Evaluation of tree-based routing Ethernet

Tree-based Routing (TRE) revisits Tree-based Routing Architecture for Irregular Networks (TRAIN)—a forwarding scheme based on a spanning tree that was extended to use some shortcut links.We propose its adaptation to Ethernet, using a new type of hierarchical Ethernet addresses and a procedure to assign them to bridges. We show that compared to RSTP, TRE offers improved throughput. The impact of transient loops in TRE is lower compared to the application of the classical shortest path routing protocols to Ethernet. Finally, TRE is self-configuring and its forwarding process is simpler and more efficient than in standard Ethernet and shortest path routing proposals.Publicad

Flow-Path: An AllPath flow-based protocol

The work at: The 37th IEEE Conference on Local Computer Networks (LCN). Clearwater, Florida, USA. Date: 22-25 October 2012This paper describes Flow-Path, an AllPath flowbased switching protocol that features improved load adaptive properties. Upon arrival of a new flow to the network, it explores every possible path reaching from source to destination host and selects the lowest latency path at the moment. It is based on the same basic principle than ARPPath, that is, snooping the ARP protocol dialog (request and reply messages) to explore all available paths at the same time that address resolution takes place, but it is flow-based instead of source address-based. While preserving the main advantages of ARP-Path: shortest path bridging exploiting the full network topology, Flow-Path has the advantages of full independence of flows at the time of path creation and guarantees path symmetry (congruency) and increased path diversity. Flow-Path thus improves load distribution, at the expense of increased address table size in each bridge.This work was supported in part by grants from Comunidad de Madrid and Comunidad de Castilla-La Mancha through Projects MEDIANET-CM (S-2009/TIC- 1468) and EMARECE (PII1I09-0204-4319).Publicad

Hierarchical Up/Down Routing Architecture for Ethernet backbones and campus networks

We describe a new layer two distributed and scalable routing architecture. It uses an automatic hierarchical node identifier assignment mechanism associated to the rapid spanning tree protocol. Enhanced up/down mechanisms are used to prohibit some turns at nodes to break cycles, instead of blocking links like the spannning tree protocol does. The protocol performance is similar or better than other turn prohibition algorithms recently proposed with lower complexity O(Nd) and better scalability. Simulations show that the fraction of prohibited turns over random networks is less than 0.2. The effect of root bridge election on the performance of the protocol is limited both in the random and regular networks studied. The use of hierarchical, tree-descriptive addresses simplifies the routing, and avoids the need of all nodes having a global knowleddge of the network topology. Routing frames through the hierarchical tree at very high speed is possible by progressive decoding of frame destination address, without routing tables or port address learning. Coexistence with standard bridges is achieved using combined devices: bridges that forward the frames having global destination MAC addresses as standard bridges and frames with local MAC frames with the proposed protocol.Publicad

ARP-Path: ARP-based Shortest Path Bridges

This letter is a summary proposal for an evolution of the Ethernet transparent bridge paradigm that provides simple, shortest path bridging in campus networks. ARP-Path Ethernet Switches set up an on-demand path between two hosts just reusing and flooding the standard ARP request frame through all links and confirming the path reaching to the destination host with the ARP reply frame. ARP-Path uses the standard Ethernet frame format, is fully transparent to hosts and does not require spanning tree or link state protocol. Simulation results show superior performance to spanning tree and similar to shortest path routing, with lower complexity. Our implementations confirm backward compatibility, robustness and performance.This work was supported in part by grants from Comunidad de Madrid and Comunidad de Castilla la Mancha through Projects MEDIANET-CM (S- 2009/TIC-1468) and EMARECE (PII1I09-0204-4319).Publicad

Evolución conceptual de los protocolos de puentes transparentes

Los puentes Ethernet transparentes son un elemento cada vez más importante en las redes\ud de telecomunicaciones. Este artículo ofrece una visión panorámica de la evolución conceptual de los\ud paradigmas de puentes durante las últimas décadas, desde los puentes transparentes con árbol de\ud expansión hasta las propuestas actualmente en estandarización: por una parte Shortest Path Bridges,\ud Provider Bridges y Provider Backbone Bridges en el IEEE 802.1; por otra parte Routing Bridges en el\ud IETF. Estas propuestas buscan aumentar la escalabilidad y obtener una alta utilización de la infraestructura\ud de red, así como la provisión de servicios basados en Ethernet a gran número de usuarios. Mediante\ud un mapa genealógico y una tabla se resumen e ilustran los aspectos funcionales, la evolución de los\ud puentes propuestos en cuanto a los mecanismos básicos empleados para el encaminamiento, reenvío\ud y la prevención de bucles tales como protocolos de vector distancia y de estado de enlaces, árboles\ud múltiples de expansión, jerarquización mediante encapsulado de tramas y prohibición de algunos giros\ud en los nodos. La evolución reciente de las propuestas muestra claramente varias tendencias: el predominio\ud de los protocolos de estado de enlaces como IS-IS para el encaminamiento y/o construcción de\ud árboles múltiples, de los mecanismos de encapsulado, y la multiplicación de tipos de identificadores\ud para etiquetar y procesar separada y homogéneamente miles de servicios y clientes

