[U-Boot] about uboot leads to LAN disconnected

[wanghgsz]

Dear all,
       Device is a camera connected LAN, camera  board  CPU is  RT5350(based on MIPS) .
     I have met a problem about uboot. uboot leads to LAN disconnected in the following cases. 
     I have been looking forward to answers.
   with best wishes


    
case 1 :   when  CRC checksum  bad
Please choose the operation:
   1: Load system code to SDRAM via TFTP.
   2: Load system code then write to Flash via TFTP.
   3: Boot system code via Flash (default).
   4: Entr boot command line interface.
   7: Load Boot Loader code then write to Flash via Serial.
   9: Load Boot Loader code then write to Flash via TFTP.
 0


3: System Boot system code via Flash.
## Booting image at bc050000 ...
raspi_read: from:50000 len:40
.   Image Name:   Linux Kernel Image
   Created:      2013-03-14   6:22:22 UTC
   Image Type:   MIPS Linux Kernel Image (lzma compressed)
   Data Size:    3113308 Bytes =  3 MB
   Load Address: 80000000
   Entry Point:  802fb000
raspi_read: from:50040 len:2f815c
................................................   Verifying Checksum ... Bad Data CRC




case 2  when modify parameters spend over 10 seconds


1: System Load Linux to SDRAM via TFTP.
 Please Input new ones /or Ctrl-C to discard
        Input device IP (192.168.0.121) ==:192.168.0.121
        Input server IP (192.168.0.66) ==:192.168.0.66