31 Days Before Your CCNA Exam

Day 15 187The pertinent command for recovering an IOS image is tftpdnld for TFTP download. To enablethe router to use the tftpdnld command, first you must set specific ROMmon variables. Thesevariables, shown in Example 15-9, are syntax- and case-sensitive.Example 15-9Using tftpdnld to Recover an IOS Imagerommon 2 > IP_ADDRESS=192.168.20.1rommon 3 > IP_SUBNET_MASK=255.255.255.0rommon 4 > DEFAULT_GATEWAY=192.168.20.254rommon 5 > TFTP_SERVER=192.168.20.254rommon 6 > TFTP_FILE=c1841-ipbase-mz.123-14.T7.binrommon 7 > tftpdnldIP_ADDRESS: 192.168.20.1IP_SUBNET_MASK: 255.255.255.0DEFAULT_GATEWAY: 192.168.20.254TFTP_SERVER: 192.168.20.254TFTP_FILE: c1841-ipbase-mz.123-14.T7.binInvoke this command for disaster recovery only.WARNING: all existing data in all partitions on flash will be lost!Do you wish to continue? y/n: [n]: yReceiving c1841-ipbase-mz.123-14.T7.bin from 192.168.20.254 !!!!!!!!!!!!!!!!!!!!!!File reception completed.Copying file c1841-ipbase-mz.123-14.T7.bin to flash.Erasing flash at 0x607c0000program flash location 0x605a0000Recovering an IOS Image Using XmodemIf for some reason you are not able to use the Fast Ethernet interfaces on a router, you can recoveran IOS image by transferring it over a console cable by using Xmodem. The method is muchslower than using tftpdnld because you are transferring at 9600 bps instead of 100 Mbps.To use Xmodem, connect a console cable and open up a terminal session with the router. Then usethe xmodem command as demonstrated in Example 15-10.Example 15-10Using xmodem to Recover an IOS Imagerommon1>xmodem -c c1841-ipbase-mz.123-14.T7.binDo not start the sending program yet...device does not contain a valid magic numberdir: cannot open device “flash:”WARNING: All existing data in bootflash will be lost!Invoke this application only for disaster recovery.Do you wish to continue? y/n [n]: yReady to receive file c1841-ipbase-mz.123-14.T7.bin