Traditionally installing and uploading images on Cisco router has been done with TFTP. As the IOS images have grown larger and larger some TFTP servers have problems with supporting these large file sizes. Secure Copy - scp can be used in place of TFTP to interact with the IOS file system. This eliminates many of the problems related to TFTP with the added benefit of security. Below is an IOS config snippet for making this work:
! AAA authentication and authorization must be configured properly for SCP to work.
aaa authentication login default local
aaa authorization exec default local
! Set your login credentials as appropriate
username user privilege 15 password 0 securepass
! SSH must be configured and functioning properly.
ip ssh time-out 120
ip ssh authentication-retries 3
ip scp server enable
At this point you can use any scp client to interact with the IOS filesystem. So for example on a Unix-like filesystem:
scp -2 ./c2800nm-adventerprisek9-mz.151-2.T1.bin \
The above will copy the image to the flash filesystem on router 10.1.1.1. The -2 option forces SCP to use version #2