Department of Computer Science and Information Systems
Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1928
Browse
7 results
Search Results
Item Real-time monitoring of network latency in Software Defined Networks(IEEE, 2015) Haribabu, KLatency in a network is an important parameter that can be utilized by Service providers and end users alike. Delay on a network path is often measured using end-to-end probing packets. When multiple end systems measure end-to-end latency, there are overlaps in their paths. Since end systems do not have this knowledge, it results in redundant work and network overhead. In this paper, we propose a method to measure end-to-end path latency in Software Defined Networks (SDN). This method avoids redundant work and measures latency in real-time. Our proposal is an improvement over the looping technique. We simplified the looping technique by using IP TTL as a counter. In order to avoid duplicate work, latency is measured per link and stored in the controller. End systems may register their flow labels with the SDN controller to receive latency information. For each registered flow, controller composes individual link latencies on that path to compute end-to-end latency. We also propose another approach to measure latency using queue lengths at network switches. This technique removes network overhead. In our simulations, improved looping technique is found to be giving better results with reduced computational and network overhead, while the proposed queue length technique shows comparable results.Item Real Time Monitoring of Packet Loss in Software Defined Networks(Springer, 2017-12) Haribabu, K; Sinha, YashIn order to meet QoS demands from customers, currently, ISPs over-provision capacity. Networks need to continuously monitor performance metrics, such as bandwidth, packet loss etc., in order to quickly adapt forwarding rules in response to changes in the workload. The packet loss metric is also required by network administrators and ISPs to identify clusters in network that are vulnerable to congestion. However, the existing solutions either require special instrumentation of the network or impose significant measurement overhead. Software-Defined Networking (SDN), an emerging paradigm in networking advocates separation of the data plane and the control plane, separating the network’s control logic from the underlying routers and switches, leaving a logically centralized software program to control the behavior of the entire network, and introducing network programmability. Further, OpenFlow allows to implement fine-grained Traffic Engineering (TE) and provides flexibility to determine and enforce end-to-end QoS parameters.Item Estimation of Raw Packets in SDN(Springer, 2017-12) Haribabu, K; Sinha, YashIn SDN based networks, for network management such as monitoring, performance tuning, enforcing security, configurations, calculating QoS metrics etc. a certain fraction of traffic is responsible. It consists of packets for many network protocols such as DHCP, MLD, MDNS, NDP etc. Most of the time these packets are created and absorbed at midway switches. We refer to these as raw packets. Cumulative statistics of sent and received traffic is sent to the controller by OpenFlow compliant switches that includes these raw packets. Although, not part of the data traffic these packets get counted and leads to noise in the measured statistics and thus, hamper the accuracy of methods that depend on these statistics such as calculation of QoS metrics. In this paper, we propose a method to estimate the fraction of the network traffic that consists of raw packets in Software Defined Networks. The number of raw packets transferred depends on the number of switches and hosts in the network and it is a periodic function of time. Through experiments on several network topologies, we have estimated a way to find a cap on the generated raw packets in the network, using spanning tree information about the topology.Item OpenSnap: Collection of Globally Consistent Statistics in Software Defined Network(IEEE, 2019) Haribabu, K; Bhatia, AshutoshCapturing and monitoring the global state of the network in a software defined network (SDN) is crucial for efficient routing, performance monitoring, Quality of Service (QoS) assurance, etc. The two major existing approaches for statistics collection in SDN are polling-based and event-based. Due to the asynchronous nature of the network, statistics collected through polling have inconsistencies and are not suitable for capturing the consistent global state of the network. On the other hand, event-based monitoring schemes may give sparse information about the network. Globally consistent state detection is well studied for asynchronous systems. However, current SDN standards such as OpenFlow do not support any functionality to collect globally consistent statistics. In this paper, we propose “OpenSnap”, an algorithm