Analysis of IP Network Path Capacity Estimation Using a Variable Packet Size Method

Along with the times, the computer network has undergone many changes from time to time. Eventually, internet network is known. To test the reachability of a host on an IP address (internet protocol) network and to measure the round-trip time for messages sent from the host to the destination, computer needs to perform ping process. Ping operates by sending ICMP (Internet Control Message Protocol) echo request packets to the target host and waiting for an ICMP response. internet connection lane determination automation uses three providers done by comparing the smallest average value of the result of the ping. The test results are printed in the form of a statistical summary of the response packets received, including the minimum, maximum and average round-trip time. The signal strength is not directly proportional to the value of average, because the signal strength is affected by the report the data RSCP, throughput and quality of services covering CSSR (Call Setup Success Ratio), CCSR (Call Completion Success Ratio), DCR (Dropped Call Ratio) and BCR (Blocked Call Ratio) which can be used to optimize the network.

Grids offer the potential to carry out difficult computing tasks and achieve superior aggregate performance. However, grids are highly complex systems. They consist of heterogeneous resources on disparate hosts from various virtual organizations interconnected via a mixture of communication standards. Monitoring grid resources allows grid schedulers to adapt to changes in the status of these remote resources and the network paths between them. This is crucial to ensuring optimum performance. In this paper we introduce a distributed solution, called GridMAP, to collect network and end-host resource measurements, analyze their performance and feed these statistics and predictions back to schedulers. At this stage, we present our implementation of a passive TCP-SYN-based technique to provide GridMAP with round trip time and throughput measurements and we evaluate our approach against ping and iperf.

REDUP: a packet loss recovery scheme for real-time audio streaming over wireless IP networks

Assigning jobs to optimum resources in a grid environment is the main aim of a grid scheduler. Communication cost has always been an important issue in grid environments. Proposing new scheduling algorithms to consider this cost accurately and allocate jobs to an optimum resource efficiently has always been of great importance. In this paper we have proposed a grid scheduling algorithm that is aware of the costs for different network paths. We have also considered soft real-time characteristics of jobs in our proposed algorithm. We have simulated and compared our algorithm with some key scheduling algorithms such as Least Load First (LLF), Random, and First Come First Served (FCFS) in Gridsim by considering soft real-time jobs. Results show the superiority of our scheduling algorithm due to its ability to predict network cost and to satisfy the demands of soft real-time tasks.

Abstract. Modern mobile devices offer advanced capabilities for navigation and Location-Based Services (LBS). This study investigates the use of Ultra-Wideband (UWB) and Wi-Fi Round-Trip Time (RTT) measurements for pedestrian localization across various scenarios. We analyze the ranging accuracy of these techniques and evaluate positioning performance using different fusion algorithms. Our proposed collaborative positioning (CP) methodology enhances localization accuracy for user groups within a defined area. Results demonstrate significant improvements in position trueness, with UWB and Wi-Fi RTT achieving enhancements of 74% and 54%, respectively. Additionally, our localization algorithm, leveraging a Peer-to-Infrastructure (P2I) and Peer-to-Peer (P2P) hybrid configuration, increases anchor availability by up to 10%. Even in short-duration anchor loss scenarios (P2P-only), position trueness improves by up to 53%. These findings highlight the potential of UWB and Wi-Fi RTT in real-world pedestrian localization, particularly for urban navigation, smart mobility applications, and emergency response systems.

Effective monitoring of network utilization and performance indicators is a key enabling technology for proactive and reactive resource management, flexible accounting, and intelligent planning in next-generation IP networks. In this paper, we address the challenging problem of efficiently monitoring bandwidth utilization and path latencies in an IP data network. Unlike earlier approaches, our measurement architecture assumes a single point-of-control in the network (corresponding to the network operations center) that is responsible for gathering bandwidth and latency information using widely-deployed management tools, like SNMP, RMON/NetFlow, and explicitly-routed IP probe packets. Our goal is to identify effective techniques for monitoring (a) bandwidth usage for a given set of links or packet flows, and (b) path latencies for a given set of paths, while minimizing the overhead imposed by the management tools on the underlying production network. We demonstrate that minimizing overheads under our measurement model gives rise to new combinatorial optimization problems, most of which prove to be NP-hard. We also propose novel approximation algorithms for these optimization problems and prove guaranteed upper bounds on their worst-case performance. Our simulation results validate our approach, demonstrating the effectiveness of our novel monitoring algorithms over a wide range of network topologies.

