Supporting group communication on a lightweight programmable network.

摘要

The current Internet architecture lacks adequate support for group communication services. Multicast offers a best-effort one-to-many service, but it does not meet the needs of applications that wish to control group membership, define the distribution tree, monitor congestion, and so on. Our research investigates a new way to extend and enhance router services. The extensions are generic and can be used by a wide range of network services. We show how the extended router functionalities can improve group communication.; We propose a programmable network framework that supports two new building-block services at routers: (1) Lightweight Packet Processing (LWP) modules that provide applications the ability to enable processing functions that modify router behaviors in a very limited way; and (2) Ephemeral State Processing (ESP), a bounded-lifetime memory store at routers that allows end systems to discover network information using extremely lightweight distributed computations. Given the additional, but limited, control of network functions, end systems can learn information about the network and enable processing inside the network as needed. We show that LWP and ESP present a scalable way to extend network services while maintaining the simple and robust characteristics of the Internet architecture.; We demonstrate the utility of our approach by showing how to design end-system controlled multicast services to support scalable group communications on the ESP/LWP framework. End systems can control the multicast implementation, using ESP to pinpoint branch-point locations on the multicast tree, and LWP to enable duplication processing at the appropriate locations to copy data to multicast receivers. Our design minimizes the number of routers that must maintain multicast state, resulting in less total state than conventional IP multicast. We also show that the ESP/LWP framework enables end systems to implement a receiver-driven layered multicast service that provides efficient data delivery and accurate congestion control. We demonstrate the viability of LWP and ESP services through prototype implementations using the Intel IXP 1200 network processor.