Cisco router sets IOS mutual upgrade

The Cisco router sets IOS to upgrade each other. My company's network department has a Cisco router 2501, but IOS is bad. Here I call it cisocB, and another 2501 router IOS is good, we prefer ciscoA. Good IOS is no longer available on my PC, but it is transferred to the PC through TFTP on the PC, it would be a waste of time to upload it to the bad one ,. Then I thought of a way to directly configure the vro as a TFTP server.
My connection method is that the two routers are connected through the E0 port. First, on the good router (cisocA), I configure the E0 port as 192.168.10.90 (the IP address is randomly configured, as long as the two E0 ports can PING each other) and then enter the tftp-server c2500-js-l.122-7a.bin under the configuration mode (this is the IOS file name in your IOS, use show version to check your IOS file name. After this A has been configured, configure it on "B". First, enable this to BOOT to the BOOT mode, in global configuration mode, enter config-register 0x2101 and then restart the vro. After starting to BOOT mode, configure your E port. After the BOOT mode is enabled, enter copy tftp flash, prompt you enter the TFTP server, and then enter the file name, you can, the specific steps are as follows: cisocA # conf tcisocA (config) # tftp-server c2500-js-l.122- 7a. bincisocA (config) # int e0cisocA (config-if) # ip add 192.168.10.90 255.255.255.0cisocA (config-if) # no shut www.2cto.com ciscoB (config) # conf tciscoB (config) # config-register 0x2101ciscoB (config) # endciscoB # reloadSystem configuration has been modified. save? [Yes/no]: yciscoB (boot)> enableciscoB (boot) # conf terminalciscoB (boot) (config) # int e0ciscoB (boot) (config-if) # ip add 192.168.10.80 255.255.255.0ciscoB (boot) (config-if) # no shutciscoB (boot) (config-if) # endciscoB (boot) # erase flashSystem flash directory: file Length Name/status1 15533612 c2500-js-l.122-7a.bin [15533676 bytes used, 1243540 available, 16777216 total] Erase flash device? [Confirm] www.2cto.com Are you sure? [Yes/no]: yAddress or name of remote host [192.168.10.80]? 192.168.10.90Source file name? The c2500-js-l.122-7a.binDestination file name [c2500-js-l.122-7a.bin]? Erase flash device before writing? [Confirm] (Press ENTER) Copy 'c2500-js-l.122-7a.bin 'from serveras 'c2500-js-l.122-7a.bin' into Flash WITH erase? [Yes/no] After y is input, the program automatically copies IOS. After successful, you can configure ciscoB (config) # config-register 0x2102ciscoB (config) as follows) # The reload step is complete. This article comes from the fat shark network.