Google proposed a new TCP congestion control algorithm (CCA), Bottleneck Bandwidth and Round-trip propagation time (BBR) which has opened up new dimensions in congestion control. BBR tries to operate near Kleinrock's operating point to avoid excessive queue formation at the bottleneck and to use the link bandwidth optimally. BBR creates a model of the network path by measuring the bottleneck bandwidth and minimum round-trip time (RTT) to maximize the delivery rate and minimize latency. BBR v2 is an updated version of BBR which addresses many shortcomings of the original BBR (BBR v1) such as interprotocol fairness, RTT fairness, and excessive retransmissions. However, BBR v2 has certain limitations in its operation in IEEE 802.11ac (Wi-Fi 5) networks. The default BBR v2 limits the throughput of Wi-Fi 5 and an increased latency has been observed. This is because the Wi-Fi 5 frame aggregation logic is underutilized and fewer frames are being sent to the Wi-Fi 5 interface. In this paper, we have proposed BBR-n (BBR new) which provides better throughput than the generic BBR v2 in the Wi-Fi 5 networks. Real-time experiments were performed over a physical testbed using Flent to confirm that BBR-n achieves over double throughput as compared to generic BBR v2 and reduced latency in networks as compared to pure loss-based variants such as Cubic and Reno.

Google proposed a new congestion control algorithm (CCA) based on bottleneck bandwidth and round-trip propagation time (BBR), which is considered to open a new era of congestion control. BBR creates a network path model by measuring the available bottleneck bandwidth and the minimum round-trip time (RTT) to maximize delivery rate and minimize latency. The BBR v2 algorithm is a recently updated version by Google, which aims to improve some of the problems in the original BBR (BBRv1) algorithm, such as interprotocol fairness issues, RTT fairness issues, and excessive retransmissions. The BBRv2 evaluation results show that it can improve the coexistence with the loss_based algorithm and alleviate some of the shortcomings in BBRv1. However, when multiple BBRv2 flows enter the same link at different times, fair convergence cannot be achieved, and RTT fairness still exists. Based on these problems, we analyze the root cause and proposed an improved algorithm BBRv2+, which uses flow-aware explicit congestion notification (ECN) to quantify queue information and feedback on the accurate congestion degree. BBRv2+ algorithm can avoid blind window constraints and selectively mark packets so that different flows can converge to fairness. In the simulation experiment of Network Simulator 3 (NS3), the results show that the BBRv2+ algorithm can improve intraprotocol fairness and RTT fairness and ensure bandwidth utilization and interprotocol fairness.

Path round-trip delay, i.e., path round-trip time (RTT), is one of the key metrics for evaluating network performance, also plays a crucial role in several overlay network construction protocols, peer-to-peer (P2P) applications, etc. In this paper, we present HPAP, a high precision active probe for path RTT measurement, which is based on Berkeley Packet Filter (BPF) technology. When the measuring probe packets arrive at or depart from the Network Interface Card (NIC), the BPF can capture them quickly, and can mark the timestamps immediately. The HPAP can calculate the path RTT value according to these timestamps. By this method, the time-stamp position can be removed from application program to data link layer of TCP/IP stack. The experimental results show that the new scheme can nearly eliminate the location error, and can practically improve the path RTT measuring accuracy. This scheme has low-cost in the investment, so it can be applied widely.

5G NR mm Wave promises accurate positioning down to the centimeter level. However, mmWave signals endure prismatic propagation, making them prone to signal blockages and non-line of sight (NLoS) communications. To achieve a precise positioning solution, it is rather essential to filter out NLoS gNBs as they yield erroneous pose estimation of IoT vehicular applications. Previous works have attempted to address this issue, however, they are either based on impractical or invalid assumptions about the operation scenario. In this paper, a novel, yet, simple and realistic NLoS detection algorithm is developed. The proposed method measures the discrepancy between Received Signal Strength (RSS)-based and time-based ranges as means to detect NLoS operation. To validate the proposed NLoS detection method, it was incorporated into a Kalman Filter (KF) that fuses the angle of departure (AoD) and round trip time (RTT) measurements from multiple gNBs in a loosely coupled fashion. The proposed method was evaluated on quasi-real measurements acquired from a highly validated 5G simulation tool that simulates the cores of downtown Toronto. The proposed method demonstrates superior results, as it sustains a sub-1m level of accuracy for around 95% of the time, as compared to merely 29% of the time without the NLoS detection.

This paper provides a preliminary investigation into the impact a link with changing propagation delay has on the performance of TCP file transfers. We investigate over a dozen different variable delay patterns, based on spacecraft movement. We highlight the performance impact of such variability, paying close attention to TCP's retransmission timer, which is based on the observed round-trip time of the network path. In addition, we explore one scenario in which the round-trip time across a network path suddenly changes due to a large change in the path between the two end-points. We conclude that the variable delay network paths studied in this paper do not drastically impact TCP performance.

