uboot下开发板和PC ping不通该怎么办？

norflash下的uboot启动后，用tftp32往nandflash下程序总是以下这种提示，怎么办？
OpenJTAG> print
bootargs=noinitrd root=/dev/mtdblock3 init=/linuxrc console=ttySAC0
bootcmd=nand read.jffs2 0x30007FC0 kernel; bootm 0x30007FC0
bootdelay=2
baudrate=115200
ethaddr=08:00:3e:26:0a:5b
netmask=255.255.255.0
mtdids=nand0=nandflash0
mtdparts=mtdparts=nandflash0:256k@0(bootloader),128k(params),2m(kernel),-(root)
ipaddr=202.204.53.100
serverip=202.204.53.189
stdin=serial
stdout=serial
stderr=serial
partition=nand0,0
mtddevnum=0
mtddevname=bootloader

Environment size: 447/131068 bytes
OpenJTAG> ping 202.204.53.189
ERROR: resetting DM9000 -> not responding
dm9000 i/o: 0x20000000, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
could not establish link
host 202.204.53.189 is alive
OpenJTAG> tftp 30000000 lcd.bin
ERROR: resetting DM9000 -> not responding
dm9000 i/o: 0x20000000, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
could not establish link
TFTP from server 202.204.53.189; our IP address is 202.204.53.100
Filename 'lcd.bin'.
Load address: 0x30000000
Loading: T T checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
T checksum bad
T T T T T checksum bad
T checksum bad
checksum bad
T checksum bad

Retry count exceeded; starting again
TFTP from server 202.204.53.189; our IP address is 202.204.53.100
Filename 'lcd.bin'.
Load address: 0x30000000
Loading: checksum bad
checksum bad
T T T T T T T T T checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
T checksum bad
checksum bad

Retry count exceeded; starting again
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
TFTP from server 202.204.53.189; our IP address is 202.204.53.100
Filename 'lcd.bin'.
Load address: 0x30000000
Loading: checksum bad
checksum bad
checksum bad
checksum bad
T T T T T T T checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
T checksum bad
T T
Retry count exceeded; starting again
TFTP from server 202.204.53.189; our IP address is 202.204.53.100
Filename 'lcd.bin'.
Load address: 0x30000000
Loading: T T T T T checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
T T T T checksum bad
checksum bad
T checksum bad

Retry count exceeded; starting again
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
TFTP from server 202.204.53.189; our IP address is 202.204.53.100
Filename 'lcd.bin'.
Load address: 0x30000000
Loading: T T T T checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
T T T checksum bad
T