SMURF amplifier block list

Jay R. Ashworth jra at
Tue Apr 14 20:56:11 UTC 1998

On Tue, Apr 14, 1998 at 04:52:06PM -0400, James R. Cutler wrote:
> I have a B assignment.  I have switched infrastructure segments
> with /22 masking.  Do you mean to say that the host number
> range on each /22 masked segment is not continuous 1 through 1022,
> but has several holes instead.? The network seems to be working
> properly.  I may be in big trouble!
> None of my TCP/IP courses or books or Cisco CDs have prepared me for 
> such a surprise.  Please point me to a text which will explain this.  

I'm posting this answer to the list just on the off chance I've
misunderstood the world, instead of you.  I'd set followups to
nodlist at, but I think the reflector would strip it off
anyway, so any further traffic on this can drop off NANOG.

IP address octets stop at .255.  Period.  They can't go up to "1022",
and it's probably a less than good idea to write them that way, or even
think of them that way, because no one and no software will know what
to do with them.

The assertion that Steve Sprunk and I, amongst others, were making is
that any host address that ends in .255 is probably a poor address to
assign, and yes, that means that in any network larger than a /24 (IE:
subnetted B's, or /23-/8's, to phrase it another way) that you're going
to lose more than one address per subnet.

My opinion is: this is a lot easier to live with than the possible
problems that can arise from numbering a host X.X.X.255, which are
problems that you _cannot_ correct yourself.  You _can_, however, 
control whether you address hosts that way or not.

Your choice.

-- jra
Jay R. Ashworth                                                jra at
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