Proposal for allocation of AS numbers - 44net

9 Dec 2015


      Some of the radio networks implementing AMPRnet use BGP as a routing protocol, and therefore
require some AS numbers that should be unique within those networks.   Note I am not referring
to BGP routing on internet, but only within local radio networks.   There usually are one
or more gateways that are connecting those networks to internet, but BGP routing information
is not carried across them, they only route a fixed subnet and may or may not use BGP on the
inside as well.
It is customary to use AS numbers from the "private AS ranges"  on those radio networks
documented in RFC6996: 64512 - 65534 and 4200000000 - 4294967294.
The first (old) range has 1023 available numbers, so it requires some registry where individual
areas can get numbers allocated to them to guarantee the uniqueness of the numbers within the
network.   As always, the policies of such registries lead to discussion and feelings, and
I like to solve that by making the allocation fixed up to the regional level, so everyone can
determine their own numbers without having to agree with others how it is done exactly and
how many numbers each one requires and will get, and whether they need to be changed.
Since 2009, BGP implementatations must support 32-bit AS numbers, and the second larger range
has become available.
My proposal is to map the assigned IP address ranges for countries and states directly to AS
numbers in this AS range.
Advantages:
- the range of AS numbers automatically remains contiguous for countries and regions.
- no need for an "international" registry, and probably not even for a "national" registry.
- local operators can derive the AS number for their region from the local subnet address.
- very sparse use of the available space makes for very low chance of conflicts, even in the
   presence of other private AS numbers that were allocated outside of this system.
- future proof as there is no 1023-AS limit for the AMPRnet radio networks.
- very easy to mnemonically map an AS number seen in a table or trace to the place where
   it is allocated, without need to refer to an allocation database.
I propose the following AS number structure:
For an IP network with the address 44.xxx.yyy.0/zz, the AS number will be: 4244xxxyyy.
E.g. for my local network 44.137.40.0/22 the AS will be 4244137040.
When areas of AS allocation are larger, an arbitrary subnet (e.g. the first) within that area can
be used to derive the AS number.
Alternatively, a national allocation system can be set up to manage the range available for a
country or state when local operators like to do so, and use registered AS numbers from 000-999
within the range derived from the /16 address.
E.g. the Netherlands has 44.137.0.0/16, so we can use the 1000-number AS range of
4244137000-4244137999 and subdivide it the way we like.
There may be a slight chance that some very old equipment would not support 32-bit AS numbers,
but the popular MikroTik, Ubiquiti and Linux(quagga) routers have no issue at all, and there is
some interoperability with peers running the older version.
I'd like to hear the opinions on this and possible enhancements/modifications.
Rob