我使用NE64，调试程序时，从串口输出以下信息：

EtherOpen(start...)
mdcsel= 05; bufmap= 04; maxfl= 0600
MAC ADDR 000B 06E3 407B
EtherType =  00;  Programmable etype =  0000
rxmode= 00
netctl 02 Full-Douplex mode
EtherOpen(end)

--MII write--
--MII read--DATA=  7F00

--MII read--DATA=  2100

--MII write--
--MII read--DATA=  7F00
Initializing ARP..........
Initializing UDP....
UDP Initialized
Initializing UDP demo client
Searching for free UDP socket...
Free socket found
>>>>>>>>>Entering to MAIN LOOP>>>>>>>>>

***EPHY_ISR

--MII read--DATA=  7F10

PHY Interrupt:
 =================
  ###PHY_R16_LKC=LINK CHANGE###
--MII read--DATA=  2100

@@@@LINK IS UP@@@@

--MII read--DATA=  2100

 =================
***EPHYisr_ENDSending UDP...
Trying to find MAC address from ARP Cache
Need to send ARP Request to local network..
--TXstart--
***EMAC_TX_COMPLETE_ISR***isr_END-TXEND-ARP Request Sent
ARP or lower layer not ready, try again

然后就一直循环输出

Sending UDP...
Trying to find MAC address from ARP Cache
Address In Cache
Address in cache but unresolved
ARP or lower layer not ready, try again

不知道什么原因？高手给提示一下