Hi,I'm trying to implement IP subnetting in my application and am having someproblems understanding the changes to the TCP/IP stack since XP. I want to be able to send subnet broadcasts and network broadcasts but not the all one's broadcast. I've implemented the subnets as follows: Class A Subnets (although I get the same issue with class B) Vista Machine - 10.254.254.2 - 255.255.255.0 XPMachine -10.254.254.3 - 255.255.255.0 XPMachine -10.254.254.4 - 255.255.255.0 ThreadXMachine- 10.254.1.1 - 255.255.255.0 ThreadXMachine- 10.254.2.1 -255.255.255.0 It is desirable to send local subnet broadcasts, i.e. 10.254.X.255 and also a network broadcast, i.e. 10.255.255.255. I am able to send and receive the desired broadcasts between all machines runningXP and ThreadX. The problems I have when having to support Vista is that the Network broadcasts do not get transmitted from Vista machines, so no records are visible in my Network monitoring Tool (on the Vista machine) and the packets do not show up on any other non-Vista machine that listens for them. Secondly, when it comes to receiving, the broadcast packets (to address 10.255.255.255) can be seen arriving on my Vista machine, as the appear in Wireshark (Network Monitoring Tool), but they do not get passed on to my application. When I send the subnet broadcast, i.e. 10.254.254.255, then all machines transmit and receive the packets as expected. Is there anyway of getting round this, i.e. making the Vista stack behavemorelike XP?Can anyone helpplease? Thanks,Ollie