Current Projects

7DS Resource sharing in wireless networks [Published Papers]
7DS is a disconnected wireless peer-to-peer network with the goal of information dissemination and resource sharing among devices in the network. 7DS exploits node mobility to increase data availability. Data can propagate from the Internet to mobile users and vice versa, offering high-latency versions of the web and email.

ADS Application and Desktop Sharing [Published Papers]
The aim of this project is to built an application and desktop sharing platform which is efficient, reliable, operating system independent, scales well, supports all applications and features true application sharing.

AINTSIP Ain't SIP: Automated Interoperability Tests for SIP [Published Papers]
Ain't SIP is an effort to create a publicly available automated test infrastructure to identify, test and document SIP interoperability issues.

BonAHA Library for P2P applications in disconnected opportunistic networks [Published Papers]
BonAHA is a library that can be used for easily building rich P2P applications that can operate in a regular always-on network, an ad-hoc wireless network or even in a disconnected scenario.

CINEMA Columbia InterNet Extensible Multimedia Architecture [Published Papers]
CINEMA is a full-featured VoIP and multimedia collaboration system, including a SIP proxy server, VoiceXML server, conference server, SIP-H.323 protocol gateway, and unified messaging server. The proxy server is designed to be highly scalable, and programmable using SIP servlets, sip-cgi and CPL.

CureSPIT Controlling Unsolicited Requests and SPIT calls [Published Papers]
The aim of this project is to reduce unsolicited incoming communication attempts, especially incoming SPIT (Spam Internet Telephony) calls, by enhanced labeling mechanisms. Our labeling mechanisms enable recipients to determine whether they have contacted the originators before through other means such as emails, calls, web transactions, or social network services.

DotSlash Web hotspot rescue system [Published Papers]
The DotSlash project aims to develop effective overload protection mechanisms for busy Web servers. Highly bursty Web requests may overwhelm a Web site and seriously degrade its service quality. This problem is often referred to as Slashdot effect. DotSlash automatically adds rescue servers to a web site during overload, without administrator intervention. In the current prototype, DotSlash supports both static web pages as well as web applications built on LAMP (Linux, Apache, MySQL, PHP).

DYSWIS Do You See What I See [Published Papers]
DYSWIS (Do you see what I see) is an end-to-end network fault diagnosis system. The objective of this project is building a distributed, intelligent and user-friendly network fault diagnosis system. This system detects different types of network faults automatically and starts diagnosing. To diagnose the faults, end nodes collaborate each other to get various information from other sides of network. For example, they might request another node to try same transaction which caused the fault to see whether same fault occurs at the node.

FAA Improving training for air traffic controllers [Published Papers]
This multi-year research and development effort, funded by the U.S. Federal Aviation Academy (FAA), turned a proprietary hard-wired analog communication system of the FAA Academy into a configurable, standards-based VoIP system that runs on their existing data network. Operating as a mid-level fidelity simulator, it trains air traffic controllers in radio operations, allowing students and instructors to work through scripted scenarios. The FAA Academy is successfully using this VoIP system in six training rooms in their Oklahoma facility to train future air traffic controllers, both from the United States and abroad.

GloServ Global service discovery [Published Papers]
GloServ is a global service discovery architecture which uses the OWL ontology to classify services as well as map them onto nodes in a hybrid hierarchical and peer-to-peer network.

MassFilter Filtering gigabits of voice traffic [Published Papers]
We are developing techniques for evaluating the performance of large-scale firewalls for VoIP. These firewalls need to handle tens of thousands of concurrent calls, without leaking unauthorized packets or cutting of voice communications.

MobApp Personal, service and session mobility for multimedia applications [Published Papers]
Beyond terminal mobility, next-generation mobile systems need to support application-layer mobility that allows a single user to be reachable under one identifier even when using multiple devices (personal mobility), to change devices while maintaining configuration information and to move active sessions, possibly as components, among mobile and stationary devices.

NetServ Enabling service virtualization at the Internet core [Published Papers]
To address the limitations of services in the current Internet, this work presents a clean slate Internet architecture, called NetServ, based on the concepts of service virtualization. NetServ strives to break up the functions provided by Internet services and to make these functionalities available as modular building blocks for network services.

