Re: all zeroes/all ones used in host IP's...

From: David Lang (dlang@diginsite.com)
Date: Fri Jan 28 2000 - 18:43:40 EST


some equipment (including Cisco routers if they have older firmware) do
not allow network addresses with 0's in them. with the newer firmware
there is a command you need to include in the configuration to allow it to
use them.

Linux allows them without any problems.

David Lang

 On Fri, 28 Jan 2000, Meelis Roos wrote:

> Date: Fri, 28 Jan 2000 22:01:25 +0200
> From: Meelis Roos <mroos@linux.ee>
> To: linux-kernel@vger.rutgers.edu
> Subject: Re: all zeroes/all ones used in host IP's...
>
> MAH> using "0's" in IP addresses. Nobody could categorically say
> MAH> wether or not they are allowed or not including myself, so I
> MAH> hunted down RFC 1123, and found the relevant section.
>
> It's really 1122 :)
>
> MAH> IP addresses are not permitted to have the value 0 or -1 for
> MAH> any of the <Host-number>, <Network-number>, or <Subnet-
> MHA> number> fields (except in the special cases listed above).
> MAH> This implies that each of these fields will be at least two
> MAH> bits long.
>
> MAH> I interpret the above as meaning that it is not legal to have a
> MAH> network like this:
>
> MAH> 192.168.0.0/24 or 23.0.0.0/24
>
> MAH> with hosts 192.168.0.1 through 192.168.0.254 or with hosts
> MAH> 23.0.0.1 through 23.0.0.254.
>
> Why? 192.168.0.0 is a C class address, so it has the network number
> 192.168.0 which is not 0. As 23.0 is not equal to 0. So they are
> allowed.
>
> --
> Meelis Roos (mroos@tartu.cyber.ee)
>
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