Implementing ARP-Path Low Latency Bridges in NetFPGA

The demo is focused on the implementation of ARP-Path (a.k.a. FastPath) bridges, a recently proposed concept for low latency bridges. ARP-Path Bridges rely on the race between broadcast ARP Request packets, to discover the minimum latency path to the destination host. Several implementations (in Omnet++, Linux, OpenFlow, NetFPGA) have shown that ARP-Path exhibits loop-freedom, does not block links, is fully transparent to hosts and neither needs a spanning tree protocol to prevent loops nor a link state protocol to obtain low latency paths. This demo compares our hardware implementation on NetFPGA to bridges running STP, showing that ARP-Path finds lower latency paths than STP.Comunidad de MadridJunta de Comunidades de Castilla-La Manch

HURP/HURBA: Zero-configuration hierarchical Up/Down routing and bridging architecture for Ethernet backbones and campus networks

Ethernet switched networks do not scale appropriately due to limitations inherent to the spanning tree protocol. Ethernet architectures based on routing over a virtual topology in which turns are prohibited offer improved performance over spanning tree, although in some cases suffer from excessive computational complexity. Up/Down routing is a turn prohibition algorithm with low computational complexity. In this paper we propose HURBA, a new layer-two architecture that improves Up/Down routing performance due to an optimization based on the use of hierarchical addressing, while preserving the computational complexity of Up/Down. The resulting architecture requires zero-configuration, uses the same frame format as Ethernet, allows upgrades by software update, and is compatible with 802.1D bridges by means of encapsulation. HURP protocol builds automatically a core with the interconnected HURP routing bridges and the standard bridges get connected to the edges in standard spanning trees. Simulations show that the performance of HURP, evaluated over various combinations of network topology and size, is close to the one of shortest path, is consistently better than that of Up/Down, and is equal or better than Turn Prohibition, with the advantage of having a lower complexity.En prens

The challenge of sustainability: Long-term results from the Fifty-Fifty peer group-based intervention in cardiovascular risk factors.

The Fifty-Fifty trial demonstrated that a peer-group-based intervention was able to improve healthy behaviors in individuals with cardiovascular (CV) risk factors immediately post-intervention. To determine the long-term sustainability of a one-year peer-group-based intervention focused on CV health and behavior. A total of 543 adults aged 25 to 50 years with at least 1 CV risk factor were screened and recruited, received initial training through workshops, and were then randomized 1:1 to a peer-group-based intervention group (IG) or a self-management control group (CG) for 12 months. At a median of 52 months from baseline, 321 participants were re-assessed (~60% retention). The primary outcome was the mean change in a composite health score related to blood pressure, exercise, weight, alimentation, and tobacco use (Fuster-BEWAT score [FBS], range 0-15). Intervention effects were assessed using linear-mixed effects models. The mean age of retained participants was 48.0 years (SD: 5.4), and 73% were female. Consistent with previous results, the change of overall FBS was significantly greater in the IG than in the CG at 12-month follow-up (between-group difference, 0.60 points; 95% CI, 0.08-1.12; P = .025). Assessment of long-term sustainability (52-month follow-up) showed that there were no between-group differences in the mean overall FBS (IG mean score, 8.52; 95% CI, 7.97-9.07 vs CG mean score, 8.51; 95% CI, 7.93-9.10; P = .972) or in the change of overall FBS from screening (IG mean change, 0.64; 95% CI, 0.00-1.28; CG mean change, 0.46; 95% CI, -0.20-1.12; P = .497). A one-year peer-group-based intervention showed favorable results at immediate post-intervention but did not demonstrate significant differences between the IG and CG at 52 months. Combination of an initial training period (workshops) with the maintenance of peer-support groups or other re-intervention strategies may be required to achieve sustained effects on healthy behaviors. ClinicalTrials.gov identifier NCT02367963. Registered (https://clinicaltrials.gov/show/NCT02367963).This study was co-funded by the SHE Foundation -“la Caixa” Foundation (LCF/PR/CE16/10700001 and LCF/PR/MS19/12220001) and the Ministry of Health, Social Services and Equality. R.F-J is recipient of funding from the Instituto de Salud Carlos III-Fondo de Investigacion Sanitaria (PI19/01704) co-funded by the European Regional Development Fund/European Social Fund (“A way to make Europe”/“Investing in your future”). The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministry of Science and Innovation, and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505).S