Ensuring the reliability and availability of complex networked services demands effective root cause analysis (RCA) across cloud environments, data centers, and on-premises networks. Traditional RCA methods, which involve manual inspection of data sources such as logs and telemetry data, are often time-consuming and challenging for on-call engineers. While statistical inference methods have been employed to estimate the causality of network events, these approaches alone are similarly challenging and suffer from a lack of interpretability, making it difficult for engineers to understand the predictions made by black-box models. In this paper, we present RCACopilot, an advanced on-call system that combines statistical tests and large language model (LLM) reasoning to automate RCA across various network environments. RCACopilot gathers and synthesizes critical runtime diagnostic information, predicts the root cause of incidents, provides a clear explanatory narrative, and offers targeted action steps for engineers to resolve the issues. By utilizing LLM reasoning techniques and retrieval, RCACopilot delivers accurate and practical support for operators.

We address the problem of detecting non-transient anomalies in visual information. By non-transient anomalies we mean changes in the way environments look that are persistent across time. Such changes may include leaving unattended bags at airport corridors, putting graffiti in building walls or damaging public property. Detecting non-transient anomalies is critical to security and surveillance in indoor and outdoor environments. We argue that existing off-the-shelf solutions to computer vision problems (e.g., image recognition, gesture recognition, text recognition) are not the most efficient when applied to detecting non-transient anomalies due to their associated computational overhead. In this paper we present a neural network-based architecture that addresses some of the limitations of the state of the art. To speed up computations, our architecture supports the processing of a large number of neurons in parallel. To reduce computational overheads, our architecture omits some of the Gaussian kernel-based feature extraction tasks performed by other systems. To classify visual anomalies as non-transient, our architecture uses a codebook-based algorithm which builds a history profile for every image segment. We describe our architecture and present some performance analysis.

Packet scheduling is a critical component of router data paths because it allows routers to divide bandwidth intelligently between competing flows. A large number of scheduling algorithms annotate packets with time stamps and subsequently sort these packets according to their annotated time stamp values. For these algorithms the problems of efficiently tagging and sorting packets are still open to investigation. In this paper we propose a data structure and algorithm that reduces the latency of determining the packet with the smallest time stamp to a single memory access time and a small constant number of computation steps, independent of the number of flows serviced by the scheduler. The complexity of inserting a packet into our sorting data structure is logarithmic as a function of the ratio between the maximum packet size and minimum connection weight. The latency of inserting a packet can be hidden by performing insertions of several packets in parallel. This is the fastest sorting data structure known to us. One of the most efficient alternative implementation techniques proposed by Chao et. al. [20] is associated with logarithmic complexity of the scheduling decision time, as a function of the maximum value of packet time stamps. Our solution applies to many different packet fair queuing algorithms including Weighted Fair Queuing [28], Self-Clocked Fair Queuing (SCFQ) [28] and Start Time Fair Queuing [4].

Overhead of memory accesses limits the performance of packet processing applications. To overcome this bottleneck, today's network processors can utilize a wide-range of mechanisms-such as multi-level memory hierarchy, wide-word accesses, special-purpose result-caches, asynchronous memory, and hardware multi-threading. However, supporting all of these mechanisms complicates programmability and hardware design, and wastes systemresources. In this paper, we address the following fundamental question: what minimal set of hardware mechanisms must a network processor support to achieve the twin goals of simplified programmability and high packet throughput? We show that no single mechanism sufficies; the minimal set must include data-caches and multi-threading. Data-caches and multi-threading are complementary; whereas data-caches exploit locality to reduce the number of context-switches and the off-chip memory bandwidth requirement, multi-threading exploits parallelism to hide long cache-miss latencies.

In this study, we refute the popular belief [1,2] that packet processing does not benefit from data-caching. We show that a small data-cache of 8KB can bring down the packet processing time by much as 50-90%, while reducing the off-chip memory bandwidth usage by about 60-95%. We also show that, unlike general-purpose computing, packet processing, due to its memory-intensive nature, cannot rely exclusively on data-caching to eliminate the memory bottleneck completely.

Providing quality of service (QoS) in an efficient and scalable manner in the Internet is a topic of active research. The technologies that have drawn the most attention are integrated services (IntServ), differential services (DiffServ) and label switching (MPLS). While these technologies are orthogonal in many respects and can coexist, they are all similar with respect to the fact that some or all the routers in such networks need to be programmed with state information associating data flows with QoS classes or priorities or labels. This paper describes a protocol called SSP (state setup protocol) which is designed to disseminate and manage this state information. In addition to a simple design which makes fast implementations feasible, SSP provides many features like state aggregation and third party signaling which makes SSP a suitable tool for network configuration, management and provisioning as well. A detailed discussion of SSP is presented along with numerous examples and performance measurements.

