We describe the implementation of an OpenFlow Switch on the NetFPGA platform. OpenFlow is a way to deploy experimental or new protocols in networks that carry production traffic. An OpenFlow network consists of simple flow-based switches in the datapath, with a remote controller to manage several switches. In practice, OpenFlow is most often added as a feature to an existing Ethernet switch, IPv4 router or wireless access point. An OpenFlow-enabled device has an internal flow-table and a standardized interface to add and remove flow entries remotely.Our implementation of OpenFlow on the NetFPGA is one of several reference implementations we have implemented on different platforms. Our simple OpenFlow implementation is capable of running at line-rate and handling all the traffic that is going through the Stanford Electrical Engineering and Computer Science building. We compare our implementation's complexity to a basic IPv4 router implementation and a basic Ethernet learning switch implementation. We describe the OpenFlow deployment into the Stanford campus and the Internet2 backbone.

Identity-Based encryption is an asymmetric encryption system where identifiers such as email addresses, server names or phone numbers, can be used as public keys. Originally proposed by Adi Shamir in 1984, the first practical algorithm became available in 2001. Since then IBE has not only generated huge interest in academia, it has seen wide-scale adoption in industry, is used by hundreds of thousands of users and is in the process of being standardized by the IEEE.In this talk we will give an overview of the state of IBE, and reflect on what led to its rapid success. Unlike many encryption protocols, IBE is a new cryptographic paradigm that can not be built from existing encryption algorithms. As a new primitive, IBE directly solves some of the existing problems with classic public key systems. Specifically it enables the use of short-lived public keys, removes the overhead of certificate management and enables keys to be centrally managed. As a result IBE systems require less state and are much more lightweight and scalable than traditional PKI systems.In this talk we will give an overview over the IBE algorithms and standardization activities. We will describe a secure email systems based on IBE, and by examining the example of a live enterprise deployment of IBE discuss advantages and differences to traditional PKI.

All Internet routers contain buffers to hold packets during times of congestion. Today, the size of the buffers is determined by the dynamics of TCP's congestion control algorithm. In particular, the goal is to make sure that when a link is congested, it is busy 100% of the time; which is equivalent to making sure its buffer never goes empty. A widely used rule-of-thumb states that each link needs a buffer of size B = overlineRTT x C, where overlineRTT is the average round-trip time of a flow passing across the link, and C is the data rate of the link. For example, a 10Gb/s router linecard needs approximately 250ms x 10Gb/s = 2.5Gbits of buffers; and the amount of buffering grows linearly with the line-rate. Such large buffers are challenging for router manufacturers, who must use large, slow, off-chip DRAMs. And queueing delays can be long, have high variance, and may destabilize the congestion control algorithms. In this paper we argue that the rule-of-thumb (B = (overlineRTT x C) is now outdated and incorrect for backbone routers. This is because of the large number of flows (TCP connections) multiplexed together on a single backbone link. Using theory, simulation and experiments on a network of real routers, we show that a link with n flows requires no more than B = (overlineRTT x C) √n, for long-lived or short-lived TCP flows. The consequences on router design are enormous: A 2.5Gb/s link carrying 10,000 flows could reduce its buffers by 99% with negligible difference in throughput; and a 10Gb/s link carrying 50,000 flows requires only 10Mbits of buffering, which can easily be implemented using fast, on-chip SRAM.

We are facing a growing user demand for ubiquitous Internet access. As result, network ports and wireless LANs are becoming common in public spaces inside buildings such as lounges, conference rooms and lecture halls. This introduces the problem of protecting networks accessible through these public ports from unauthorized use. In this paper, we study the problem of access control through public network ports. We view this problem as a special case of the more general problem of access control for a service on a network. We present an access control model on which we base our solution. This model has three components: authentication, authorization, and access verification. We describe the design and implementation of a system that allows secure network access through public network ports and wireless LANs. The design requires no special hardware or custom client software, resulting in minimal deployment cost and maintenance overhead. The system has a user-friendly, Web-based interface, offers good security, and scales to a campus-sized community.

A new concept for constructing an intelligent mobile system is proposed. We describe reasons for the necessity of a new architecture for mobile systems in intelligent spaces. The intelligent spaces are room or area that are equipped with sensors, network and computers. The intelligent spaces are expected to be authentic future environment. If environment gets intelligence, it is not a distinct part of an intelligent mobile system any more and also the mobile system becomes a physical agent of the intelligent space. In this paper, we do some experiments to show what are possible for a mobile robot in an intelligent space.

Intelligent spaces are rooms or areas that are equipped with sensors such as microphones or cameras that enable them to perceive what is happening in them. In such spaces that have an intelligence of their own a world model no longer is something the robot has alone but a service offered by the information infrastructure of the space. In this article we show how such an intelligent space can generate a topological map for robots by looking at the movements of people in the room. We describe the stereo vision system that is capable of tracking the 3D movements of several humans in real time and give experimental results obtained in a real-world environment with several people.

Adaptive filters and image enhancement techniques have repeatedly been suggested to make feature extraction more robust. Few comparative analysis exists between competing techniques and even the existing ones evaluate only the effect of the filter on the image but not its effect on a feature extraction process. We present an experimental approach for the evaluation of low level vision system components in a system framework. Our method is applied to adaptive filters. By analyzing the system architecture we chose an evaluation level and derive the evaluation criteria and parameter control strategies. The results show that none of the tested techniques performs better than linear filters or the Canny edge detector.

Computer vision systems are today an important sensor for intelligent robotic systems. However, the design of a vision system that a robot can use as a fast and robust sensor in a complex, partially unknown and dynamic environment is still difficult. A main reason for this is that the parameters of vision systems are often adjusted by hand and remain static during the operation of the robot. In this paper we present a general architecture that adapts the the parameters of a segment based low-level vision system dynamically to increase its speed and robustness. Adaptation is done to a priori knowledge about the environment or to the sensor data itself. The architecture is implemented on a mobile robot using special hardware that allows real-time operation. Quantitative experimental data on its performance is given.

The exploration and mapping of unknown environments is on important task for the new generation of mobile service robots. These robots are supposed to operate in dynamic and changing environments together with humans and in interaction with other stationary or moving objects. This requires a high flexibility and adaptability of the sensor-system to changing environmental conditions. Sensors that are capable of providing the quality of information that is required for the described scenario are optical sensors like digital cameras and laserscanners. In this paper a sensor system and an architecture for active control of the sensors and adaptive processing of the perceived sensor data are developed for service applications and experimentally evaluated.