I am a PhD student in the Network Research Group and Media Futures Research Group of the Department of Computer Science at the University College London. My supervisors are Dr. Shi Zhou and Dr. Jun Wang. I am funded by EPSRC and I am working on the analysis of the dynamics behind the evolution of the Internet topology at the Autonomous Systems level.

I have received my BSc in Computer Science from the University of Piraeus, Greece and I was awarded with distinction the MSc in Data Communications, Networks and Distributed Systems from UCL (now renamed to MSc in Networked Computer Systems).

Interdomain Routing

The uncoordinated growth and dynamic nature of the Internet have resulted in a highly complex network that makes difficult the design of new protocols and economic policies with predictable behavior and impact. Mathematical models that explain the dynamics behind the evolution of the Internet topology can become a valuable tool for researchers, allowing them to understand various macroscopic properties of the Internet and perform simulations to test and tune their proposals.

My research primarily focuses on the Autonomous System abstraction of the Internet topology, where each node is an Autonomous System (AS) – a collection of routers that share the same IP prefixes and are administered by the same network operator - and each link is a contractual relationship between two ASes that agree to exchange traffic under a specific business model. Routing in the AS graph is called inter-domain routing while routing whithin an AS is called intra-domain routing. The AS connectivity has important implications in many research areas, including inter-domain routing, security, QoS and P2P overlay networks.

The de-facto protocol for inter-domain routing is the Border Gateway Protocol (BGP). BGP calculates the AS paths based on locally configured BGP policies that are heavily affected by the business relationships between the connected ASes. One of the primary issues I try to tackle is the lack of correct or accurate data for the AS relationship and the derived BGP policies. More reliable policy data can allow researchers to conduct realistic BGP simulations and enable operators to take more informed decisions.

2011

• Vasileios Giotsas, Shi Zhou: Detecting and assessing the hybrid IPv4/IPv6 AS relationships (poster). SIGCOMM 2011: 424-425
• Vasileios Giotsas, Shi Zhou: Inferring Internet AS Relationships Based on BGP Routing Policies, arXiv:1106.2417v3 [cs.NI]

2009

• Stefanos Nikolidakis, Vasileios Giotsas, Dimitrios Vergados, Christos Douligeris: A mobile healthcare system using IMS and the HL7 framework, ANCS'09: Symposium on Architecture for Networking and Communications Systems, p.187-188, (2009)

2008

• Alexandru Radoi, Antonios Ntoulas, Foivos Demertzis, George Constantinides, Vasileios Giotsas: TRAP: Tainting Rapid Analysis Platform. Master Thesis

Teaching assistant for: Networks and Graphics (COMP2011)

Tutor for: Database Systems (INST2005)

Tutor for: Web Technologies

Lab Instructor for: Computer Security 1 (COMPGA01)