Browsing by Author "Tahiliani, M.P."

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A principled look at the utility of feedback in congestion control
(Association for Computing Machinery, 2019) Tahiliani, M.P.; Misra, V.; Ramakrishnan, K.K.
Networked applications are ubiquitous and their performance requirements are becoming increasingly stringent. Network congestion can seriously impact performance contributing to increased latency, packet loss and poor throughput. To address these problems, the networking community has come up with a large number of congestion control algorithms. Congestion control schemes developed over the past few decades can be classified into two broad classes: one based on an end-system's perception of network congestion and the other based on the network providing feedback to flows that pass through it. In this paper, we make the observation that the pure end-system based congestion control schemes are faced with the significant challenge of receiving ambiguous signals that make it difficult to infer where the congestion is occurring and if this flow is even the cause of that congestion. This ambiguity makes it difficult for pure end-system based control schemes to achieve fairness across different flows. Modern routers and switches in the meantime, have grown in computing capability and can generate fine grained feedback at line speeds for flows traversing them. We show that even relatively simple feedback generated in-network at the point of congestion eliminates the ambiguities faced by pure end-system based congestion control mechanisms, thus ensuring the network functions at the right fair and efficient operating point. We provide the theoretical underpinnings establishing the need for in-network feedback to enable the network to operate at a unique fixed point at the intersection of the desired fair and efficient operation regimes, and demonstrate through emulation experiments that our use of the well-established and studied PI-control for Active Queue Management and Explicit Congestion Notification meets the goals of low latency, high throughput and fine granularity control of the queue while achieving fairness. Â© 2019 Copyright held by the owner/author(s). Publication rights licensed to ACM.
Achieving Guaranteed Performance for Protection Traffic in Smart Grid Wide-Area Networks
(2019) Adrah, C.M.; Kamath, A.K.; Bjornstad, S.; Tahiliani, M.P.
Recent years, tele-protection applications in utility grids have been deployed using Ethernet. However, Ethernet without Time Sensitive Network (TSN) mechanisms is nondeterministic. Hence, challenges of the queuing delays occurring on multi-hop paths result in Packet Delay Variations (PDV) and may even result in packet losses due to buffer overflows. There have been recommendations to use Priority Scheduling (PS) to lower the latency of tele-protection messages. However, for PS, maximum PDV occurs on higher priority packets when contending with lower priority packets, needing to wait until a lower priority packet with maximum length have exited a switch. In this paper, we explore through a performance simulation study the suitability of applying FUSION in smart grid tele-protection applications. FUSION is a packet switched principle applying Ethernet, offering circuit-switched quality of service with deterministic latency, zero packet loss and ultra-low PDV for high priority packets. We demonstrate FUSION performance in tele-protection for power system networks, and compare it with Strict Priority Queuing (SPQ), which is recommended for realtime industrial applications. Our results show that by applying FUSION, we are able to guarantee a fixed delay, zero PDV and packet loss through the network. Furthermore, we show that through proper network dimensioning, lower priority traffic can additionally be added with delays within acceptable limits. � 2019 IEEE.
Achieving Guaranteed Performance for Protection Traffic in Smart Grid Wide-Area Networks
(Institute of Electrical and Electronics Engineers Inc., 2019) Adrah, C.M.; Kamath, A.K.; BjoÌŠrnstad, S.; Tahiliani, M.P.
Recent years, tele-protection applications in utility grids have been deployed using Ethernet. However, Ethernet without Time Sensitive Network (TSN) mechanisms is nondeterministic. Hence, challenges of the queuing delays occurring on multi-hop paths result in Packet Delay Variations (PDV) and may even result in packet losses due to buffer overflows. There have been recommendations to use Priority Scheduling (PS) to lower the latency of tele-protection messages. However, for PS, maximum PDV occurs on higher priority packets when contending with lower priority packets, needing to wait until a lower priority packet with maximum length have exited a switch. In this paper, we explore through a performance simulation study the suitability of applying FUSION in smart grid tele-protection applications. FUSION is a packet switched principle applying Ethernet, offering circuit-switched quality of service with deterministic latency, zero packet loss and ultra-low PDV for high priority packets. We demonstrate FUSION performance in tele-protection for power system networks, and compare it with Strict Priority Queuing (SPQ), which is recommended for realtime industrial applications. Our results show that by applying FUSION, we are able to guarantee a fixed delay, zero PDV and packet loss through the network. Furthermore, we show that through proper network dimensioning, lower priority traffic can additionally be added with delays within acceptable limits. Â© 2019 IEEE.
