From the Editor - The Internet Protocol Journal - Volume 9, Number 1

Autonomous Systems Numbers (ASNs) play an important role in the routing architecture of the Internet. An Autonomous System (AS) is, according to RFC 4271, â€Å“... a set of routers under a single technical administration, using an interior gateway protocol (IGP) and common metrics to determine how to route packets within the AS, and using an inter-AS routing protocol to determine how to route packets to other ASs.â€ï¿½ AS numbers are—like IP addresses—a finite resource, and predictions exist for when the AS number pool will be depleted. In our first article, Geoff Huston explains how ASNs work, and introduces us to the 4-byte ASN scheme that will allow for future growth beyond the currently predicted depletion date.

Our second article looks at another aspect of Internet routing and addressing—the IPv4 number space itself. Designers and operators of internets are often required to perform various address calculations in order to properly configure their networks. Russ White takes us through several exercises and introduces some â€Å“tricks of the tradeâ€ï¿½ to make such calculations easier.

Our articles on spam in the last issue of IPJ prompted some feedback from our readers, and promises of more articles from other authors. This problem space clearly has more than a single solution. We look forward to bringing you more coverage of this topic in future editions.

The second issue of the IETF Journal, published by the Internet Society, is now available. Some people have asked me if I think of this new journal as a â€Å“competitorâ€ï¿½ to IPJ. I am happy to say that the IETF Journal is very much complementary to IPJ and covers important news from the IETF that we hope our readers will find interesting. You can access the IETF Journal by visiting:

The IPJ Reader Survey will soon close. We are grateful to the many readers who took the time to tell us about their reading habits, ideas for future articles, and other suggestions. Of course, we always welcome your feedback on any aspect of IPJ. Just drop us a line via e-mail to:

—Ole J. Jacobsen, Editor and Publisher