The Internet Protocol Journal - Volume 4, Number 2

A user of a laptop computer "on the road" typically connects to the Internet in one of two ways. The oldest, and most common method, is to dial into an ISP's network and obtain an IP address using the Point-to-Point Protocol (PPP). The other method involves attaching the laptop to a local network (usually via Ethernet) and obtaining an IP address through the Dynamic Host Configuration Protocol (DHCP). The "local network" could be anything from the high-speed connection provided in some hotels, to an enterprise network at some corporation or other institution. In all cases, the IP address is fixed for the duration of the network session, and the routing of packets from the laptop back to its "home" network remains a relatively straight-forward task (ignoring NATs, firewalls and other complexities for the moment). Suppose however, the mobile computer is using a wireless connection and traveling between several networks over a short period of time. In this scenario one would still like to maintain network connectivity in a seamless manner. The IETF has been working on Mobile IP to address this problem. Mobile IP is the subject of our first article by Bill Stallings.

The art of cryptography is certainly not new, but its use in computer-communications is a more recent phenomena. The Data Encryption Standard (DES) has been widely used since it was standardized in 1977. The strength of a particular encryption scheme depends on the key length and the sophistication of the mathematics involved in transforming the so-called cleartext to the encrypted form. As computers have become more powerful it is now possible to systematically "guess" the 56-bit DES keys in a matter of hours, thus a new encryption standard is needed. This new standard, known as the Advanced Encryption Standard (AES), is described by Edgar Danielyan.

Many aspects of computer networking can be described as "controversial," that is, there are strongly held opinions about a particular technology or its use. In this issue we begin a new series of articles labelled "Opinion," hoping to bring out some of the different views held by members of the networking community. We hope you will take issue with some of these columns and send us your own opinion piece. We begin the series with an article by Geoff Huston entitled "The Middleware Muddle." Let us know what you think by sending your comments to ipj@cisco.com