Re: Is it safe to use 240.0.0.0/4

[Damian Menscher via NANOG <nanog () nanog org>]

Not used in the sense you imagine, but I designed a hack where we hash IPv6
addresses into 224/3 (class D and E space) so backends that don't support
IPv6 can still be provided a pseudo-IP.  This accelerated support of IPv6
across all Google services without needing to wait for each individual
backend to provide support.

See
https://www.nanog.org/meetings/nanog50/presentations/Wednesday/NANOG50.Talk41.colitti-IPv6%20transition%20experiences.pdf
slide 4 for a description, or
http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/net/InetAddresses.html
for open-sourced code.

There may be other uses for IPs beyond routing.

Damian

On Wed, Jun 17, 2015 at 2:07 PM, Luan Nguyen <lnguyen () opsource net> wrote:

> Is that safe to use internally? Anyone using it?
> Just for NATTING on Cisco gears...