Juan A. Carral

Fast Path Ethernet Switching: On-demand, efficient transparent bridges for data center and campus networks

In this paper we propose Fast Path Ethernet, an evolution of the transparent bridges learning mechanisms to increase infrastructure utilization for campus and datacenter networks in a simple way. Fast Path Ethernet Switches reuse standard ARP Request and Reply packets to set up fast on-demand paths between hosts. This architecture uses the standard Ethernet frame format, so it is fully transparent to hosts and compatible with 802.1D bridging in core-island mode. A proof of concept has been implemented in Linux. Preliminary simulations in metropolitan and campus network topologies show superior performance to spanning tree and even to shortest path forwarding, at a fraction of the their complexity.

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.

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.

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.

All-Path bridging

Display Omitted Today, link-state routing protocols that compute multiple shortest paths predominate in data center and campus networks, where routing is performed either in layer three or in layer two using link-state routing protocols. But current proposals based on link-state routing do not adapt well to real time traffic variations and become very complex when attempting to balance the traffic load. We propose All-Path bridging, an evolution of the classical transparent bridging that forwards frames over shortest paths using the complete network topology, which overcomes the limitations of the spanning tree protocol. All-Path is a new frame routing paradigm based on the simultaneous exploration of all paths of the real network by a broadcast probe frame, instead of computing routes on the network graph. This paper presents All-Path switches and their differences with standard switches and describes ARP-Path protocol in detail, its path recovery mechanisms and compatibility with IEEE 802.1 standard bridges. ARP-Path is the first protocol variant of the All-Path protocol family. ARP-Path reuses the standard ARP Request and Reply packets to explore reactively the network and find the fastest path between two hosts. We compare its performance in terms of latency and load distribution with link-state shortest-path routing bridges, showing that ARP-Path distributes the load more evenly and provides lower latencies. Implementations on different platforms prove the robustness of the protocol. The conclusion is that All-Path bridging offer a simple, resilient and scalable alternative to path computation protocols.

Improving trade-offs in automated bilateral negotiations for expressive and inexpressive scenarios

In multi-issue bilateral negotiations, it is possible to make issue trade-offs to allow agents to search for win-win solutions. Different techniques may be used to perform these trade-offs. In particular, similarity criteria have been successfully used in this context. However, one drawback of similarity-based trade-offs is that this approach behaves differently depending on the knowledge each agent has about its counterpart, and depending on the order in which the different issues are considered. To address this problem, in this paper we propose three new mechanisms to improve the search for joint gains. Two of them are applicable in expressive scenarios, where agents may be willing to share preference information, while the third one is intended for inexpressive scenarios. The experimental evaluation shows how our proposals improve the efficiency and optimality of the negotiation process over previous approaches.

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.

Implementation of ARP-path low latency bridges in Linux and OpenFlow/NetFPGA

This paper describes the implementation of ARP-Path (a.k.a. FastPath) bridges, a recently proposed concept for low latency bridges, in Linux/Soekris and OpenFlow/NetFPGA platforms. These ARP-based Ethernet Switches rely on the race between the replicas of a standard ARP Request packet flooded over all links, to discover the minimum latency path to the destination host, complemented in the opposite direction by the ARP Reply packet directed to the source host. Implementations show that the protocol is loop free, 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. Implementations in Linux and OpenFlow on NetFPGA show inherent robustness and fast reconfiguration. Previous simulations showed a superior performance (throughput and delay) than the Spanning Tree Protocol and similar to shortest path routing, with lower complexity.

Evaluating native load distribution of ARP-path bridging protocol in mesh and data center

ARP-Path is a simple, low latency, shortest path bridging protocol for campus, enterprise and data center networks. We recently found that this protocol natively distributes the traffic load in networks having redundant paths of similar characteristics. The reason is that every new path between hosts is selected on-demand in a race among ARP Request packet replicas over all available paths: the first arriving replica gets its path selected on the fly. This means a continuous adaptation of new paths to variations on the load at links and bridges. To show this unique load distribution capability and path diversity property we use a number of simulations for complex scenarios, including two different simulators: one flow-based and one packet-based, and two basic topologies: data center and a regular mesh. We also verify this behavior on real hardware on a network of nine ARP-Path NetFPGA switches. The conclusion is that the ARP-Path protocol efficiently distributes traffic via alternative paths at all load levels, provided that multiple paths of similar propagation delays are available.

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.