Adaptive RED for FreeBSD: Design, Implementation and Challenges
(2019) Pandey, A.; Anand, T.; Shah, M.; Tahiliani, M.P.
Bufferbloat problem arises due to buffering of large amounts of data in queues, owing to the large size of these queues. Bufferbloat being a relatively new phenomenon meant that earlier queue management algorithms did not specifically address this problem. Despite this issue, there is merit in analysing and evaluating old queue management algorithms which have helped alleviate the undesirable performance issues that arose due to persistently full buffers. One of the earliest and most significantly studied Active Queue Management (AQM) algorithms is Random Early Drop (RED). RED helps to keep the average size of the queues low and allow occasional bursts of packets through the queue. Once the number of packets queued crosses a minimum threshold, incoming packets are dropped with a random probability. However, the resulting average queue length is quite sensitive to the level of congestion and the RED parameter settings. Adaptive RED (ARED) solves most of the issues faced by RED with minimal changes and leaves its basic idea intact. The ARED algorithm regularly adapts the value of the maximum dropping probability and ensures that the queue length stays within the targeted range. Despite its ability to resolve the inherent problems in RED, ARED went largely unnoticed for several years, until the issue of Bufferbloat arose. Although ARED predates Bufferbloat, its fundamental design makes it an effective solution to handle Bufferbloat. This discovery led to the implementation of ARED in Linux and in network simulators like ns-3. Besides Linux, FreeBSD is one of the most popular open source operating systems. Although RED is supported in FreeBSD, ARED is not. Since ARED is one of the viable solutions to tackle Bufferbloat, this paper discusses the design and implementation of ARED in FreeBSD. We also detail the challenges faced during the implementation, and validate through real testbed experiments that our implementation in FreeBSD exhibits ARED's key characteristics. � 2019 IEEE.
Adaptive RED for FreeBSD: Design, Implementation and Challenges
(Institute of Electrical and Electronics Engineers Inc., 2019) Pandey, A.; Anand, T.; Shah, M.; Tahiliani, M.P.
Bufferbloat problem arises due to buffering of large amounts of data in queues, owing to the large size of these queues. Bufferbloat being a relatively new phenomenon meant that earlier queue management algorithms did not specifically address this problem. Despite this issue, there is merit in analysing and evaluating old queue management algorithms which have helped alleviate the undesirable performance issues that arose due to persistently full buffers. One of the earliest and most significantly studied Active Queue Management (AQM) algorithms is Random Early Drop (RED). RED helps to keep the average size of the queues low and allow occasional bursts of packets through the queue. Once the number of packets queued crosses a minimum threshold, incoming packets are dropped with a random probability. However, the resulting average queue length is quite sensitive to the level of congestion and the RED parameter settings. Adaptive RED (ARED) solves most of the issues faced by RED with minimal changes and leaves its basic idea intact. The ARED algorithm regularly adapts the value of the maximum dropping probability and ensures that the queue length stays within the targeted range. Despite its ability to resolve the inherent problems in RED, ARED went largely unnoticed for several years, until the issue of Bufferbloat arose. Although ARED predates Bufferbloat, its fundamental design makes it an effective solution to handle Bufferbloat. This discovery led to the implementation of ARED in Linux and in network simulators like ns-3. Besides Linux, FreeBSD is one of the most popular open source operating systems. Although RED is supported in FreeBSD, ARED is not. Since ARED is one of the viable solutions to tackle Bufferbloat, this paper discusses the design and implementation of ARED in FreeBSD. We also detail the challenges faced during the implementation, and validate through real testbed experiments that our implementation in FreeBSD exhibits ARED's key characteristics. Â© 2019 IEEE.
AMul: Adaptive multicast routing protocol for multi-hop wireless networks
(2011) Panwala, V.; Hegde, S.; Tahiliani, M.P.
