RE: Using x.x.x.0 and x.x.x.255 host addresses in supernets.

["David Schwartz" <davids () webmaster com>]

> Historically, .0 and .255 have been avoided because a lot of servers
> (windows) wouldn't work using that as a host address or would flag it
> as invalid if you tried to connect to it or a myriad of other
> problems. Note that this was a limitation of the host, not anything to
> do with the network or any of the network equipment.
>
> This issue has not existed with any prevelance for quite some time and
> almost everything of recent manufacture is quite happy to be assigned
> in a supernet as well as on the .0 and .255 addresses.
>
> So my oppinion is don't hesistate to use it until you find a real,
> reproducible problem.
>
> -Wayne

I have seen networks where traffic to these addresses was filtered in an
attempt to mitigate broadcast address amplification. Typically, end users
filter their inbound Internet traffic to their own addresses. They know they
don't use .0 or .255 addresses and they found this is a quick way to prevent
any nodes on their internal network from being used as amplifiers without
having to audit/fix their entire internal network.

As we know, the "workaround" may remain in their edge router(s) long after
it has outlived its usefulness.

A few years ago, I noticed that an ISP blocked all traffic from its
customers bound for any .0 or .255 address to prevent drones from flooding
those addresses. I doubt this is typical, but I bet it's still around in at
least a few places.

If you're seriously considering using these addresses, these are other
possible issue you need to consider.

DS