IPv6, multihoming, and customer allocations

Joel Jaeggli joelja at bogus.com
Tue Mar 16 21:01:25 UTC 2010



On 03/16/2010 07:38 AM, Rick Ernst wrote:
> Regurgitating the original e-mail for context and follow-up.
> 
> General responses (some that didn't make it to the list):
>   - "There really is that much space, don't worry about it."
>   - /48s for those that ask for it is fine, ARIN won't ask unless it's a
> bigger assignment
>   - /52 (or /56) on smaller assignments for conservation if it makes you
> feel better
>   - Open question on whether byte/octet-boundary assignment (/56 vs /52) is
> better for some reason
> 
> I haven't seen anything on the general feel for prefix filtering.  I've seen
> discussions from /48 down to /54.  Any feel for what the "standard" (widely
> deployed) IPv6 prefix filter size will be?

I filter at /48. I would consider filtering on something shorter for
assignments of /32 or shorter if there were obvious bad behaver's. We do
advertise more specific /36s but we also have the covering /32.

> Thanks,
> 
> 
> On Sat, Mar 13, 2010 at 10:49 PM, Rick Ernst <nanog at shreddedmail.com> wrote:
> 
>>
>> A couple of different incantations searching the archive didn't enlighten
>> me, and I find it hard to believe this hasn't been discussed.  Apologies and
>> a request for pointers if I'm rehashing an old question.
>>
>> As a small/regional ISP, we got our /32 assigned and it's time to start
>> moving forward (customers are asking for it).  New hardware, updated IOS,
>> etc. are in the pipe.  Discussions are beginning with our upstream providers
>> for peering.  Now, what do we do?
>>
>> A /48 seems to be the standard end-user/multi-homed customer allocation and
>> is the minimum allocation size from ARIN.  A /32 provides 65K /48s so, in
>> theory, we could give each of our customers a /48 and still have room for
>> growth.  A /48 also appears to be generally accepted as the the longest
>> prefix allowed through filters (although /49 through /54 are also
>> discussed).  Most customers, however, won't be multi-homed.
>>
>> Partly from an IPv4 scarcity perspective, and partly from general
>> efficiency and thrift, it seems awfully silly to hand out /48s to somebody
>> that may have a handful of servers or a couple of home machines, especially
>> with special addressing like link-local if the hosts are not expected to be
>> internet reachable (back-end servervs, etc).
>>
>> Based on the above, I'm looking to establish some initial policies to save
>> grief in the future:
>> - /52 allocations to end-users (residential, soho, etc.)
>> - /48 allocations to those that request it
>> - If you are going to multi-home, get your own space
>>
>> This is obviously a very broad brush and takes an insanely large addressing
>> model and makes it even larger (assigning /52s instead of /48s) but, to me
>> at least, it seems reasonable for a first-pass.
>>
>>  For context/scope, we currently have the equivalent of a bit more than the
>> equivalent of a  /16 (IPv4) in use.
>>
>> Thanks,
>>
>>
> 




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