Wireless Networks have evolved as promising technology for numerous applications to provide Internet access to fixed and mobile wireless devices. Multicasting plays a crucial role in many applications of Wireless Networks. Several routing protocols have been proposed for multicast communication in mobile wireless networks. In this paper we propose a reactive and receiver initiated multicast routing protocol called Adaptive Multicast (AMul) to provide better Quality of Service (QoS) in Wireless Networks. Using simulations, we compare AMul with Protocol for Unified Multicasting through Announcements (PUMA) which is also a reactive and receiver initiated multicast routing protocol for Multi- Hop Wireless Networks. Based on the simulation results, we observe that AMul reduces the overall end to end delay while inducing negligible control overhead in the network. � Springer-Verlag 2011.
AMul: Adaptive multicast routing protocol for multi-hop wireless networks
(2011) Panwala, V.; Hegde, S.; Tahiliani, M.P.
Wireless Networks have evolved as promising technology for numerous applications to provide Internet access to fixed and mobile wireless devices. Multicasting plays a crucial role in many applications of Wireless Networks. Several routing protocols have been proposed for multicast communication in mobile wireless networks. In this paper we propose a reactive and receiver initiated multicast routing protocol called Adaptive Multicast (AMul) to provide better Quality of Service (QoS) in Wireless Networks. Using simulations, we compare AMul with Protocol for Unified Multicasting through Announcements (PUMA) which is also a reactive and receiver initiated multicast routing protocol for Multi- Hop Wireless Networks. Based on the simulation results, we observe that AMul reduces the overall end to end delay while inducing negligible control overhead in the network. Â© Springer-Verlag 2011.
Analysis of cautious adaptive RED (CARED)
(2013) Tahiliani, M.P.; Shet, K.C.
Internet in the present scenario has become a gigantic source of information. There has been a tremendous rise in the variety of Internet applications with each application demanding a specific performance criteria to be satisfied. Routers presently use Passive Queue Management (PQM) mechanisms and hence, merely have any control over the queue occupancy. Therefore, there has been an increased interest in exploring Active Queue Management (AQM) in Internet routers so as to reduce the queue latency and meet the demands of time sensitive applications. In this paper, we mainly focus on analyzing the AQM mechanism which we proposed recently, named Cautious Adaptive Random Early Detection (CARED). We study the effectiveness of CARED by carrying out simulations in ns-2 and comparing its performance with Adaptive RED (ARED) and Refined Adaptive RED (Re-ARED) in a wide variety of Internet scenarios. Based on the simulation results obtained, we highlight the advantages of CARED in terms of throughput, packet drop rate and the stability of the average queue size. � 2013 IEEE.
Analysis of cautious adaptive RED (CARED)
(2013) Tahiliani, M.P.; Shet, K.C.
Internet in the present scenario has become a gigantic source of information. There has been a tremendous rise in the variety of Internet applications with each application demanding a specific performance criteria to be satisfied. Routers presently use Passive Queue Management (PQM) mechanisms and hence, merely have any control over the queue occupancy. Therefore, there has been an increased interest in exploring Active Queue Management (AQM) in Internet routers so as to reduce the queue latency and meet the demands of time sensitive applications. In this paper, we mainly focus on analyzing the AQM mechanism which we proposed recently, named Cautious Adaptive Random Early Detection (CARED). We study the effectiveness of CARED by carrying out simulations in ns-2 and comparing its performance with Adaptive RED (ARED) and Refined Adaptive RED (Re-ARED) in a wide variety of Internet scenarios. Based on the simulation results obtained, we highlight the advantages of CARED in terms of throughput, packet drop rate and the stability of the average queue size. Â© 2013 IEEE.
Analysis of sfqCoDel for Active Queue Management
(2014) Rao, V.P.; Tahiliani, M.P.; Shenoy, U.K.K.
