Hi,
I think you could use etharp_find_addr to read the ARP table :
s
/**
* Finds (stable) ethernet/IP address pair from ARP table
* using interface and IP address index.
* @note the addresses in the ARP table are in network order!
*
* @param netif points to interface index
* @param ipaddr points to the (network order) IP address index
* @param eth_ret points to return pointer
* @param ip_ret points to return pointer
* @return table index if found, -1 otherwise
*/
s8_t etharp_find_addr(struct netif *netif, struct ip_addr *ipaddr, struct
eth_addr **eth_ret, struct ip_addr **ip_ret);