A Framework for Rapid Development and Portable Execution of Packet-Handling Applications

This paper presents a framework that enables the execution of packet-handling applications (such as sniffers, firewalls, intrusion detectors, etc.) on different hardware platforms. This framework is centered on the NetVM - a novel, portable, and efficient virtual processor targeted for packet-based processing - and the NetPDL - a language dissociating applications from protocol specifications. In addition, a high-level programming language that enables rapid development of packet-based applications is presented

Array Convolutional Low-Density Parity-Check Codes

This paper presents a design technique for obtaining regular time-invariant low-density parity-check convolutional (RTI-LDPCC) codes with low complexity and good performance. We start from previous approaches which unwrap a low-density parity-check (LDPC) block code into an RTI-LDPCC code, and we obtain a new method to design RTI-LDPCC codes with better performance and shorter constraint length. Differently from previous techniques, we start the design from an array LDPC block code. We show that, for codes with high rate, a performance gain and a reduction in the constraint length are achieved with respect to previous proposals. Additionally, an increase in the minimum distance is observed.Comment: 4 pages, 2 figures, accepted for publication in IEEE Communications Letter

Modularità applicata all'elaborazione di pacchetti di rete: il linguaggio NetPDL

Questo articolo presenta NetPDL, un linguaggio basato su XML che permette di descrivere il formato delle intestazioni e l'imbustamento dei protocolli di rete e la sua implementazione nella libreria NetBe

Comparing the Efficiency of IP and ATM Telephony

Circuit switching, suited to providing real-time services due to the low and fixed switching delay, is not cost effective for building integrated services networks bursty data traffic because it is based on static allocation of resources which is not efficient with bursty data traffic. Moreover, since current circuit switching technologies handle flows at rates which are integer multiples of 64 kb/s, low bit rate voice encoding cannot be taken advantage of without aggregating multiple phone calls on a single channel. This work explores the real-time efficiency of IP telephony, i.e. the volume of voice traffic with deterministically guaranteed quality related to the amount of network resources used. IP and ATM are taken into consideration as packet switching technology for carrying compressed voice and it is compared to circuit switching carrying PCM (64 Kb/s) encoded voice. ADPCM32 is the voice encoding scheme used throughout most of the paper. The impact of several network parameters, among which the number of hops traversed by a call, on the real-time efficiency is studie

Progressive Differences Convolutional Low-Density Parity-Check Codes

We present a new family of low-density parity-check (LDPC) convolutional codes that can be designed using ordered sets of progressive differences. We study their properties and define a subset of codes in this class that have some desirable features, such as fixed minimum distance and Tanner graphs without short cycles. The design approach we propose ensures that these properties are guaranteed independently of the code rate. This makes these codes of interest in many practical applications, particularly when high rate codes are needed for saving bandwidth. We provide some examples of coded transmission schemes exploiting this new class of codes.Comment: 8 pages, 2 figures. Accepted for publication in IEEE Communications Letters. Copyright transferred to IEE

Time-Invariant Spatially Coupled Low-Density Parity-Check Codes with Small Constraint Length

We consider a special family of SC-LDPC codes, that is, time-invariant LDPCC codes, which are known in the literature for a long time. Codes of this kind are usually designed by starting from QC block codes, and applying suitable unwrapping procedures. We show that, by directly designing the LDPCC code syndrome former matrix without the constraints of the underlying QC block code, it is possible to achieve smaller constraint lengths with respect to the best solutions available in the literature. We also find theoretical lower bounds on the syndrome former constraint length for codes with a specified minimum length of the local cycles in their Tanner graphs. For this purpose, we exploit a new approach based on a numerical representation of the syndrome former matrix, which generalizes over a technique we already used to study a special subclass of the codes here considered.Comment: 5 pages, 4 figures, to be presented at IEEE BlackSeaCom 201

ALEX: Improving SIP Support in Systems with Multiple Network Addresses

The successful and increasingly adopted session initiation protocol (SIP) does not adequately support hosts with multiple network addresses, such as dual-stack (IPv4-IPv6) or IPv6 multi-homed devices. This paper presents the Address List Extension (ALEX) to SIP that adds effective support to systems with multiple addresses, such as dual-stack hosts or multi-homed IPv6 hosts. ALEX enables IPv6 transport to be used for SIP messages, as well as for communication sessions between SIP user agents (UAs), whenever possible and without compromising compatibility with ALEX-unaware UAs and SIP servers