16-bit ASNs still available in the LACNIC Service Region

31/08/2016

Even though the IANA (Internet Assigned Numbers Authority) announced the exhaustion of the central pool of 16-bit ASNs (Autonomous System Numbers) in August, LACNIC still has 16-bit ASNs in stock for its Latin American and Caribbean members, reported Sergio Rojas, Head of LACNIC’s Registration Services Department.

The policies adopted by the community for managing its number resources have allowed LACNIC to continue to have both types of existing ASNs: 16-bit and 32-bit.

An ASN is a number used to group IP networks having their own independent routing policy: they manage their own traffic with other autonomous systems on the Internet. “If we think about IP addresses as a house’s street name and number, the ASN is the post code for the area,” explained Rojas.

Until 2007, autonomous system numbers were defined by a 16-bit integer, but this allowed assigning a limited amount of ASNs. As demand increased, more autonomous system numbers were needed. This led to the creation of 32-bit autonomous systems.

Since 2011, LACNIC assigns 32-bit ASNs to its members by default. However, in case of incompatibility with a member’s equipment, LACNIC may authorize a swap of this 32-bit ASN for a 16-bit ASN.

“There is no advantage or disadvantage in using one (16-bit ASN) or the other (32-bit ASN). It’s simply a matter of equipment compatibility. Certain older devices do not support 32-bit ASNs,” added Rojas.

Current equipment trends mark that the use of 32-bit ASNs will be the norm. “Assignment behavior in the LACNIC region shows that this protocol is being used without problems, as 32-bit ASNs are assigned by default,” noted the Head of LACNIC’s Registration Services Department. In the past twelve months, LACNIC has assigned 842 32-bit ASNs and 42 16-bit ASNs.