Is it safe to use 240.0.0.0/4

Wed Jun 17 23:25:34 UTC 2015

In message <CAD6AjGSBfy_RH9J_T2yY32=vqH=19JBeL+gSNB4nN_piJv+16A at mail.gmail.com>, Ca By writes:
> 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

Well the cell carriers are kind of forcing the issue here for iOS.
They want to go IPv6-only and Apple doesn't want to do 464XLAT last
I heard (haven't watched the video yet).  If all the apps can run
in a IPv6 only environment then there is only IPv4 literals in web
pages and tethered equipement to worry about so there is less presure
to implement 464XLAT.

Breaking pages with IPv4 literals may actually be a good thing at
this stage.  We are 20 years into the migration to IPv6.  15 years
of production IPv6 behind us.

Most tethered equipment can do IPv6.  The only hold outs there are
servers that they want to connect to are IPv6 only.  Forcing the
issue here would also be a good thing.

Additionally lots of big companies (FaceBook, Microsoft) are trying
to go IPv6 only internally as are data centers.

A number of wireline ISP are IPv6 only using DS-Lite to transport
IPv4.  MAP is a future IPv4 as a service on IPv6 contender.

> 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/>
> >
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org