ROM by reload at 14:43:04 UTC Tue May 29 2001  System image file is "slot0:rsp-jo3sv-mz.122-1.bin"  ... 

Here, rsp-jo3sv-mz.122-1.bin indicates that rsp is the hardware platform (Cisco 7500 series). The jo3sv indicates enterprise (j), firewall/IDS (o3), IP Plus with NAT/VoIP (s), and Versatile Interface Processor (VIP) support (v). The mz suffix indicates that the image runs in router RAM memory and is zip-compressed. The 122-1 indicates that the image is Cisco IOS Software version 12(2)1, or the first maintenance release of major release 12(2).