nanog mailing list archives

Re: The use of .0/.255 addresses.


From: Richard A Steenbergen <ras () e-gerbil net>
Date: Sat, 26 Jun 2004 22:03:49 -0400


On Sun, Jun 27, 2004 at 12:32:40AM +0100, Jonathan McDowell wrote:

Have just spent some time trying to track down what seemed to be an
elusive problem, I thought I'd mention it here.

I've had problems accessing www.level3.net, www.ebay.co.uk and
www.dabs.com (and a few others I don't recall). As I'm the first user of
a reasonably new netblock I thought it might be something to do with
filters on our upstreams or similar. Trying an IP from our older
netblock worked without problems, which seemed to back this up.

However eventually I tracked it down to the use of the .0 address from
the new netblock; changing to use the .1 address meant I could access
the above sites without any difficulty.

Various people I've asked about this have said they wouldn't use the .0
or .255 addresses themselves, though couldn't present any concrete info
about why not; my experience above would seem to suggest a reason not to
use them.

This is what happens when your educational system continues to teach 
classful routing as anything other than a HISTORICAL FOOTNOTE 
*coughCiscocough*. This is also how you end up with 76k /24s in the global 
routing table.

Do you part to help control the ignorant population: whenever you hear 
someone say "class [ABC]" in reference to anything other than a historical 
allocation, smack them. Hard.

-- 
Richard A Steenbergen <ras () e-gerbil net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)


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