Is it safe to use 240.0.0.0/4

Wed Jun 17 23:01:36 UTC 2015

On Wednesday, June 17, 2015, William Herrin <bill at herrin.us> wrote:

> On Wed, Jun 17, 2015 at 5:38 PM, Ricky Beam <jfbeam at gmail.com
> <javascript:;>> wrote:
> > I'll wait for Curran to pop up with various links to reasons why Class E
> was
> > "abandoned" by ARIN. (short answer: too much broken crap thinks it's
> > multicast!)
>
> Hi Ricky,
>
> You may be confused. ARIN never possessed class E; it's held in
> reserve by IETF. As much as I enjoy a good ARIN bashing, they and John
> Curran are quite faultless here.
>
> IIRC, the short answer why it wasn't repurposed as additional unicast
> addresses was that too much deployed gear has it hardcoded as
> "reserved, future functionality unknown, do not use." Following an
> instruction to repurpose 240/4 as unicast addresses, such gear would
> not receive new firmware or obsolete out of use quickly enough to be
> worth the effort.
>
> Given how slowly IPv6 is deploying, this

Pardon me. But Apple has at least suggested y'all should be ready for
ipv6-only networks, not class E

http://arstechnica.com/apple/2015/06/apple-to-ios-devs-ipv6-only-cell-service-is-coming-soon-get-your-apps-ready/

http://www.internetsociety.org/deploy360/blog/2015/06/apple-will-require-ipv6-support-for-all-ios-9-apps/

And the source video which is worth watching from start to finish

https://developer.apple.com/videos/wwdc/2015/?id=719

choice may prove to have been
> shortsighted. Had IETF designated class-E as "reserved, future
> unicast" in 2008 when the issue was debated and asked vendors to
> update their software to expect 240/4 to be used as unicast addresses,
> half the problem equipment would already have aged out and we could
> all be debating whether to make them more RFC-1918 or hand them off to
> the RIRs.
>
> Regards,
> Bill Herrin
>
>
>
> --
> William Herrin ................ herrin at dirtside.com <javascript:;>
> bill at herrin.us <javascript:;>
> Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/>
>