User Programmable Virtualized Networks 12Robert J. Meijer, 1Rudolf J. Strijkers, 1Leon Gommans, 1Cees de Laat 1University of Amsterdam, Amsterdam, The Netherlands, 2TNO ICT, Delft, The Netherlands, rmeijer@science.uva.nl, rjstrijk@science.uva.nl, lgommans@science.uva.nl, delaat@science.uva.nl Abstract Abstract—This paper introduces the concept of a User Programmable Virtualized Network, which allows networks to deliver application specific services using network element components that developers can program as part of a users application. The use of special tokens in data or control packets is the basis of a practical, yet powerful security and AAA framework. This framework allows for implementations with a low footprint that can operate in a multi domain network operator environment. We demonstrate the ease with which one can build applications and address networking problems as they appear for example in sensor networks. 1. Introduction The concepts defined in the OSI model for the interaction between networks, end systems and their applications, are widely accepted [1]. International telecommunication infrastructures and the Internet are based on these concepts. Because details like network topology are irrelevant to most applications, OSI considers only end-to-end transport services. What if network providers cannot understand all of your network service demands anymore? What if the network cannot be over-provisioned due to the involved costs? If one detects that an IP router will fail shortly, how can we route a VoIP stream over an alternate path before the router actually fails and before the users notice anything? Do video streams of a burning car have priority over those of collided cars not far away in a heavily congested network? In such cases, there is a need to tune the network service to the demands of the users and their application programs; one has to facilitate application specific networking. Neither the set of Internet protocols, nor a network management system (NMS) provides practical control interfaces to individual network nodes. The services of TCP and UDP are often used trough socket APIs. Socket APIs however, hide most of the network details
such as topology. In theory, using the NMS would be one way for the application programmer to discover and possibly control network elements, such as Cisco’s Active Networks Abstraction [2]. The span of control of an NMS however, is typically restricted to a single network operator domain. Furthermore, NMSs are designed to support operators and not end user programs. Moreover, only operators, not end users, are allowed to use the NMS. The concept of programmable networks is sufficiently well known to create concepts and technologies that support application specific networking [3]. The concepts differ in how applications interface with network nodes. Basically there are three variants: agents, active messages (also known as active networks) and remote method invocations (RMI) [4]. In short, agents are programs that travel from node to node, active messages are network packets extended with application code and webservices are a great example of RMI. The IETF ForCES working group basically standardizes common elements in IP routers [5]. One of the benefits is that elements may be changed or added and combined with web and Grid services [6][7]. ForCES does not have a security concept that is practical in a multi domain network (see Section 2.3). Currently, years of developments in programmable networks have lead to complex frameworks with corresponding complex technologies. This prevented the emergence of killer applications and market impact [8]. Sensor networks are frequently designed to operate in a very dynamic context, in which sudden environmental changes may cause parts of the network to become isolated. This has inspired the ad-hoc networking concept, where a system of identically programmed sensors collectively supports a telecommunication service amongst themselves [9][10]. Research, however, is predominantly focused on topics as autonomy and self- organization of sensor systems [9]. Little, if any, attention is given to the interaction between end-user applications and the sensor network and to the fact that in realistic situations sensor networks belong to multiple organizations.