Bob McGregor writes (quote repositioned for clarity):

>[Gavin writes:]
>>Apparently, both the host part of the address and the *subnet* part must
>>reserve both all zeros and all ones as broadcast addresses.  This mans that
>>you *can't* split a class C address exactly in half, as you would only have
>>a single bit for the subnet part of the address, and both possible values
>>would be reserved for broadcast addresses!
>
>IP Subnet 0 is now possible if you have newer routers.  We use it here for
>about 8 class  C address and have had no problems what so ever.  We subnet it
>between 1-126 and 129-254(usable ip's) and it works great.
>
>It is a newer cabability but we've been doing it for 2+ years with no
>problem.  The subnet mask is 255.255.255.128

The problem is the ambiguity in the broadcast addresses as seen from
outside the network. Since most gateway routers disallow broadcast
addresses as inbound destinations (or should by now), you can use the
"illegal" subnets within your own network.

-- Bruce


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