The availability of cheaper and high capacity Random Access Memory (RAM) has resulted in the growth of buffer size in all the computing devices. This aberrant increase of buffer capacity in network devices has resulted into high latency, leading to reduced throughput; thus decreasing the tendency of absorbing spontaneous burst of traffic. The requirement for Active Queue Management (AQM) has been evident for decades. These solutions require various parameter configuration and are dependent on a particular network condition to work efficiently. Hence an algorithm which is simple, efficient, does not require setting of parameters and works seamlessly irrespective of the network condition is required. Even though Controlled Delay (CoDel) is parameterless and adapts to dynamically changing link rates with no negative impact on utilization, it deviates from its primary purpose of reducing congestion when there is an increase in RTT and when congestion level varies abruptly. As a consequence, a variant of CoDel called Stochastic Fair Queue CoDel (sfqCoDel) is simulated and compared. The Stochastic Fair Queue CoDel proactively drops packets which occupy reasonably larger bandwidth as compared to CoDel, which proactively drops packet irrespective of the bandwidth consumption by packets. This paper aims to perform a comprehensive analysis of Stochastic Fair Queue CoDel for Active Queue Management. A comparison is also carried out between sfqCoDel with CoDel. The sfqCoDel appears to be much better than CoDel in certain areas where CoDel fails to perform well. � 2014 IEEE.
Analysis of sfqCoDel for Active Queue Management
(IEEE Computer Society help@computer.org, 2014) Rao, V.P.; Tahiliani, M.P.; Shenoy, U.K.K.
The availability of cheaper and high capacity Random Access Memory (RAM) has resulted in the growth of buffer size in all the computing devices. This aberrant increase of buffer capacity in network devices has resulted into high latency, leading to reduced throughput; thus decreasing the tendency of absorbing spontaneous burst of traffic. The requirement for Active Queue Management (AQM) has been evident for decades. These solutions require various parameter configuration and are dependent on a particular network condition to work efficiently. Hence an algorithm which is simple, efficient, does not require setting of parameters and works seamlessly irrespective of the network condition is required. Even though Controlled Delay (CoDel) is parameterless and adapts to dynamically changing link rates with no negative impact on utilization, it deviates from its primary purpose of reducing congestion when there is an increase in RTT and when congestion level varies abruptly. As a consequence, a variant of CoDel called Stochastic Fair Queue CoDel (sfqCoDel) is simulated and compared. The Stochastic Fair Queue CoDel proactively drops packets which occupy reasonably larger bandwidth as compared to CoDel, which proactively drops packet irrespective of the bandwidth consumption by packets. This paper aims to perform a comprehensive analysis of Stochastic Fair Queue CoDel for Active Queue Management. A comparison is also carried out between sfqCoDel with CoDel. The sfqCoDel appears to be much better than CoDel in certain areas where CoDel fails to perform well. Â© 2014 IEEE.
Anomalous event detection methodologies for surveillance application: An insight
(2017) Rao T.J.N.; Tahiliani, M.P.; Girish G.N.; Rajan J.
Automatic visual surveillance systems serve as in-place threat detection devices being able to detect and recognize anomalous activities which otherwise would lead to potentially harmful situations, and alert the concerned authorities to take appropriate counter actions. However, development of an efficient visual surveillance system is quite challenging. Designing an unusual activity detection mechanism which is accurate and real-time is the primary challenge. Review of literature carried out led to the inference that there are some attributes which are essential for a successful unusual event detection mechanism for surveillance application. The desired approach must detect genuine anomalies in real-world scenarios with acceptable accuracy, should adapt to changing environments and, should require less computational time and memory. In this chapter, an attempt has been made to provide an insight into some of the prominent approaches employed by researchers to solve these issues with a hope that it will benefit researchers towards developing a better surveillance system. © 2018 IGI Global. All rights reserved.
Anomalous event detection methodologies for surveillance application: An insight
(2018) Rao T.J.N.; Girish G.N.; Tahiliani, M.P.; Rajan J.
Automatic visual surveillance systems serve as in-place threat detection devices being able to detect and recognize anomalous activities which otherwise would lead to potentially harmful situations, and alert the concerned authorities to take appropriate counter actions. However, development of an efficient visual surveillance system is quite challenging. Designing an unusual activity detection mechanism which is accurate and real-time is the primary challenge. Review of literature carried out led to the inference that there are some attributes which are essential for a successful unusual event detection mechanism for surveillance application. The desired approach must detect genuine anomalies in real-world scenarios with acceptable accuracy, should adapt to changing environments and, should require less computational time and memory. In this chapter, an attempt has been made to provide an insight into some of the prominent approaches employed by researchers to solve these issues with a hope that it will benefit researchers towards developing a better surveillance system. © 2019 by IGI Global.
