Henrik Wessing

Novel scheme for packet forwarding without header modifications in optical networks

We present a novel scheme for packet forwarding in optical packet-switched networks and we further demonstrate its good scalability through simulations. The scheme requires neither header modification nor any label distribution protocol, thus reducing component cost while simplifying network management.

Enhanced Signaling Scheme with Admission Control in the Hybrid Optical Wireless (HOW) Networks

The hybrid optical wireless (HOW) network has been viewed as a promising solution to meet the increasing user bandwidth and mobility demands. Due to the basic differences in the optical and wireless technologies, a challenging problem lies in the Media Access Control (MAC) protocol design so that it can support stringent Quality of Service (QoS) requirements. In this paper, we describe and evaluate a resource management framework designed for the HOW networks. There are two parts in the resource management framework The first part is the Enhanced MPCP (E-MPCP) scheme aiming at improving signaling ability between the optical and wireless networks. The second part is an Integrated Optical Wireless Admission Control (IOW-AC) scheme aiming at providing the integrated bandwidth allocation in the HOW networks. Our results show that the performances of the system in terms of throughput, delay and packet dropping probability depend on several factors. These factors include the frame duration, the traffic load and the total number of shared users. The results also highlight that our proposed system achieves significant improvements over the traditional approach in terms of user QoS guarantee and network resource utilization.

Protection for MPLS-TP multicast services

This paper proposes three innovative point-to-multipoint protection schemes to provide efficient and reliable MPLS Transport Profile multicast services, which is particularly relevant for the fast growing IPTV broadcast service. The three proposed protection schemes are all based on the interconnected rings structure, which is a widely deployed topology of legacy networks and has the natural ability to support resiliency. The first protection scheme extends the protection methods defined in the latest IETF draft standard to the interconnected rings structure. The second protection scheme introduces an adapted OAM function, which has the ability to monitor the multicast services status, such as configuration failures, software failures and performance degradation, to ensure the reliability of the whole branches and leaves of the multicast service. Furthermore, the interconnecting nodes of the rings make the protection switching decision, which releases the work to upgrade every node on the existing ring and thereby eases the MPLS Transport Profile network deployment. Instead of having one working path in one direction and the other direction being used as protection path, in the third protection scheme, the paths in both directions are used as working paths. When there is a failure, the two working paths protect each other, which increases the efficiency of the network resources. The traffic distribution on the ring is divided by these two separated working paths, which lowers the amount of affected entities when a failure occurs.

TCAM-based high speed Longest prefix matching with fast incremental table updates

This paper presents a new TCAM-based method for determining the Longest Prefix Match (LPM) in an IP routing table. The method is based on modifying the address encoder of the standard TCAM design to take the prefix lengths of the IP routing entries into account while performing multi-match resolution, thus allowing prefixes to be inserted in any random order. This enables full utilization of the TCAM address space while greatly simplifying the updating procedure as complex software sorting algorithms and extensive table modifications are avoided. The result is faster table updates and consequently a higher throughput of the network search engine, since the TCAM down time caused by incremental updates is eliminated. The LPM scheme is described in HDL for FPGA implementation and compared to an existing scheme for customized CAM circuits. The paper shows that the proposed scheme can process more packets per second, has less per-lookup power consumption and is easier to expand to larger routing tables than the existing implementation. The latency of the LPM operation is only log2 N clock cycles, where N is the maximum number of prefixes in the TCAM, and in a pipelined implementation the throughput of the system is one Longest Prefix Match lookup per clock cycle.

Automatic provisioning of end-to-end QoS into the home

Due to a growing number of high bandwidth applications today (such as HDTV), and an increasing amount of network and cloud based applications, service providers need to pay attention to QoS in their networks. We believe there is a need for an end-to-end approach reaching into the home as well. The Home Gateway (HG) as a key component of the home network is crucial for enabling the end-to-end solutions. UPnP-QoS has been proposed as an inhome solution for resource reservations. In this paper we assess a solution for automatic QoS reservations, on behalf of non-UPnP-QoS aware applications. Additionally we focus on an integrated end-to-end solution, combining GMPLS-based reservations in e.g., access/metro and UPnP-QoS based reservation in the home network.