NG911 Next-generation emergency calling for VoIP [Published Papers]
The NG911 project is developing a prototype for a next-generation emergency calling system suitable for VoIP. The system incorporates location determination, call routing and public safety answering point (PSAP) infrastructure.

NSIS Next steps in signaling [Published Papers]
As part of the IETF NSIS working group, we are contributing to a generic IP signaling protocol that separates the transport of the signaling from the application signaling (e.g., QoS, NAT traversal). Our current work focus on the NSIS transport layer protocol called General Internet Messaging Protocol for Signaling (GIMPS), NSIS operation over IP tunnels, and NSIS interaction with IP mobility and route change.

OpenVoIP OpenVoIP [Published Papers]
OpenVoIP is an open peer-to-peer VoIP system deployed on PlanetLab. Unlike OpenDHT, where it was only possible to put/get the data, we allow non-PlanetLab nodes to become part of our overlay. OpenVoIP provides NAT traversal services using STUN, TURN, and ICE. OpenVoIP also provides a GoogleMap Interface to check the health of the system.

PBS Signaling architecture for network traffic authorization [Published Papers]
Permission-Based Sending (PBS) is a signaling architecture for network traffic authorization. This architecture aims to prevent Denial-of-Service (DoS) attacks and other forms of unauthorized traffic. PBS exploits control plane signaling protocol architecture (NSIS Signaling Layer Protocol) and secure authorization (permission) for resource control.

SIMPLEstone Performance measurements for SIMPLE presence [Published Papers]
SIMPLEstone is a benchmark for presence systems based on the Session Initiation Protocol (SIP), commonly known as SIMPLE.

sipc SIP user agent [Published Papers]
sipc is a SIP user agent that can be used for Internet telephony calls. It supports a range of media types, such as audio, video, text, white board, desktop sharing, and can be extended easily to additional media types. In addition to multimedia communications, sipc supports presence indication, instant messaging, networked appliance control, real-time multimedia streaming (RTSP), networked resource discovery (SLP), third-party call control, Internet TV (SAP), location sensing, and emergency call handling. It can also interact with email clients and web browsers.

SIPerf The Impact of TLS on SIP Server Performance [Published Papers]
Despite a growing interest in securing Session Initiation Protocol (SIP) signaling, actual large scale deployment of SIP over Transport Layer Security has not yet occurred. One important reason is that VoIP providers will be hesitant to deploy TLS until they understand its impact on resource provisioning and capacity planning required. We evaluate the cost of TLS on SIP server performance experimentally using a testbed with OpenSIPS, OpenSSL, and Linux running on an Intel-based server.

SIPOL SIP Server Overload Control [Published Papers]
The Session Initiation Protocol (SIP) is a core signaling protocol for managing media sessions in the next generation networks. With the wide-spread deployment of SIP, people have come to recognize the congestion collapse behavior of SIP servers under overload conditions. As part of the Internet Engineering Task Force (IETF) design team, we are investigating effective SIP server overload control mechanisms.

VoIPeering VoIP Peering and ENUM [Published Papers]
VoIP peering enables calls originated or terminated at existing VoIP clouds to bypass the traditional PSTN networks as much as possible. It brings in a number of benefits for service providers and enterprises such as service flexibility, cost savings, quality improvement and so on. ENUM is a central protocol in VoIP peering which translates E.164 phone numbers to Internet Resource Identifiers (URIs). We evaluated performance of popular server software acting as ENUM servers. We also investigated privacy issues for service providers participating in VoIP peering.

VoWi Voice over WiFi [Published Papers]
Supporting VoIP on WiFi (802.11) networks poses a number of challenges. The project is developing a new MAC protocol (dynamic PCF), fast layer-2 hand-off mechanisms and new duplicate address detection (DAD) algorithms that support a significantly larger number of sessions and drastically reduce the hand-off delays both for layer-2 and layer-3 hand-offs.

z2z Zeroconf-to-Zeroconf Toolkit [Published Papers]
Zeroconf-to-Zeroconf Toolkit (z2z) extends the reach of the Zeroconf service discovery (aka Bonjour by Apple) beyond local link. Yes, this means that it lets you access your iTunes music shares across the Internet.

Completed Projects