Summary
In general, traffic is pushed through a single path despite the existence of alternative paths in networks. For example, routing solutions based on spanning tree prune the topology to prevent loops, consequently preventing also the use of alternative paths. Research on quality of service frequently advocates that the use of alternative paths is interesting for enforcing Service Level Agreements (SLAs), bypassing bottlenecks created by shortest paths. In this paper, we are interested in analyzing the support for monitoring network traffic and for provisioning of multipaths in software‐defined networking (SDN), given the strong platform it provides for experimentation of new networked solutions. Our approach firstly enriches the topology view at the control plane with data gathered through fine grain data plane monitoring. On the basis of such enriched view, our system determines the path, or multipaths, necessary to enforce the specified SLA. We propose 2 extension modules to an OpenFlow controller: SDNMon, which monitors the data plane to enrich the topology information at the control plane, and MP‐Routing, which determines a set of paths, in the absence of a single path capable of enforcing the SLA. Both modules are extensively evaluated, and the results not only demonstrate what can be achieved in terms of accuracy in SDNMon and in terms of quality of service benefits in MP‐Routing but also highlight some limitations of OpenFlow specification. On the basis of our findings, we propose a set of new counters to Per Port and Per Flow granularity levels of OpenFlow specification.
Qvalzty of servzce (QoS) is a core issue in multimedia systems. Intuitively, QoS states how good the services provided by a multimedia system are. As a rule, QoS is established through negotiation between users and service providers. The negotiation involves allocation and management of resources in order to attend a desired level of quality. Examples of such resources are peripherals, CPU , network bandwidth, data formats and synchronization levels. The process of negotiation is simple if the resources are managed by a single entit,y (eg. operating system) or by a set of entities supporting a common negotiation protocol. Unfortunately, in distributed multimedia systems the negotiation and management of resources are far from being simple tasks since resources are diversified, distributed and managed by different entities. In order to minimize such difficulties, an agent-based architecture for &OS negotiation and management is proposed in this paper. T h e architecture combines fixed and mobile agents that interact with the aim of establishing and maintaining certain level of &OS in a distributed multimedia system. This paper also describes a partial implementation of the proposed architecture using well accepted standards such as CORBA (Object Management Group's Common Object Request Bro-* affonso@dca.fee.unicamp.br t paulo@cnptia.embrapa.br tlffaina0dca.fee.unicamp.br 5 eleri@dca.
This paper presents the URBAN XOR 1 protocol, an XOR-based flat routing mechanism developed for vehicular ad hoc networks (VANETs) formed in urban scenarios. The paper firstly describes the URBAN XOR routing principle, which requires reduced knowledge about the set of nodes present in the VANET in order to provide traffic forwarding. Basically, the URBAN XOR protocol introduces the concept of local visibility, prioritizing the insertion of closer neighbors (in number of hops) in the routing tables, and simplifying the management of the frequent network mobility found in VANETs. Then, the performance of the proposed URBAN XOR protocol is compared through simulation with other topology-based and position-based protocols, characterizing its performance in terms of path availability ratio, end-to-end delay, path length and path duration. The results reveal that URBAN XOR contributes for the overall network stability, reducing the end-to-end delay due to its ability of generating shorter paths. At the same time, URBAN XOR exhibits path availability similar to other topologybased protocols, but exhibiting better path duration times.
This paper presents a proposal for shrinking the number of IPv4 FIB (Forwarding Information Base) entries required on routers. Traffic forwarding under the proposed mechanism is based on the current ASNs (Autonomous System Numbers), and can be gradually adopted by ISPs. We find that, at the cost of adding 8 bytes per packet, the proposed ASN-FWD technique is capable of providing full IPv4 traffic forwarding based on ASN information, which is correspondent to 10% of the current number of IPv4 prefixes present on FIB of routers. Among its main benefits, the proposed approach alleviates the pressure on the amount of FIB shipped on routers, and paves the way for a worldwide adoption of IPv6.
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