North American Network Operators Group
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Re: traffic filtering

  • From: Joe Abley
  • Date: Tue Jan 22 12:37:16 2002 
On Mon, Jan 21, 2002 at 05:53:16PM -0500, Stephen Griffin wrote:
> I'm curious about how many networks completely filter all traffic to
> any ip address ending in either ".0" or ".255".

I heard recently that Windows 2000 will refuse to send packets
to addresses with the least-significant octet 255, if the most-
significant octet indicates the address lies in a pre-CIDR class
C. So, for example, 192.168.0.255 would be unreachable from a
windows 2000 machine, regardless of the fact that it might be
a legitimate host numbered within 192.168.0.0/23.

This seems like a strange design decision for windows 2000, if
it's real. But, if it *is* true, the answer to your question "is
this kind of filtering common" might be a strong "yes", at least
in the Microsoft-populated extreme network edge.


Joe