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

[David Lang]

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 en linux.ee>
> To: linux-kernel en 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 en tartu.cyber.ee)
> 
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