[Novalug] Question

Richard Barnes richard.barnes@gmail.com
Sun Mar 1 23:24:26 EST 2009


Kyle,

I apologize if I created the impression that I was trying to spread
misinformation.   It's worth noting though, that the word "subnet" is
used in at least three senses:

1. One sense is of the word "subnet" is to say that a host belongs to
a subnet if it can talk to other hosts in that subnet without having
to go through a router (or through a certain number of routers).  This
sense of the term make more sense when you're thinking about how
packets actually get routed.

2. Another use of the word is to just to talk about the address
ranges, i.e., pools of addresses.  If the DHCP server is providing
addresses in the range 192.168.0.0-127 and the static addresses are in
the range 192.168.0.128-255, then former could be said to be in the
subnet 192.168.0.0/25 and the latter in 192.168.0.128/25, even though
both of these are within the subnet 192.168.0.0/24.  This sense of the
term makes sense if you're just describing sets of addresses.

3. A third use of the word is in a sense a specialization of the
second, in that a network admin is "using a subnet" (where
subnet=prefix) if he's assigning hosts on his network addresses from
that subnet.  This sense of the term makes sense for talking about how
network managers manage their address space.

I get the sense that you were thinking in terms of (1) or (3), whereas
I was thinking of (2).  I don't think we're really in conflict here,
just talking past each other.  Let me know if I'm way off base.

Cheers,
--Richard


On Sun, Mar 1, 2009 at 11:01 PM, Kyle Powell <kyle_powell@yahoo.com> wrote:
>
> It's not a nit and I applaud John for trying to correct the misinformation you're spreading on this list.
>
>> > On Mar 1, 2009, at 11:33 AM, Richard Barnes wrote:
>> > (Actually, limiting DHCP and fixed to separate ranges is effectively
>> > the same thing as making them different subnets.
>
> This is absolutely incorrect. If I'm using the subnet 192.168.0.0/24 and I setup a dhcp server to hand out addresses from a pool of 192.168.0.100 to 192.168.0.199, allowing the rest of the addresses on that subnet to be used for static addresses, they're all still on the same subnet.
>
> -Kyle
>
>
>
>



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