3Com 3C16850, Installation Manual

Page: 53 / 70

Upgrading Software 53
Starting at 0x60000...
The primary image name is saved in flash memory, the secondary image name is
saved in the EPPROM. However, if you use the
display boot command to display
the boot image it will only read from flash so only the primary image will be
displayed. The secondary boot image name cannot be displayed when there is an
image error.
Upgrading Software
Using Xmodem
The Xmodem protocol transmits files through serial ports and supports both
128-byte and 1K-byte packets. Xmodem also supports two types of check; normal
checksum and CRC. When there is a packet error, retransmission is supported,
normally 10 times.
The Xmodem protocol completes transmission by receiving and sending programs.
The receiving program first sends the negotiating characters to negotiate the
check means. After passing the negotiation, the sending program begins to send
the packet.
The receiving program checks the packet according to the negotiated means after
receiving a complete packet. The acknowledgement characters are sent after
passing the check and then the sending program continues to send the next
packet. If the check fails, negative characters are sent and the sending program
sends the packet again.
1 Enter
1
in the BOOT Menu and press Enter . The system accesses the download
application file menu:
1. Set TFTP protocol parameter
2. Set FTP protocol parameter
3. Set XMODEM protocol parameter
0. Return to boot menu
Enter your choice (0-3):
2 Enter
3
in the download program menu.
3 Select the Xmodem protocol to implement the software upgrade.
4 Press Enter . The system enters the download rate-setting menu:
Please select your download baudrate:
1. 9600
2. 19200
3. 38400
4. 57600
5. 115200
0. Exit
Enter your choice (0-5):
5 Select the appropriate download speed. For example, enter
5
to select a download
speed of 115200bps.
6 Press Enter . The terminal displays the following information:
Download baudrate is 115200 bps. Please change the terminal’s
baudrate to 115200 bps, and select XMODEM protocol.
Press enter key when ready.