I am doing now network background agreement, the agreement itself has no problems, hardware and software for STM32F207 + HAL + + DP83848 LWIP, phenomenon is if didn't insert in the electric cable (cable on the other side needs to connect routers), programs run until after the insertion, ip_route_get_local_ip (& amp; PCB - & gt; Local_ip, & amp; PCB - & gt; Remote_ip, netif, local_ip) function can't get to the local IP and port number,
# define ip_route_get_local_ip (SRC, dest, netif, ipaddr) do {\
(netif)=ip_route (SRC, dest); \
Ipaddr=ip_netif_get_local_ip (netif, dest); \



# define ip_route (SRC, dest) \
Ip4_route_src (dest, SRC)
# define ip_netif_get_local_ip (netif, dest) \
Ip4_netif_get_local_ip (netif)


But if began to insert the cable, even if in the process of back plug cable, also won't affect the local IP access,