[ECOS] Debug network application problem?

[ECOS] Debug network application problem?

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Hi everyone:
    I am porting eCos on my custom MPC823 board.
I encounter a problem. I create an application with network supported
( example of twothreads and add init_all_network_interfaces(); in
cyg_user_start)
If I download the twothreads program via ethernet by powerpci-eabi-gdb.
I can ping the redboot IP & application IP.
But if I download the twothreads program via serial by powerpci-eabi-gdb.
I can't ping the redboot IP & application IP. (but application running)
If I download via tftp by redboot ( lo -v twothreads.srec ), the application
can't run.

What's the problem ??

Thank you very much!!

Ken

ps. the initial option for eth0 = CYGHWR_NET_DRIVER_ETH0_ADDRS
the message showing below
Network stack using 65536 bytes for misc space
                    65536 bytes for mbufs
                    131072 bytes for mbuf clusters
BOOTP[eth0] op: REPLY
       htype: Ethernet
        hlen: 6
        hops: 0
         xid: 0x0
        secs: 0
       flags: 0x0
       hw_addr: FF:FF:FF:FF:FF:FF
     client IP: 140.96.103.99
         my IP: 140.96.103.99
     server IP: 140.96.103.131
    gateway IP: 140.96.103.254
  options:
        subnet mask: 255.255.255.0
       IP broadcast: 140.96.103.255
            gateway: 140.96.103.254
Route - dst: 127.0.0.0, mask: 255.0.0.0, gateway: 127.0.0.1