QoS enabled resource allocation over an UPnP-QoS — GMPLS controlled edge

This paper focuses on the problem of coherent resource allocation within home and access networks. The interdomain QoS signaling discussed here enables the initiation of the QoS provisioning in the home and access from the end device in users home. The home network considered in this paper is UPnP-QoS enabled while the access network is GMPLS based. We propose and implement an interface between aforementioned network segments allowing for end-to-end QoS establishment. We present the QoS parameters and mechanisms in both UPnP-QoS and GMPLS and how they can be matched to create a coherent QoS architecture. Additionally we investigate the complexity of such a solution and present implementation results.

Protection switching for Carrier Ethernet multicast

This paper addresses network survivability for IPTV multicast transport in Carrier Ethernet networks. The impact of link failures is investigated and suggestions for intelligent multicast resilience schemes are proposed. In particular, functions of the multicast tree are integrated with the Carrier Ethernet transport layer, thereby optimizing the protection path with regards to delay and Quality of Experience (QoE). The proposed schemes are evaluated both through simulations and testbed experiments. Results clearly show the benefit of the integrated multicast scheme and illustrate a trade-off between recovery path length, recovery time, number of branch nodes and operational complexity. The integrated approach therefore shows significant potential to increase the QoE for IPTV users in case of network failures and recovery actions.

Integrated resource management for hybrid optical wireless (HOW) networks

Efficient utilization of available bandwidth over hybrid optical wireless networks is a critical issue, especially for multimedia applications with high data rates and stringent Quality of Service (QoS) requirements. In this paper, we propose an integrated resource management including an enhanced resource sharing scheme and an integrated admission control scheme for the hybrid optical wireless networks. It provides QoS guarantees for connections through both optical and wireless domain. Simulation results show that our proposed scheme improves QoS performances in terms of high throughput and low dropping probability.

Next Generation Network based Carrier Ethernet test bed for IPTV traffic

This paper presents a Carrier Ethernet (CE) test bed based on the Next Generation Network (NGN) framework. After the concept of CE carried out by Metro Ethernet Forum (MEF), the carrier-grade Ethernet are obtaining more and more interests and being investigated as the low cost and high performance services of transport network to carry the IPTV traffic. This test bed is approaching to support the research on providing a high performance carrier-grade Ethernet transport network for IPTV traffic.

Span Restoration in Optical Networks with Limited Wavelength Conversion

Next generation optical networks provide functionalities to dynamically provision and recover connections, while emerging technologies allow for the conversion between wavelengths. These devices are however expensive and hence it is likely that only few are deployed throughout the network. Accordingly, the unavailability of wavelength converters decreases the chance for successful connection establishment, especially in the recovery phase, where several restoration requests try to access a limited pool of resources. The recently proposed suggested vector scheme has been designed to perform converter-saving wavelength assignment in GMPLS networks. The converter saving property of the Suggested Vector is particularly desirable in span restoration, where the pre-failure path stubs have to be merged to the restoration path at the failure-adjacent nodes. In order to avoid wavelength conversion at the merging nodes, the wavelength of the connection stubs can be considered. In this study, we evaluate the recovery performance of the suggested vector scheme and a scheme exploiting standard protocol extensions only. The behavior of both schemes with a stub-aware extension for span restoration is also assessed. Our simulations show that the Suggested Vector scheme achieves a higher recovery performance than the standard scheme. Both schemes benefit from the stub-aware modification. The performance increase is especially predominant if few wavelength converters are available and at medium load ranges. Furthermore, we describe different scenarios to extend the suggested vector wavelength assignment scheme to multi-domain networks with focus on span restoration.