Minimum IPv6 size

Sat Oct 3 21:29:41 UTC 2009

Hello,

Kevin Oberman wrote:
>> Date: Sat, 03 Oct 2009 09:27:27 +0100
>> From: James Aldridge <jhma at mcvax.org>
>>
>> --On 2 October 2009 16:43:14 -0700 Kevin Oberman <oberman at es.net> wrote:
>>> Depends on the address space it is assigned from. Most specify a maximum
>>> prefix length of 32, but the micro-allocations and the allocations for
>>> PI dual-homing are /48.
>>> We consider the following to be "legal":
>>>                 /* global unicast allocations */
>>>                 route-filter 2001::/16 prefix-length-range /19-/35;
>>>                 /* 6to4 prefix */
>>>                 route-filter 2002::/16 prefix-length-range /16-/16;
>>>                 /* RIPE allocations */
>>>                 route-filter 2003::/18 prefix-length-range /19-/32;
>>>                 /* APNIC allocations */
>>>                 route-filter 2400::/12 prefix-length-range /13-/32;
>>>                 /* ARIN allocations */
>>>                 route-filter 2600::/12 prefix-length-range /13-/32;
>>>                 /* ARIN allocations */
>>>                 route-filter 2610::/23 prefix-length-range /24-/32;
>>>                 /* LACNIC allocations */
>>>                 route-filter 2800::/12 prefix-length-range /13-/32;
>>>                 /* RIPE allocations */
>>>                 route-filter 2A00::/12 prefix-length-range /13-/32;
>>>                 /* AfriNIC allocations */
>>>                 route-filter 2C00::/12 prefix-length-range /13-/32;
>>>                 /* APNIC PI allocations */
>>>                 route-filter 2001:0DF0::/29 prefix-length-range /40-/48;
>>>                 /* AFRINIC PI allocations */
>>>                 route-filter 2001:43F8::/29 prefix-length-range /40-/48;
>>>                 /* ARIN PI allocations */
>>>                 route-filter 2620::/23 prefix-length-range /40-/48;
>>>                 /* ARIN Micro-allocations */
>>>                 route-filter 2001:0500::/24 prefix-length-range /44-/48;
>>>
>>> This means accepting prefixes ARIN says we should not, but ARIN does not
>>> set our routing policy and I will be on a panel on that issue at NANOG in
>>> Dearborn later this month.
>>
>> It might be worth relaxing filtering within 2001::/16.  The RIPE NCC 
>> appears to be making /48 PI assignments from within 2001:678::/29 (e.g. the 
>> RIPE Meeting next week will be using 2001:67c:64::/48)
> 
> Looks like we need to relax 2001:678::/29 a bit, but I am not sure that
> we will open up the entire /16. I already have such for ARIN, AfriNIC,
> and APNIC.
> 
> Is there some central repository for information on this? We usually
> seem to find out about such changes out of the ARIN region a bit after
> the fact.

each RIR has an overview of their managed address space with the longest
prefixes they are assigning/allocating from their ranges. I currently use those
overviews to build IPv6 BGP filters manually. If you build very strict filters,
you have to check the overviews more often as with loose filters.

https://www.ripe.net/ripe/docs/ripe-ncc-managed-address-space.html
http://www.arin.net/reference/ip_blocks.html
http://www.arin.net/reference/micro_allocations.html
http://www.apnic.net/db/min-alloc.html
http://lacnic.net/en/registro/index.html
http://www.afrinic.net/Registration/resources.htm

There ist also a loose and a strict filter recommendation by Gert Doering [1],
but the strict filter is very strict at the moment. It allows only /48s from
RIPEs IPv6 PI space 2001:678::/29 for example, although RIPE currently also
assignes /47 or /46 from this range. Also there should be some deaggregation
allowed. When RIPE allocates a /32 to a LIR and LIR has to deaggregate it for
some reason, because he cannot get a second /32, he should be able to use (eg.)
4 bits for deaggreation. I don't want to see a /48 where RIPE allocates only /32
prefixes, but I would accept prefixes up to a /36.

[1] http://www.space.net/~gert/RIPE/ipv6-filters.html

Regards,

Christian Seitz