> Subnetting with 255.255.255.128 works fine here. Which RFC says you
> need to use sets of two bits? I looked around a bit and didn't find it --
> the only "rules" I ran across were a suggestion that subnet masks should
> be contiguous.
Check out RFC950. RFC950 is the stadnard for subnetting.
>From RFC950:
In certain contexts, it is useful to have fixed addresses
with functional significance rather than as identifiers of
specific hosts. When such usage is called for, the address
zero is to be interpreted as meaning "this", as in "this
network". The address of all ones are to be interpreted as
meaning "all", as in "all hosts". For example, the address
128.9.255.255 could be interpreted as meaning all hosts on
the network 128.9. Or, the address 0.0.0.37 could be
interpreted as meaning host 37 on this network."
It is useful to preserve and extend the interpretation of these
special addresses in subnetted networks. This means the values
of all zeros and all ones in the subnet field should not be
assigned to actual (physical) subnets.
Clearly, if the subnet field is only one bit, then it is always either all
ones or all zeros.
Note also, that the rfc explicitly allows non-contiguous subnet fields.
Note further, I have seen vendors systems and routers that fail miserably
if you do either of these things, (i.e have non-contiguous subnet fields, or
have a single bit field).
Brian Utterback blu @
mc .
com Manager Technical Networks
Mercury Computer Systems, Inc. (508) 256-1300x168
199 Riverneck Road (508) 256-3599 FAX
Chelmsford, MA 01824 You can't grep dead trees.
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