Introducing New Internet Services : Why

Active networks permit applications to inject programs into the nodes of local and, more importantly, wide area networks. This supports faster service innovation by making it easier to deploy new network services. In this paper, we discuss both the potential impact of active network services on applications and how such services can be built and deployed. We explore the impact by suggesting sample uses and arguing how such uses would improve application performance. We explore the design of active networks by presenting a novel architecture, ants, that adds extensibility at the network layer and allows for incremental deployment of active nodes within the Internet. In doing so, ants tackles the challenges of ensuring that the exibility ooered by active networks does not adversely impact performance or security. Finally, we demonstrate how a new network service may be expressed in ants. 1 Why Active Networks? The pace of innovation in networked applications is unrelenting. New applications continue to emerge rapidly and often beneet from new network services that better accommodate their modes of use. In this paper, we address the questions of why and how to deploy such new services. We begin by observing that while it is possible to deploy new network services at end-systems (e.g., as overlays), implementing them at nodes interior to the network or at the network layer often ooers better functionality and performance. This observation is supported by a number of ad hoc eeorts to exploit such functionality: Multimedia applications (such as videoconferencing and Internet telephony) beneet from real-time and multicast services. For example, RSVP 3] reserves fdjw, bandwidth to ensure that time-sensitive data is delivered in a timely fashion, and IP Multicast 4] reduces the bandwidth needed to communicate from one sender to multiple receivers. In the case of RSVP, bandwidth reservation functionality cannot be provided eeectively above the network layer. In the case of multicast, excess bandwidth and latency costs are incurred when an overlay is used and its topology does not match the underlying topology, as was problematic in the early MBONE. Laptops beneet from host mobility and transport services optimized for wireless transmission. For example , Mobile IP 18] allows a laptop to be reached at diierent sites without the need to reconngure address information, and Snoop-TCP 1] compensates for the fact that the congestion control mechanisms of TCP were not designed for lossy media. Mobile IP is by deenition a network-level …