IP/ASN Addressing Information


#1

#WACAN IP Addressing Scheme

WACAN has allocated itself a block of IP space inside the 10.32/11 range, starting at 10.48/16 (allocated to WA as per: http://www.air-stream.org/asipdb)

Each location we have infrastructure in is allocated a single /16 inside this range, with Perth Metro being 10.48.0.0/16.

To allocate IP addressing space in a programatic fashion, we find a central point in that region, then using that point-- divide the region into four areas (typically North, East, South, West). The /16 is then sliced into four equal /18s and allocated to each region.

Using Perth Metro as an example:

  • 10.48.0.0/18 -> Perth Metro - Northern
  • 10.48.64.0/18 -> Perth Metro - Eastern
  • 10.48.128.0/18 -> Perth Metro - Southern
  • 10.48.192.0/18 -> Perth Metro - Western

This subnetting scheme allows us to evenly allocate IP space to each region, as well as providing an ‘at a glance’ way of establishing in which area each node is in.

If a region is deemed to not require a full /16, we can allocate /17s if required, shrinking the area allocations respectively.

ASN Allocation

In order to avoid conflicts with established networks-- whilst maintaining a clean, clear and ultimately rememberable way of allocating ASNs, We’ll be using 4 byte (32bit) ASNs from the range allocated for private use.

The 4-byte (32-bit) ASN private range is 4,200,000,000 to 4,294,967,294, inclusive.

The ASN will be allocated at the same time as the primary subnet for the node and we’ll use that subnet to construct the ASN.

To construct the ASN you simply pad the subnet out with zero’s (10.48.0.0/24 becomes 010.048.000.000), remove the leading 0 and the last octet… Once you have that number (10.48.0.0/24 -> 10048000), you prepend 42 to the beginning.

Examples:
10.48.128.0/24 (010.048.128.000/24) = 4210048128
10.49.231.0/24 (010.049.231.000/24) = 4210049231
10.50.253.0/24 (010.050.253.000/24) = 4210050253

This method will allow us to easily identify what subnet the ASN is assigned to, there will not be any conflicts, and all of the ASN’s in this design fit within the private range for 4-byte ASNs