The GetIpNetTable function retrieves the IP-to-physical address mapping table:

DECLARE INTEGER GetIpNetTable IN iphlpapi;
	STRING  @ pIpNetTable,;
	INTEGER @ pdwSize,;
	INTEGER   bOrder

MSDN link to this function:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/iphlp/iphlp/getipnettable.asp

FoxPro code sample (News2News, membership area):
Retrieving the IP-to-physical address mapping table
http://www.news2news.com/vfp/?example=230&function=369

VB code sample (AllApi, free)
Address Mapping Table
http://www.mentalis.org/apilist/GetIpNetTable.shtml