Re: [v6ops] WGLC: draft-ietf-v6ops-unique-ipv6-prefix-per-host-02 - multiple prefixes per device

[Mark Andrews <[e-mail]>]

In message <[e-mail]>, Brian E Carpenter 
writes:
> On 17/03/2017 09:14, Gert Doering wrote:
> > Hi,
> > 
> > On Fri, Mar 17, 2017 at 06:31:43AM +1300, Brian E Carpenter wrote:
> >> So, it seems clear to me that while getting a /64 is better than getting
> >> a /128, it's even better to get a /56. Or even one of those 15 trillion /4
> 8s.
> >> We should make it clear that /64 is not even second-best. Just better
> >> than /128.
> > 
> > "give any *host* that connects a /48" (and dimension pools on WiFi
> > hotspots etc. big enough to actually be able to do this) might actually 
> > be a good way to ensure IPv6 is going to run out faster than expected...
> > 
> > IOW, be careful with the maths here.
> 
> Yes, one always needs cautious allocation policies. But still... /64
> is not enough in the general case, with today's link-layer media
> and today's IPv6 stacks. (We can have the argument about tomorrow
> some other time. :-)

And PD allows for a node to do multiple PD requests.  Each router
doesn't need a pool of prefixes to answer PD requests from.  It can
do a upstream request to full fill the downstream request on demand.

A coffee shop is a site or part of a site.  That site should have
a /48 with 65536 /64 subnets to further allocate.  Hosts draw from
that pool.  Yes, that does mean that there are lots of intra site
routing entries for /64's rather than for shorter prefix lengths.
That however shouldn't matter because it is not a excessive number
for even the most inexpensive router to handle and they are summaried
as a /48 in the global routing table.  Even with a few of /48 pools
from different ISPs it still isn't excessive.

When a iPhone requests a PD over its cellular interface it is acting
as a border router.  When it requests a PD over its WiFi interface
(because some app wants lots of addresses or to connect the BT to
the WiFi) it is acting as a interior router.

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
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