Probably because the entire TCP/IP stack of Vista is new from the ground up.

Windows XP's network stack is a bit old (I think it came from Windows 95, or
at least Windows NT 4.0), so the ARP packet may be an older, no longer in
use functionality.

Bill F.

"Polaris" wrote in message
...
Hi Experts:

I have noticed some differences on Windows Vista regarding to the
gratuitous ARP: I have a virtual adapter, under Windows XP, when IP Helper
function "IpRenewAddress" is called for the virtual adapter, gratuitous
ARP packet is generated by the system; but under Windows Vista, this seems
is not happening. Does this make sense? Can this be explained?

Thanks in Advance!
Polaris