Anomalous event detection methodologies for surveillance application: An insight
(IGI Global, 2018) Rao, T.J.N.; Girish, G.N.; Tahiliani, M.P.; Rajan, J.
Automatic visual surveillance systems serve as in-place threat detection devices being able to detect and recognize anomalous activities which otherwise would lead to potentially harmful situations, and alert the concerned authorities to take appropriate counter actions. However, development of an efficient visual surveillance system is quite challenging. Designing an unusual activity detection mechanism which is accurate and real-time is the primary challenge. Review of literature carried out led to the inference that there are some attributes which are essential for a successful unusual event detection mechanism for surveillance application. The desired approach must detect genuine anomalies in real-world scenarios with acceptable accuracy, should adapt to changing environments and, should require less computational time and memory. In this chapter, an attempt has been made to provide an insight into some of the prominent approaches employed by researchers to solve these issues with a hope that it will benefit researchers towards developing a better surveillance system. © 2019 by IGI Global.
Anomalous event detection methodologies for surveillance application: An insight
(IGI Global, 2017) Rao, T.J.N.; Tahiliani, M.P.; Girish, G.N.; Rajan, J.
Automatic visual surveillance systems serve as in-place threat detection devices being able to detect and recognize anomalous activities which otherwise would lead to potentially harmful situations, and alert the concerned authorities to take appropriate counter actions. However, development of an efficient visual surveillance system is quite challenging. Designing an unusual activity detection mechanism which is accurate and real-time is the primary challenge. Review of literature carried out led to the inference that there are some attributes which are essential for a successful unusual event detection mechanism for surveillance application. The desired approach must detect genuine anomalies in real-world scenarios with acceptable accuracy, should adapt to changing environments and, should require less computational time and memory. In this chapter, an attempt has been made to provide an insight into some of the prominent approaches employed by researchers to solve these issues with a hope that it will benefit researchers towards developing a better surveillance system. © 2018 IGI Global. All rights reserved.
Ant-CAMP: Ant based congestion adaptive multi-path routing protocol for wireless networks
(2011) Raval, C.; Hegde, S.; Tahiliani, M.P.
The advent of mobile computing devices and wide deployment of wireless networks have led to an exponential increase in the internet traffic. Long congestion epochs and frequent link failures in wireless network lead to more number of packets being dropped and incur high end-to-end delay, thereby degrading the overall performance of the network. Congestion control, though mainly incorporated at the transport layer, if coupled with the routing protocols, can significantly improve overall performance of the network. In this paper we propose Ant based Congestion Adaptive Multipath (Ant-CAMP) routing protocol that aims to avoid congestion by proactively sending congestion notification to the sender. The proposed Ant-CAMP routing protocol is implemented in Network Simulator-2 (NS-2) and its performance is compared with Ad-hoc On Demand Multi-Path Distance Vector (AOMDV) in terms of Packet Drops due to Congestion, Packet Delivery Fraction and Average End-to-End Delay. � Springer-Verlag 2011.
Ant-CAMP: Ant based congestion adaptive multi-path routing protocol for wireless networks
(2011) Raval, C.; Hegde, S.; Tahiliani, M.P.
The advent of mobile computing devices and wide deployment of wireless networks have led to an exponential increase in the internet traffic. Long congestion epochs and frequent link failures in wireless network lead to more number of packets being dropped and incur high end-to-end delay, thereby degrading the overall performance of the network. Congestion control, though mainly incorporated at the transport layer, if coupled with the routing protocols, can significantly improve overall performance of the network. In this paper we propose Ant based Congestion Adaptive Multipath (Ant-CAMP) routing protocol that aims to avoid congestion by proactively sending congestion notification to the sender. The proposed Ant-CAMP routing protocol is implemented in Network Simulator-2 (NS-2) and its performance is compared with Ad-hoc On Demand Multi-Path Distance Vector (AOMDV) in terms of Packet Drops due to Congestion, Packet Delivery Fraction and Average End-to-End Delay. Â© Springer-Verlag 2011.
Automated rice mapping using multitemporal Sentinel-1 SAR imagery using dynamic threshold and slope-based index methods
(Elsevier B.V., 2025) Aishwarya Hegde, A.H.; Umesh, P.; Tahiliani, M.P.