No abstract available.

No abstract available.

This paper presents PCSMA, an extension to the CSMA/CD protocol (used in the Ethernet) to support both conventional datagram traffic and real-time traffic. The protocol provides predictable packet-delivery bounds for real-time traffic. It does not require changes to existing Ethernet controllers for datagram traffic. Under the new protocol, periodic sources follow a variation of the CSMA protocol that requires them to reserve transmission slots before they can begin transmission. This protocol is intended particularly for use in the integrated network in a manufacturing shop. Periodic sources include multiple sensors generating disparate types and rates of data. We have carried out an extensive performance evaluation of the protocol using a simulation model. The results are impressive: PCSMA shows fewer collisions than CSMA, equivalent delays for conventional traffic, and no failures to meet deadlines for periodic traffic.>

Efficient management of non-alphanumeric data (such as images, videos, and graphs) is essential to a large number of applications.This paper discusses the issues in pictorial information modeling, examines the suitability of traditional data modeling approaches, and then proposes a new objectoriented data modeling approach, called Modeling Object- Oriented Data Semantics (MOODS).A key idea in MOODS is to integrate the image processing component of an image information management system with the data modeling technique.In addition, a user may provide additional assistance in defining semantics at various stages.We argue that the data modeling technique must capture the sequence of transformations and allow a variety of semantics to be associated with the same data to accommodate different application domains.Additional salient features of MOODS include a notion of abstract function classes and dynamic binding of functions to data.

We are investigating alternative transport protocol strategies for realizing large scale dissemination services across a wide area network. Communication requirements of such applications are distinct from those based on conventional client-server interactions. Conventional flow and error control methods based on the retransmissions-with-timeout paradigm are not appropriate for such applications. Instead, we are interested in using optimistic flow and error control strategies that take into account application-specific error tolerance and media rates of multimedia applications. This paper describes transport level policies that use a combination of redundant transmissions, rate-based flow control, and selective feedback from receivers. A simulation-based performance evaluation demonstrates that relatively simple techniques succeed well in meeting the QOS requirements of a multimedia multicast and in scaling to hundreds of recipients. 1 Introduction Our research is motivated by the co...

The multiflow conversation protocol (MCP), which provides two communication abstractions is discussed. MCP provides a token-based mechanism for concurrency control among participants of a multipoint connection and includes a communication abstraction called a multiflow conversation. A conversation may consist of one or more connections, and MCP enforces temporal synchronization in the delivery of traffic over participant connections. Delivery of traffic in a conversation is also based on a notion of causality that takes into account the delay constraints associated with real-time traffic.>

An approach is described to network monitoring in which the end user can tailor the monitor to local needs. The system is extensible, allowing the user to specify what data one is interested in seeing, and how they should be displayed. While existing monitors understand only predefined packet types, the system described can be extended quickly and without source code changes to understand new protocols.>

A congestion avoidance and control scheme that monitors the incoming traffic to each destination and provides rate-based feedback information to the sources of bursty traffic so that sources of traffic can adjust their packet rates to match the network capacity is described. The congestion avoidance mechanism at nodes on the periphery of the network controls incoming traffic so that it does not exceed the capacity of paths to different destinations. The congestion control mechanism at each node monitors the performance of adjacent links and generates rate control messages that warn the sources of traffic before congestion develops. Some existing schemes are reviewed, and the congestion avoidance and control scheme and its applicability to various transport protocols are discussed. Experiments show that the scheme is effective in preventing congestion inside the network and that it manages to restrict the traffic on any overloaded path to 80%-90% of its capacity.>

A network-level communication abstraction called flow is discussed as a communication channel that has specific performance characteristics associated with its traffic. The underlying delivery system guarantees to meet performance requirements of a flow once it accepts a flow request. Upper layers use flows to implement transport-level protocols and high performance applications. The authors describe the concept of flows in detail and present algorithms that implement flows in a high-speed packet-switched network under development at Purdue University.>

The use of long-haul networks by the scientific community to access resources at supercomputing centers has created a need for high-level user services and tools to provide transparent and efficient access to remote resources. A way to provide a computational service for supercomputer access in a distributed environment is described. The issues involved in the design of such a service are discussed, and attention is focused on a remote job submission facility. A prototype implementation is also described.>