The effects of Active Queue Management and Explicit Congestion Notiﬁcation on DNS Trafﬁc
Stefanos Harhalakis, Nikolaos Samaras, Vasileios Vitsas, “The effects of Active Queue Management and Explicit Congestion Notiﬁcation on DNS Trafﬁc” IEEE Symposium on Computers and Communications, pp.906-911, July 2011
Abstract: Active Queue Management (AQM) and Explicit Congestion Notiﬁcation (ECN) are two methods that attempt to alleviate the problems of FIFO queues and of packet drops for congestion indication respectively. Random Early Detection (RED) is the most popular AQM method. The Domain Naming System (DNS) protocol is a core Internet protocol with very high impact on user experience and overall network functionality. This paper presents experimental results that show an inefﬁciency of RED that results in degraded performance of the DNS protocol when compared with FIFO queues. The results that are presented show 8 to 50 percentage points drop of DNS efﬁciency depending on network conditions.
Reconsidering the usage of standalone packets for congestion indication
Stefanos Harhalakis, Nikolaos Samaras, Vasileios Vitsas, “Reconsidering the usage of standalone packets for congestion indication” Electronics Letters, vol. 46, no. 11, pp.765-766, may 2010
Abstract: With the introduction of active queue management and explicit congestion notification, Internet router queues have become an active part of congestion control. It is pointed out that data flows with one packet per direction (standalone packets) are not allowed to take advantage of explicit congestion notification (ECN), which means that they will experience unprivileged handling by intermediate routers. A proposal is presented for reducing the unintended drops of standalone packets by active queue management when it is combined with ECN. The method is backwards compatible and can be deployed incrementally without introducing security risks. The method is simulated on domain name system traffic showing significant improvement of user experience.
Exploiting the Congestion Control Behavior of the Transmission Control Protocol
Stefanos Harhalakis, Nikolaos Samaras, Vasileios Vitsas, “Exploiting the Congestion Control Behavior of the Transmission Control Protocol” BCI, pp.203-208, 2009.
Abstract: This paper presents a realistic method for exploiting an already known insecurity of the Congestion Control behavior of the Transmission Control Protocol that was originally pointed out in 1999 and that affects all known TCP implementations. This insecurity exploits the fundamental assumption of TCP that the communicating remote end is trustworthy and is behaving correctly. We developed a methodology and an algorithm which we used to attack a web server and deceive it in transmitting with a constant rate of 900 Mbits per second. During the attack the server was incapable of reacting to the network congestion it caused.
An Improvement to OSPF for avoiding overloaded nodes
Stefanos Harhalakis, Nikolaos Samaras, “An Improvement to OSPF for avoiding overloaded nodes” Master Thesis, Sep 2006
Abstract: This document examines a new subject in the areas of routing and computer networks. We begin with a comprehensive introduction to networks, TCP/IP and Internet technologies. Next we examine in more detail the IP routing and particularly the OSPF routing algorithm. We discuss in depth the routing procedure analyzing the problems that occur when a router becomes overloaded and can no longer handle the network load. An algorithm is being proposed as a solution to this problem. It is based on the Link State routing protocols operation and tries to ﬁnd and use alternative routes to route network traﬃc without creating routing loops. This leads to a decrease of the overloaded routers’ load and gives a boost to network performance. Detailed examples of the algorithm operation are being presented. The document also includes the complete pseudocode of the algorithm which was implemented in C/C++. The implementation was tested against more than 800.000 graphs and it resulted in the experimental proof of the algorithm functionality.
Stefanos Harhalakis, Nikolaos Samaras, Eleni Fragiadaki, “An extension to OSPF algorithm for avoiding overloaded nodes” Σχεδίαση Λειτουργιών, Ανάκτηση Πληροφοριών και Διαχείριση Γνώσης, pp.995-1006, June 2006
Stefanos Harhalakis, Nikolaos Samaras, Eleni Fragiadaki, “An improved method for experimental evaluations of TCP Congestion Control Algorithms” Book of abstracts, pp.30-31, Sep 2007
Stefanos Harhalakis, Nikolaos Samaras, Eleni Fragiadaki, “An extended evaluation of a collection of TCP Congestion Control Algorithms” Book of abstracts, pp.127-128, Sep 2007
Alexandros Katsaros, Stefanos Harhalakis, “Multiprotocol Label Switching”, 2009 (Download)
Alexandros Ieronymos, Stefanos Harhalakis, “Δημιουργία Client-Server εφαρμογής για on-demand μεταφορά αρχείων με χρήση Multicast”, Nov 2010 (Download)