用Visual C++实现局域网IP多播,在局域网中，管理员常常需要将某条信息发送给一组用户。如果使用一对一的发送方法， 虽然是可行的，但是过于麻烦，也常会出现漏发、错发。为了更有效的解决这种组通信问题 ，出现了一种多播技术（也常称为组播通信），它是基于IP层的通信技术。-Using Visual C++ LAN IP multicast in the LAN, administrators often need to send a message to a group of users. If you are using one of the transmission method, although it is feasible, but too cumbersome, too often appear omission, wrong hair. To effectively address this group communications, there is a multicast technology (often called a multicast communication), which is based on IP layer communication technologies.