Issues encountered with assigning .0 and .255 as usable addresses?

bmanning at vacation.karoshi.com bmanning at vacation.karoshi.com
Tue Oct 23 23:03:55 UTC 2012


ok...  so lets look at some space here.

98.32.0.0/22

98.32.0.0/32 is clearly on the unusable boundary.
what about 
98.32.0.255/32  & 98.32.1.0/32 ???

98.32.4.255/32 is also clearly on the unusable boundary...  UNTIL   

the delegation moves from a /22 to a /21.  Then its usable.

clear?  thought so.

/bill


On Tue, Oct 23, 2012 at 10:00:53PM +0200, Tore Anderson wrote:
> * Job Snijders
> 
> > In the post-classfull routing world .0 and .255 should be normal IP
> > addresses. CIDR was only recently defined (somewhere in 1993) so I
> > understand it might take companies some time to adjust to this novel
> > situation. Ok, enough snarkyness!
> > 
> > Quite recently a participant of the NLNOG RING had a problem related
> > to an .255 IP address. You can read more about it here:
> > https://ring.nlnog.net/news/2012/10/ring-success-the-ipv4-255-problem/
> 
> AIUI, that particular problem couldn't be blamed on lack of CIDR support
> either, as 91.218.150.255 is (was) a class A address. It would have had
> to be 91.255.255.255 or 91.0.0.0 for it to be special in the classful
> pre-CIDR world.
> 
> That said, it's rather common for people to believe that a /24 anywhere
> in the IPv4 address space is a +class C; so I'm not really surprised.
> 
> -- 
> Tore Anderson
> Redpill Linpro AS - http://www.redpill-linpro.com/



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