Hybrid routing approaches which either combine the best of traditional IGP and MPLS routing or allow a smooth migration from traditional IGP routing to the newly proposed MPLS standard have scarcely been addressed by the IP community. This paper presents an on-line traffic engineering (TE) model which uses a hybrid routing approach to achieve efficient routing of flows in IP networks. The model assumes a network-design process where the IP flows are classified at the ingress of the network and handled differently into the core using a multiple metric routing mechanism leading to the logical separation of a physical network into two virtual networks: An IGP network carrying low bandwidth demanding (LBD) flows and an MPLS network where bandwidth-guaranteed tunnels are setup to route high bandwidth demanding (HBD) flows. The hybrid routing approach uses a route optimization model where (1) link weight optimization (LWO) is implemented in the IGP network to move the IP flows away from links that provide a high probability to become bottleneck for traffic engineering and (2) the MPLS network is engineered to minimize the interference among competing flows and route the traffic away from heavily loaded links. We show that a cost-based optimization framework can be used by an ISP to design simple and flexible routing approaches where different metrics reflecting the ISP's view of its TE objectives are deployed to improve the use and efficiency of a network. This is achieved through extensions to a mixed cost metric derived from the route optimization model. The IGP+MPLS routing approach is applied to compute paths for the traffic offered to a 15- and 50-node network. Preliminary simulation reveals performance improvements compared to both IGP and MPLS routing in terms of the routing optimality and the network reliability.

In these days, IP network customers become sensitive to the QoS guarantee provided by the network. Amongst many QoS guarantee schemes, Diffserv (Differentiated Services) is the one of the most practical candidates for the next generation IP networks. Under these circumstances, the commercial network venders have already provided the Diffserv routers that support EF (Expedited Forwarding) PHB (Per Hop Behavior). However, AF (Assured Forwarding) PHB in Diffserv still has not been provided by commercial routers. Therefore, it is a realistic solution that SBR3 (Statistical Bit Rate 3) of ATM emulates AF PHB, but it is not clear whether TCP traffic over AF PHB emulated by ATM is differentiated from the best effort TCP traffic over DF (Default Forwarding) PHB. To confirm the differentiation, we have experimentally studied TCP performance through the link into which TCP connections over AF PHB and DF PHB are aggregated. This paper describes the experimental results and discusses the possibility of the TCP performance differentiation between AF PHB and DF PHB over ATM.

The General Packet Radio Service (GPRS) is being deployed by GSM network operators world-wide, and promises to provide users with “always-on” data access at bandwidths comparable to that of conventional fixed-wire telephone modems. However, many users have found the reality to be rather different, experiencing very disappointing performance when, for example, browsing the web over GPRS. In this paper, we examine the causes, and show how unfortunate interactions between the GPRS link characteristics and TCP/IP protocols lead to poor performance. A performance characterization of the GPRS link-layer is presented, determined through extensive measurements taken over production networks. We present measurements of packet loss rates, bandwidth availability, link stability, and roundtrip time. The effect these characteristics have on TCP behavior are examined, demonstrating how they can result in poor link utilization, excessive packet queueing, and slow recovery from packet losses. Further, we show that the HTTP protocol can compound these issues, leading to dire WWW performance. We go on to show how the use of a transparent proxy interposed near the wired-wireless border can be used to alleviate many of these performance issues without requiring changes to either client or server end systems.

We propose the first practical solution to the longstanding problem of secure wireless routing in the presence of colluding attackers. Our secure routing protocol, Sprout, continuously tries new routes to the destination. Routes are probabilistically generated, with complete disregard for performance metrics. This makes Sprout uniquely resilient to attack: it cannot be tempted by shortcuts. In order to avoid compromised routes, and to ensure good overall performance, the quality of each active route is monitored by means of signed end-to-end acknowledgments. The amount of traffic sent on each route is adjusted accordingly. Sprout effectively mitigates the vast majority of known routing layer attacks, even when under assault from a large number of colluding attackers. Experiments on our 31-node testbed demonstrates the real-world performance of Sprout in terms of packet delivery ratio, round-trip times and TCP throughput. Our security analysis and simulation results show that Sprout is able to quickly find working paths in networks of hundreds of nodes and dozens or more attackers. For example, in a network of 200 nodes and an astounding 64 attackers, Sprout, on average, found a successful route within less than 10 attempts. Yet, in benign settings, Sprout provides TCP throughput within 15% of the shortest path throughput Overall, Sprout consistently delivers high, reliable performance in benign as well as hostile environments.