to determine the globally consistent state of the system. To support OpenSnap, we extend the OpenFlow protocol by adding a new action. The experimental results show that the statistics collected at the SDN controller using the proposed OpenSnap algorithm are always consistent.Item A survey: Hybrid SDN(Elsevier, 2017-12) Haribabu, K; Sinha, YashA full deployment of Software Defined Networking (SDN) paradigm poses multi-dimensional challenges viz., technical, financial and business challenges. Technical challenges of scalability, fault tolerance, centralization guarantees exist. Financial challenges of budget constraints, non-availability of phased transition model exist. Business challenges like acceptability, building confidence among network operators etc. exist. Therefore, a direct and sudden transition from legacy networks to pure SDN seems unlikely. A hybrid deployment of SDN can be one of the plausible intermediate paths, primarily because it provides an environment where both legacy and SDN nodes can work together. Thus, an incremental deployment strategy can be developed. Further, hybrid SDN can enforce the benefits of both the traditional networks and SDN paradigm. Hybrid SDN deployment has many advantages including adaptability to budget constraints, central programmability of the network, fallback to time-tested legacy mechanisms and so on. But there are challenges specific to hybrid models, like added complexity of running multiple paradigms together, realizing cooperation between control planes, etc. We envision that more research work is needed to maximize the benefits and limit the drawbacks.Item GlobeSnap: An Efficient Globally Consistent Statistics Collection for Software-Defined Networks(Springer, 2021-05) Haribabu, K; Bhatia, AshutoshSoftware defined networking (SDN) controller requires crucial statistics like flow-wise statistics from the switches to make decisions related to routing, load balancing, and QoS provisioning. These statistics, when viewed across the switches are likely to be inconsistent if a specific order is not enforced while collecting statistics. Collecting consistent statistics requires coordination among all the participating switches. A few approaches in the literature collect globally consistent statistics of a network in the SDN domain. However, these approaches are not time-efficient, robust, and synchronous for OpenFlow based networks. We propose, GlobeSnap, a time-efficient, robust, and synchronous method to collect globally consistent statistics for OpenFlow networks. GlobeSnap collects consistent statistics for all flows in a single round and is therefore, time-efficient. Moreover, GlobeSnap is robust since it resumes the statistics collection process from where it left in case of interruption. GlobeSnap also provides a near-synchronous snapshot of statistics of the switches traversed by a given flow. We also propose a mechanism to persistently store states in OpenFlow based networks using registers, multiple flow tables, and multiple pipelines. We find that GlobeSnap outperforms the state-of-the-art approaches in consistency evaluation. Further we present two use-cases which are sensitive to inconsistent flow statistics, that is, computing packet loss and identifying bottleneck links, to show the time-efficiency, robustness, and synchronicity of GlobeSnap. GlobeSnap provides 100% consistency in OpenFlow based SDN networks. Whereas the existing methods achieve a maximum of 59.89% consistency.Item qMon: A method to monitor queueing delay in OpenFlow networks(IEEE, 2022-08) Haribabu, K; Bhatia, AshutoshIn software-defined networking (SDN), the decoupled architecture provides opportunities for efficiently measuring critical quality of service (QoS) parameters, such as delay. Existing approaches, to dynamically obtain delay, are based around calculating the transit time of a probe packet that travels through the data links. These approaches are not efficient as the probe packet injected into the data plane incurs considerable overhead. Additionally, a separate probe packet is required to measure the delay of each queue if more than one queue is present on the egress port of a switch. Thus, these approaches are not scalable. In this paper, we propose an efficient passive delay estimation method, queueing delay monitoring (qMon), to monitor queueing delay in SDN networks. qMon leverages the OpenFlow protocol to obtain queue statistics from switches at regular intervals, which are further employed to estimate the mean queueing delay for each interval. Thus, the proposed approach differs from the existing approaches as no packet is injected into the data plane to measure delay. The results show that for Poisson traffic and for bursty traffic with large ON intervals, round trip time (RTT) values estimated using qMon and ping utility demonstrate high correlation when the measured RTT value is considered as time-series data.