Cisco IOS software, just like other operating systems, provides a platform to use routers and other Cisco devices. In other words, Cisco IOS is the operating system of Cisco routers. Cisco offers IOS software as a single image file. Routers use flash memory to store the IOS image file.
When a Cisco router is powered up, it copies the IOS image file from the flash memory to the RAM. After copying, if the IOS image file is compressed, the router extracts it. In the running state, the router uses the IOS software from the RAM. When the router is powered off, all contents of the RAM (including the running IOS software) are deleted. The same process is repeated each time when the router is used.
If a router, upon power-on, does not find a valid IOS image file, it starts in an emergency mode. This mode is known as the ROMMON mode. The ROMMON mode allows us to install a new IOS image file from the file server.
First, you have to use the show flash or dir flash: to view (get your IOS image file and use these commands).
TestASA# show flash
–#– –length– —–date/time—— path
10 2048 Nov 14 2015 08:30:18 log
17 2048 Jun 10 2013 07:50:08 crypto_archive
18 2048 Jun 10 2013 07:50:32 coredumpinfo
19 59 Jun 10 2013 07:50:32 coredumpinfo/coredump.cfg
99 25025404 Nov 26 2015 12:49:26 asdm-751.bin
100 27187200 Nov 26 2015 12:47:36 asa916-8-k8.bin
or
TestASA# dir flash:
Directory of disk0:/
10 drwx 2048 08:30:18 Nov 14 2015 log
17 drwx 2048 07:50:08 Jun 10 2013 crypto_archive
18 drwx 2048 07:50:32 Jun 10 2013 coredumpinfo
99 -rwx 25025404 12:49:26 Nov 26 2015 asdm-751.bin
Method One:
TestASA# copy flash:asdm-751.bin tftp
Source filename [asdm-751.bin]?
Address or name of remote host []? 192.168.177.17
Destination filename [asdm-751.bin]?
Writing file tftp://192.168.177.17/asdm-751.bin…
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Method two
TestASA# copy flash tftp:
Source filename []?
Address or name of remote host []?
————-here you have to specify the source filename and
the tftp name or IP Address as well.
Just follow the prompt.