Rice cultivation plays a crucial role in food security and economic development, particularly in regions like India, due to its vast population and position as the top rice producer globally. This work introduces a novel framework, the Rice Mapping Method (RMM), which leverages Multitemporal Sentinel-1 Synthetic Aperture Radar (SAR) imagery for automated rice mapping. Contrary to the traditional approaches, RMM combines the Dynamic Threshold Method (DTM) for robust rice field identification and a slope-based index for classifying single and double cropping practices. By analyzing VH backscatter patterns and employing specific thresholds, DTM separates rice pixels from the other background pixels. The DTM, which relies on VH backscatter values during the growing season, has been tested across various rice cultivation landscapes, demonstrating high accuracy up to 0.95. DTM is also tested on different rice-growing areas such as the hilly Kodagu district, with an F1 Score of 0.96, and in the flooded delta region of Kuttanad, achieving an F1 Score of 0.93. The Slope-based Index I(r,c) is introduced to differentiate the single and double cropping pixels by calculating the index for the second season of cropping and gives F1 Score of 0.81. The DTM's effectiveness in rice field identification is evaluated by comparing it to the classification of the Bi-directional Gated Recurrent Unit (Bi-GRU) network. Similarly, the Slope-based Index is compared with other established automated rice mapping methods to assess its accuracy in distinguishing cropping patterns. RMM was successfully applied in mapping rice-growing areas in the Udupi district for 2021, estimating Kharif and Rabi season areas, the estimated rice area is compared to official statistics by the Directorate of Economics and Statistics, Karnataka State. The proposed RMM approach offers a robust solution for mapping rice fields, particularly in regions with complex cropping landscapes, and enhances agricultural monitoring and decision-making processes contributing to sustainable rice production and food security initiatives. © 2024 Elsevier B.V.
BBRvl vs BBRv2: Examining Performance Differences through Experimental Evaluation
(IEEE Computer Society help@computer.org, 2020) Nandagiri, A.; Tahiliani, M.P.; Misra, V.; Ramakrishnan, K.K.
BBR, a congestion control algorithm proposed by Google, regulates the source sending rate by deriving an estimate of the bottleneck's available bandwidth and RTTof the path. The initial version of BBR, called BBRvl, was found to be unfair, getting higher than the fair share of bandwidth when co-existing on bottleneck links with other congestion control algorithms. It also does not perform as well with networks having routers with shallow buffers. To overcome these concerns, a newer version, called BBRv2, has been proposed. Our goal in this paper is to understand the differences between the two versions and examine the primary reasons behind the improvement in performance of BBRv2. We present an experimental evaluation of BBRvl and BBRv2, evaluating their fairness across connections using the same protocol (intra-protocol fairness) and using different protocols (inter-protocol fairness) as well as delay and link utilization. From experiments with shallow and deep buffers, BBRv2 is most effective when it uses Explicit Congestion Notification (ECN), but fairness issues continue to exist in BBRv2 when ECN is disabled. A concern for BBRv2 is that it is somewhat complex to deploy in Wide Area Networks (WAN) because of the dependency with the DCTCP-style reduction of the congestion window, which is primarily usable in low-feedback delay Data Center Networks. Â© 2020 IEEE.
BCON: Back pressure based congestion avoidance model for Named Data Networks
(2017) Agarwal, A.; Tahiliani, M.P.
Queue management in Named Data Networks (NDN) has gained a lot of attention recently. Unlike the traditional IP architecture, the transport mechanism in NDN is intricate and comprises of in-network caching of data packets at routers. Hence, the most effective avoidance of congestion can occur at the routers itself. In this paper, we make two contributions: first, we propose a back pressure based congestion avoidance model for NDN which leverages the benefits of Active Queue Management (AQM) mechanisms. Using this model, we apply the existing AQM mechanisms like Random Early Detection (RED), Adaptive RED (ARED), Controlled Delay (CoDel) and Proportional Integral controller Enhanced (PIE) in NDN. Second, we study the effectiveness of our proposed model by performing simulations using ndnSIM. Our simulation results indicate that the proposed model successfully balances the tradeoff between link utilization and Data drop rate. � 2016 IEEE.