请教一个UDP包发送的问题

我用KDatagramSocket的sendto 发包，OnReceive收包，但是好像传输超过1500字节的UDP包就只能发送前面的部分。除了打破UDP报，还有什么其他办法啊？

还有就是帮助中关于Onreceive()中的帮助谁能帮我解释一下？到底Available表示什么啊？
UDP包长度？还是缓冲区大小？这个是不是解决包比较大的情况阿？rt
OnReceive() is called by the framework to indicate the reception of a complete
 TSDU (datagram) by the transport. The user overrides OnReceive() to implement
 custom receive processing. After examining the buffer indicated by Data,
 the user should return a number of bytes consumed. Typically it is equal
 to Indicated.

On some occasions, the transport might not indicate a complete datagram,
i.e. Available > Indicated. In this case, the client should provide a page
-locked buffer specified by output parameters RcvBuffer/RcvBufferLen, to
accept the remainder of the TSDU. When the transport completes the request
, another overridable handler, OnReceiveComplete() is called. If the client
 fails to provide the buffer, the receive data can be lost.

OnReceive() is called at the DISPATCH_LEVEL. Whenever a lengthy processing
 is required, the driver should copy the indicated data and schedule a work
 item to do so.