Sebastian Gunreben

Ethernet – A Survey on its Fields of Application

During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application fields requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal.

Enhanced Backwards Recursive Path Computation for Multi-area Wavelength Switched Optical Networks Under Wavelength Continuity Constraint

In the context of the future Internet, all-optical wavelength switched optical networks will play an important role in either evolutionary or revolutionary design paradigms. In any paradigm, dense wavelength domain multiplexing (DWDM) is the most cost-effective technology to increase bandwidth capacity. DWDM provides the basis for a core optical transport infrastructure supporting a wide range of heterogeneous services. However, such all-optical networks raise well-known challenges such as the wavelength continuity constraint (WCC). The WCC is hard to address in a multiarea scenario when provisioning an end-to-end lightpath owing to network topology hiding requirements and the limited exchange of information between areas. The Internet Engineering Task Force (IETF) is currently standardizing the path computation element (PCE) architecture, a good candidate to perform multidomain path computation. In such an architecture, the approach named backwards recursive path computation (BRPC), also under standardization at the IETF, aims at overcoming the limitations of the per-domain mechanism. However, although BRPC does provide end-to-end shortest paths, it fails to take into account the WCC, which is the main motivation for this work. We extend the BRPC algorithm and the companion PCE protocol in order to address the end-to-end WCC efficiently. We perform a quantitative comparative analysis of the different approaches, experimentally showing the improvements of the conceived solution, which has been evaluated in a GMPLS-controlled network of the ADRENALINE testbed.

Modeling and performance evaluation of iSCSI storage area networks over TCP/IP-based MAN and WAN networks

This paper provides a concise modeling and performance evaluation of the iSCSI storage area network (SAN) architecture and protocol. SANs play a key role in business continuity, enterprise-wide storage consolidation and disaster recovery strategies in which storage resources are most often distributed over many distant data center locations. In the future, SAN traffic will be transported over IP-based networks, e.g., enterprise virtual private networks, to benefit from converged networks and save cost. In these scenarios, the impact of end-to-end delay and QoS of broadband networks on SAN performance is critical and has to be well understood by IT departments when deploying IP-storage solutions and network operators when designing transport network services for SAN applications. In this context, we propose models for iSCSI write requests over TCP/IP networks, e.g., as used in asynchronous mirroring applications. In addition to the analysis for individual requests we present - to the best of our knowledge for the first time - the evaluation of an iSCSI session under a realistic request traffic model with and without interleaving. We analyze the throughput and total request write times for different network dimensions, i.e., round-trip times, and QoS levels, processing delays in the iSCSI layer as well as request characteristics

Assessment and performance evaluation of PCE-based inter-layer traffic engineering

Multi-layer (ML) and multi-domain networks require path computation elements (PCE) for constraint-based path calculation. In this paper we introduce and evaluate qualitatively as well as quantitatively the PCE scenarios newly proposed by the IETF for PCE-based inter-layer traffic engineering. Requirements on additional communication, on hardware and on optimality of path computation serve as the qualitative metrics in our comparison. The path setup delay is derived analytically and serves as the quantitative metric. We derive the results using simulations on the ML German reference network with 17 nodes and back-up our results by two different ML TE routing algorithms. We show that one single ML PCE performs best in the overall qualitatively and quantitatively comparison.

A quantitative evaluation of reordering in OBS networks and its impact on TCP performance

This paper presents a layered framework to measure the reordering introduced by contention resolution strategies in OBS networks. In particular, characterization is based on the reordering metrics proposed by the IETF IPPM WG. The obtained results are twofold. First, they quantify the impact of burst reordering on TCP throughput performance. Second, they give insight into solving burst reordering by well dimensioned buffers.

A multi-layer analysis of reordering in optical burst switched networks

In this paper we introduce a generic burst reordering model and analytically evaluate the reordering characteristic on both burst and packet layer in an OBS network. We apply the packet reordering definition and reordering metrics newly specified by IETF IPPM WG for precise characterization of burst and packet reordering. The results of this analysis give a first insight into the quantitative reordering characteristic on the burst and packet layers.

Multi-layer Analysis to Quantify the Impact of Optical Burst Reordering on TCP Performance

In this paper we provide a new methodology to quantify the impact of optical burst reordering in OBS networks on the TCP/IP end-to-end performance. We assume a multi-layer network stack consisting on TCP/IP on top of OBS. We propose a multi-layer analysis of burst and packet reordering that is realized by simulation. We apply the packet reordering definition of the IETF IPPM working group and use two different reorder metrics for precise characterization of reordering. We identify the key parameters in a burst and packet reordering scenario and point out TCP critical scenarios. We found that OBS only has an impact on the TCP performance in very dedicated scenarios.

An optical burst reordering model for time-based and random selection assembly strategies

Contention resolution schemes in optical burst switched networks (OBS) as well as contention avoidance schemes delay burst delivery and change the burst arrival sequence. The burst arrival sequence usually changes the packet arrival sequence and degrades the upper layer protocols performance, e.g., the throughput of the transmission control protocol (TCP). In this paper, we present and analyze a detailed burst reordering model for two widely applied burst assembly strategies: time-based and random selection. We apply the IETF reordering metrics and calculate explicitly three reordering metrics: the reordering ratio, the reordering extent metric and the TCP relevant metric. These metrics allow estimating the degree of reordering in a certain network scenario. They estimate the buffer space at the destination to resolve reordering and quantify the number of duplicate acknowledgements relevant for investigations on the transmission control protocol. We show that our model reflects the burst/packet reordering pattern of simulated OBS networks very well. Applying our model in a network emulation scenario, enables investigations on real protocol implementations in network emulation environments. It therefore serves as a substitute for extensive TCP over OBS network simulations with a focus on burst reordering.

An optical burst reordering model for a time-based burst assembly scheme

In optical burst switching networks, contention resolution schemes as well as contention avoidance schemes reduce the burst loss probability. These schemes delay the burst delivery and may change the burst arrival sequence. In this paper we present an analytic burst reordering model and derive analytically the impact of a time-based burst assembly scheme on the burst reordering pattern. Our results hold for a general network delay distribution. We apply the IETF WG IPPM reordering metrics and calculate explicitly three reordering metrics assuming a general burst delay distribution: the reordering degree, the extent metric for buffer dimensioning and the TCP relevant metric for TCP throughput estimation. We show that our analytic model represents a worst case reordering scenario, which enables studies on the upper layer protocol performance in OBS networks without excessive multi-layer simulations.

A Unified Model for Bandwidth Adaptation in Next Generation Transport Networks

In this paper we propose a unified model for dynamic bandwidth adaptation in future transport networks. It acts as an umbrella for both next generation SONET/SDH (NG-SONET/SDH) and even more general, networks with a GMPLS control plane. We adapt bandwidth in discrete steps by exploiting features of virtual concatenation and bundled links, respectively. Applying our model, we demonstrate its advantage in providing improved service quality in comparison to a scheduled provisioning scheme. We evaluate the adaptation granularity to provide a required quality of service for typical IP network traffic behavior in the access network. Furthermore we quantify in depth the impact of increasing access bandwidth at the network edge on signaling load in a transport network.