[157913] in North American Network Operators' Group
Re: What is BCP re De-Aggregation: strict filtering /48s out of /32
daemon@ATHENA.MIT.EDU (William Herrin)
Wed Nov 14 19:19:45 2012
In-Reply-To: <19C3960E-2E90-4965-BF16-8A5B40B5B923@mac.com>
From: William Herrin <bill@herrin.us>
Date: Wed, 14 Nov 2012 19:19:04 -0500
To: Michael Smith <mksmith@mac.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Wed, Nov 14, 2012 at 6:31 PM, Michael Smith <mksmith@mac.com> wrote:
>
> On Nov 14, 2012, at 1:50 PM, William Herrin <bill@herrin.us> wrote:
>
>> On Wed, Nov 14, 2012 at 3:10 PM, Michael Smith <mksmith@mac.com> wrote:
>>> I guess I'm confused. I have a /32 that I have broken up
>>> into /47's for my discrete POP locations. I don't have a
>>> network between them, by design. And, I won't
>>> announce the /32 covering route because there is
>>> no single POP that can take requests for the entire
>>> /32 - think regionalized anycast.
>>>
>>> So, how is it "worse" to announce the deaggregated
>>> /47's versus getting a /32 for every POP? In either
>>> case, I'm going to put the same number of routes into the DFZ.
>>
>> If you announce an ISP /32 from each POP (or an end-user /48, /47,
>> etc) then I know that a neutral third party has vetted your proposed
>> network configuration and confirmed that the routes are disaggregated
>> because the network architecture requires it. If you announce a /47
>> from your ISP space, for all I know you're trying to tweak utilization
>> on your ISP uplinks.
>
> Again, I thought the discussion was about PI, not PA. I don't announce any PA.
Hi Michael,
PI and PA terminology is getting to be as obsolete as Class A, B and
C. Your IPv6 addresses fall in to one of three categories:
"Allocation" from RIR under ISP rules (/32 or more)
"Assignment" from RIR under end-user rules (/48 or more)
"Reassignment" from ISP (any size)
You will find that you can successfully propagate announcements of
allocations in units of /32 or shorter, assignments in units of /48 or
shorter and reassignments in units of /32 or shorter.
Longer prefix announcements won't be rejected by everybody, but
they'll be rejected by enough folks to spoil your day.
So, regardless of which of the three types of addresses you work with,
you should make sure to get enough so that each of your discrete
multihomed networks can announce a prefix as big as or bigger than the
minimum.
And as a purely pragmatic matter, you should never ever try to number
a discrete multihomed IPv6 network using a reassignment. Go get an
allocation or assignment (as appropriate) from the RIR instead.
Regards,
Bill Herrin
--
William D. Herrin ................ herrin@dirtside.com bill@herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004
