[56882] in North American Network Operators' Group
Re: APNIC returning 223/8 to IANA
daemon@ATHENA.MIT.EDU (Stephen J. Wilcox)
Thu Mar 20 16:05:26 2003
Date: Thu, 20 Mar 2003 21:03:10 +0000 (GMT)
From: "Stephen J. Wilcox" <steve@telecomplete.co.uk>
To: bdragon@gweep.net
Cc: nanog@merit.edu
In-Reply-To: <20030320195145.67333.qmail@sidehack.sat.gweep.net>
Errors-To: owner-nanog-outgoing@merit.edu
I think your getting confused?
The restriction is on subnets using classful addresses, you shouldnt use all
zeros and all ones subnet for a given subnetted classful network.
In the examples below, 192.0.0.0 and 192.0.255.0 are valid Class C networks..
however if you then go classless and presumably enable ip subnet-zero on your
cisco routers as well then no such restrictions exist including on 1.0.0.0/24 or
223.255.255.255.0/24.
On Thu, 20 Mar 2003 bdragon@gweep.net wrote:
>
> > Its not quite that simple folks. The reason this particular
> > block is reserved has some real technical merit, while the 69/8
> > muddle is strictly due to ISP negligence.
> >
> > RFC 3330 got it wrong. Anyone remember the "Martian List"
> > from the 1970-1990's? Trying to use the all-ones or all-zeros
> > network for real traffic is not possible. Pre CIDR it was
> > not possible to use 192.0.0.0/24 or 192.0.255.0/24. (the same was
> > true on -every- network boundary) With CIDR,
> > those boundaries moved to 1.0.0.0/24 and 223.255.255.0/24
> > e.g. only two reservered blocks instead of hundreds.
> >
> > Simply having someonechange a DB entry or create an RFC will
> > not affect the installed silicon base. Won't work.
> > APNIC is on the moral highground here. They received damaged
> > goods without notification. IANA needs better technical clue.
> >
> > --bill
>
> Unless I'm mistaken, there is no technical issue with using the
> All-0's or All-1's classful networks. In fact, several of those networks
> are in use.
>
> 0.0.0.0/8 "this" network (all-zeros A)
> 127.0.0.0/8 loopback network (all-ones A)
> 128.0.0.0/16 reserved but unused (all-zeros B)
> 191.255.0.0/16 reserved but unused (all-ones B)
> 192.0.0.0/24 reserved but unused (all-zeros C)
> 223.255.255.0/24 reserved but unused (all-ones C)
>
> As with 0/8 and 127/8, the other 4 networks could certainly be
> designated for some use, including "normal" end-users. This type of
> end-user usage would even continue to work with old classful gear.
>
>
