We have accidently deleted cisco 1861 IOS from the flash. We have a backup copy of IOS. We tried to upload IOS file from the PC which is running tftp software, but it didn't work. Could someone help us explain how to upload the IOS on 1861 router using tftpdnld on 1861 router? Please also explain the network connection and settings on the 1861 router and the PC. Thanks.