An Autonomous System (AS) is a group of IP address networks managed by one or more network operators having a clear and unique routing policy. Each Autonomous System (AS) has an associated number that is used as the Autonomous System's identifier when exchanging external routing information. Exterior routing protocols, such as BGP, are used for exchanging routing information among Autonomous Systems.
The term "Autonomous System" is frequently misinterpreted as merely a convenient way to refer to a group networks that are under the same management. However, if there is more than one routing policy in the group, then more than one AS is necessary. On the other hand, if the group of networks has the same policy as the other groups, they fall within the same AS regardless of their management structure. Thus, by definition, all networks that make up an Autonomous System share the same routing policy.
In order to simplify global routing tables, a new Autonomous System Number (ASN) should only be assigned when a new routing policy is necessary.
Sharing the same ASN among a group of networks that are not under the same management will require additional coordination among network administrators and, in some cases, will require redesigning the network to a certain degree. However, this is probably the only way to implement the desired routing policy
LACNIC shall allocate Autonomous System Numbers to those organizations that meet the following requirements:
It is the obligation of the organization receiving an Autonomous System Number from LACNIC to maintain updated records of postal addresses and points of contact.
LACNIC's WHOIS system allows representing up to three different points of contact, namely:
owner-c, which represents the administrative contact of the organization to which the ASN was assigned;
routing-c, contact who, by means of the IP and ASN administration system, may register the routing policies adopted by the Autonomous System;
abuse-c, security contact (Abuse Contact).
16-bit AS numbers were defined in RFC 1930 and integers ranging from 0 to 65535 will be used for their identification. Likewise, 32-bit AS numbers were defined by RFC 4893 and integers ranging from 0 to 4294967295 will be used for their identification. In both cases the "asplain" decimal value representation defined in RFC 5396 will be used.
Consequently, the following terminology will be adopted to refer to 16-bit and 32-bit ASNs:
There shall be three phases for ASN allocation on the part of LACNIC: