The document describes using the Network Simulator 2 (NS2) tool to simulate network scenarios. NS2 is an open-source discrete event network simulator for Linux. The document outlines installing and configuring NS2, including applying a patch to add support for the Stream Control Transmission Protocol (SCTP). It then describes two simulation scenarios using NS2: one monitors SCTP traffic between two nodes transferring FTP data, the other looks at web traffic over six nodes using TCP. Graphs of the SCTP simulation show transmitted packets and bandwidth utilization.
As containers are being deployed as part of multi tenant clusters, virtual multi layer switches become essential to interconnect containers while providing isolation guarantees. Assigning tenants their own private networks requires stateful network address translation (NAT) implemented in a scalable architecture to expose containers to public networks. Existing virtual switches integrated into the Linux kernel did not support stateful NAT so far. This presentation introduces a new virtual NAT service deployable as container built using existing kernel functionality such as network namespaces, routing rules and Netfilter to provide NAT services to existing virtual switches such as Open vSwitch and the Linux bridge but also the core L3 layer of Linux.
In this talk we discuss the mechanisms of utilizing the eBPF language to perform hardware accelerated network packet manipulation and filtering. P4 programs can be compiled into eBPF scripts for offload in the Linux kernel using the Traffic Classifier (TC) subsystem. We demonstrate how, using eBPF as an intermediate language, it has been possible to extend the TC to either Just In Time (JIT) compile eBPF code to x86 assembler for software offload or to IXP byte code for execution in a trusted hardware environment within the Netronome Agilio intelligent server adapter. We finish by encouraging the audience to experiment with their own eBPF applications within the TC hardware accelerated system. The TC kernel patches are available on the Linux Kernel Networking mailing list as a Request For Comment (RFC) contribution.
Dinan Gunawardena, Director, Software Engineering, Netronome
Dinan Gunawardena is a Software Director focusing on running the driver team at Netronome. Previously, Dinan founded a software startup and was a Senior Research Engineer within the Operating Systems and Networking Group at Microsoft Research for 12 years, shipping technology in several versions of Microsoft Windows and the Bing Search Engine. Dinan has received over 20 patents and is a Chartered Software Engineer. Dinan has a Masters in Computer Science from University of Cambridge and a M.B.A. from WBS.
Jakub Kicinski, Software Engineering, Netronome
Jakub Kicinski is a Software Engineer specializing in the Linux Kernel drivers for Netronome SmartNICs. Jakub has previously worked as an intern for Intel Corporation. Jakub is also a researcher with expertise in Linux kernel. Experience in application development on complex multi-CPU and FPGA platforms. He is interested in high-performance software exploiting hardware capabilities and is passionate about networking. Jakub has a Masters in Computer Science from Gdansk University of Technology.
In this session, weโll review how previous efforts, including Netfilter, Berkley Packet Filter (BPF), Open vSwitch (OVS), and TC, approached the problem of extensibility. Weโll show you an open source solution available within the Red Hat Enterprise Linux kernel, where extending and merging some of the existing concepts leads to an extensible framework that satisfies the networking needs of datacenter and cloud virtualization.
As containers are being deployed as part of multi tenant clusters, virtual multi layer switches become essential to interconnect containers while providing isolation guarantees. Assigning tenants their own private networks requires stateful network address translation (NAT) implemented in a scalable architecture to expose containers to public networks. Existing virtual switches integrated into the Linux kernel did not support stateful NAT so far. This presentation introduces a new virtual NAT service deployable as container built using existing kernel functionality such as network namespaces, routing rules and Netfilter to provide NAT services to existing virtual switches such as Open vSwitch and the Linux bridge but also the core L3 layer of Linux.
In this talk we discuss the mechanisms of utilizing the eBPF language to perform hardware accelerated network packet manipulation and filtering. P4 programs can be compiled into eBPF scripts for offload in the Linux kernel using the Traffic Classifier (TC) subsystem. We demonstrate how, using eBPF as an intermediate language, it has been possible to extend the TC to either Just In Time (JIT) compile eBPF code to x86 assembler for software offload or to IXP byte code for execution in a trusted hardware environment within the Netronome Agilio intelligent server adapter. We finish by encouraging the audience to experiment with their own eBPF applications within the TC hardware accelerated system. The TC kernel patches are available on the Linux Kernel Networking mailing list as a Request For Comment (RFC) contribution.
Dinan Gunawardena, Director, Software Engineering, Netronome
Dinan Gunawardena is a Software Director focusing on running the driver team at Netronome. Previously, Dinan founded a software startup and was a Senior Research Engineer within the Operating Systems and Networking Group at Microsoft Research for 12 years, shipping technology in several versions of Microsoft Windows and the Bing Search Engine. Dinan has received over 20 patents and is a Chartered Software Engineer. Dinan has a Masters in Computer Science from University of Cambridge and a M.B.A. from WBS.
Jakub Kicinski, Software Engineering, Netronome
Jakub Kicinski is a Software Engineer specializing in the Linux Kernel drivers for Netronome SmartNICs. Jakub has previously worked as an intern for Intel Corporation. Jakub is also a researcher with expertise in Linux kernel. Experience in application development on complex multi-CPU and FPGA platforms. He is interested in high-performance software exploiting hardware capabilities and is passionate about networking. Jakub has a Masters in Computer Science from Gdansk University of Technology.
In this session, weโll review how previous efforts, including Netfilter, Berkley Packet Filter (BPF), Open vSwitch (OVS), and TC, approached the problem of extensibility. Weโll show you an open source solution available within the Red Hat Enterprise Linux kernel, where extending and merging some of the existing concepts leads to an extensible framework that satisfies the networking needs of datacenter and cloud virtualization.
Kernel Recipes 2017 - EBPF and XDP - Eric LeblondAnne Nicolas
ย
Berkeley Packet Filter is an old friend for most people that deal with network under Linux. But its extended version eBPF is completely redefining the scope of usage and interaction with the kernel. It can indeed be used to instrument most parts of the kernel. This goes from network tracing to process or I/O monitoring.
This talk will provide an overview of eBPF, from concept to tools like BCC. It will then focus on XDP for eXtreme Data Path and the possible applications in term of networking provided by this new framework.
Eric Leblond, Stamus Network
Cilium - Fast IPv6 Container Networking with BPF and XDPThomas Graf
ย
We present a new open source project which provides IPv6 networking for Linux Containers by generating programs for each individual container on the fly and then runs them as JITed BPF code in the kernel. By generating and compiling the code, the program is reduced to the minimally required feature set and then heavily optimised by the compiler as parameters become plain variables. The upcoming addition of the Express Data Plane (XDP) to the kernel will make this approach even more efficient as the programs will get invoked directly from the network driver.
Opensample: A Low-latency, Sampling-based Measurement Platform for Software D...Junho Suh
ย
In this paper we propose, implement and evaluate OpenSample: a low-latency, sampling-based network measure- ment platform targeted at building faster control loops for software-defined networks. OpenSample leverages sFlow packet sampling to provide nearโreal-time measurements of both net- work load and individual flows. While OpenSample is useful in any context, it is particularly useful in an SDN environment where a network controller can quickly take action based on the data it provides. Using sampling for network monitoring allows OpenSample to have a 100 millisecond control loop rather than the 1โ5 second control loop of prior polling-based approaches. We implement OpenSample in the Floodlight OpenFlow controller and evaluate it both in simulation and on a testbed comprised of commodity switches. When used to inform traffic engineering, OpenSample provides up to a 150% throughput improvement over both static equal-cost multi-path routing and a polling-based solution with a one second control loop.
BPF of Berkeley Packet Filter mechanism was first introduced in linux in 1997 in version 2.1.75. It has seen a number of extensions of the years. Recently in versions 3.15 - 3.19 it received a major overhaul which drastically expanded it's applicability. This talk will cover how the instruction set looks today and why. It's architecture, capabilities, interface, just-in-time compilers. We will also talk about how it's being used in different areas of the kernel like tracing and networking and future plans.
Frank Ham from Cascade Technologies presented this deck at the Stanford HPC Conference.
"A spin-off of the Center for Turbulence Research at Stanford University, Cascade Technologies grew out of a need to bridge between fundamental research from institutions like Stanford University and its application in industries. In a continual push to improve the operability and performance of combustion devices, high-fidelity simulation methods for turbulent combustion are emerging as critical elements in the design process. Multiphysics based methodologies can accurately predict mixing, study flame structure and stability, and even predict product and pollutant concentrations at design and off-design conditions."
Watch the video: http://insidehpc.com/2017/02/best-practices-large-scale-multiphysics/
Learn more: http://www.cascadetechnologies.com
and
http://www.hpcadvisorycouncil.com/events/2017/stanford-workshop/
Sign up for our insideHPC Newsletter: http:/insidehpc.com/newsletter
Cilium - API-aware Networking and Security for Containers based on BPFThomas Graf
ย
Cilium is open source software for providing and transparently securing network connectivity and loadbalancing between application workloads such as application containers or processes. Cilium operates at Layer 3/4 to provide traditional networking and security services as well as Layer 7 to protect and secure use of modern application protocols such as HTTP, gRPC and Kafka. Cilium is integrated into common orchestration frameworks such as Kubernetes and Mesos.
Designing HPC & Deep Learning Middleware for Exascale Systemsinside-BigData.com
ย
DK Panda from Ohio State University presented this deck at the 2017 HPC Advisory Council Stanford Conference.
"This talk will focus on challenges in designing runtime environments for exascale systems with millions of processors and accelerators to support various programming models. We will focus on MPI, PGAS (OpenSHMEM, CAF, UPC and UPC++) and Hybrid MPI+PGAS programming models by taking into account support for multi-core, high-performance networks, accelerators (GPGPUs and Intel MIC), virtualization technologies (KVM, Docker, and Singularity), and energy-awareness. Features and sample performance numbers from the MVAPICH2 libraries will be presented."
Watch the video: http://wp.me/p3RLHQ-glW
Learn more: http://hpcadvisorycouncil.com
Sign up for our insideHPC Newsletter: http://insidehpc.com/newsletter
Presentation of Mr.Vibin Chander, CEO, Shabari Software Solutions, CBE. Delivered during the Faculty development Program on NS2 organized by Department of Computer Science, Rathinam College of Arts and Science (Autonomous), Eachanari, Coimbatore - 641021.
The goal of the project โAn opticโs lifeโ is, to predict the time when an optical transceiver will reach its real end-of-life-time based on the actual setup in the datacenter / colocation.
Kernel Recipes 2017 - EBPF and XDP - Eric LeblondAnne Nicolas
ย
Berkeley Packet Filter is an old friend for most people that deal with network under Linux. But its extended version eBPF is completely redefining the scope of usage and interaction with the kernel. It can indeed be used to instrument most parts of the kernel. This goes from network tracing to process or I/O monitoring.
This talk will provide an overview of eBPF, from concept to tools like BCC. It will then focus on XDP for eXtreme Data Path and the possible applications in term of networking provided by this new framework.
Eric Leblond, Stamus Network
Cilium - Fast IPv6 Container Networking with BPF and XDPThomas Graf
ย
We present a new open source project which provides IPv6 networking for Linux Containers by generating programs for each individual container on the fly and then runs them as JITed BPF code in the kernel. By generating and compiling the code, the program is reduced to the minimally required feature set and then heavily optimised by the compiler as parameters become plain variables. The upcoming addition of the Express Data Plane (XDP) to the kernel will make this approach even more efficient as the programs will get invoked directly from the network driver.
Opensample: A Low-latency, Sampling-based Measurement Platform for Software D...Junho Suh
ย
In this paper we propose, implement and evaluate OpenSample: a low-latency, sampling-based network measure- ment platform targeted at building faster control loops for software-defined networks. OpenSample leverages sFlow packet sampling to provide nearโreal-time measurements of both net- work load and individual flows. While OpenSample is useful in any context, it is particularly useful in an SDN environment where a network controller can quickly take action based on the data it provides. Using sampling for network monitoring allows OpenSample to have a 100 millisecond control loop rather than the 1โ5 second control loop of prior polling-based approaches. We implement OpenSample in the Floodlight OpenFlow controller and evaluate it both in simulation and on a testbed comprised of commodity switches. When used to inform traffic engineering, OpenSample provides up to a 150% throughput improvement over both static equal-cost multi-path routing and a polling-based solution with a one second control loop.
BPF of Berkeley Packet Filter mechanism was first introduced in linux in 1997 in version 2.1.75. It has seen a number of extensions of the years. Recently in versions 3.15 - 3.19 it received a major overhaul which drastically expanded it's applicability. This talk will cover how the instruction set looks today and why. It's architecture, capabilities, interface, just-in-time compilers. We will also talk about how it's being used in different areas of the kernel like tracing and networking and future plans.
Frank Ham from Cascade Technologies presented this deck at the Stanford HPC Conference.
"A spin-off of the Center for Turbulence Research at Stanford University, Cascade Technologies grew out of a need to bridge between fundamental research from institutions like Stanford University and its application in industries. In a continual push to improve the operability and performance of combustion devices, high-fidelity simulation methods for turbulent combustion are emerging as critical elements in the design process. Multiphysics based methodologies can accurately predict mixing, study flame structure and stability, and even predict product and pollutant concentrations at design and off-design conditions."
Watch the video: http://insidehpc.com/2017/02/best-practices-large-scale-multiphysics/
Learn more: http://www.cascadetechnologies.com
and
http://www.hpcadvisorycouncil.com/events/2017/stanford-workshop/
Sign up for our insideHPC Newsletter: http:/insidehpc.com/newsletter
Cilium - API-aware Networking and Security for Containers based on BPFThomas Graf
ย
Cilium is open source software for providing and transparently securing network connectivity and loadbalancing between application workloads such as application containers or processes. Cilium operates at Layer 3/4 to provide traditional networking and security services as well as Layer 7 to protect and secure use of modern application protocols such as HTTP, gRPC and Kafka. Cilium is integrated into common orchestration frameworks such as Kubernetes and Mesos.
Designing HPC & Deep Learning Middleware for Exascale Systemsinside-BigData.com
ย
DK Panda from Ohio State University presented this deck at the 2017 HPC Advisory Council Stanford Conference.
"This talk will focus on challenges in designing runtime environments for exascale systems with millions of processors and accelerators to support various programming models. We will focus on MPI, PGAS (OpenSHMEM, CAF, UPC and UPC++) and Hybrid MPI+PGAS programming models by taking into account support for multi-core, high-performance networks, accelerators (GPGPUs and Intel MIC), virtualization technologies (KVM, Docker, and Singularity), and energy-awareness. Features and sample performance numbers from the MVAPICH2 libraries will be presented."
Watch the video: http://wp.me/p3RLHQ-glW
Learn more: http://hpcadvisorycouncil.com
Sign up for our insideHPC Newsletter: http://insidehpc.com/newsletter
Presentation of Mr.Vibin Chander, CEO, Shabari Software Solutions, CBE. Delivered during the Faculty development Program on NS2 organized by Department of Computer Science, Rathinam College of Arts and Science (Autonomous), Eachanari, Coimbatore - 641021.
The goal of the project โAn opticโs lifeโ is, to predict the time when an optical transceiver will reach its real end-of-life-time based on the actual setup in the datacenter / colocation.
Small HPC clusters are widely used in many small labs since they are easy to build and cost-effective. When more power is needed, instead of adding costly new nodes to old clusters, we may try to make use of the idle times of some servers in the same building, that work independently for their own purposes, especially during the night. However such extension across a firewall raises not only some security
problem but also a load balancing problem caused by heterogeneity of the resulting system. In this paper,
we devise a method to solve such problems using only old techniques applicable to our old cluster systems
as is, without requiring any upgrade for hardware or software. We also discuss about how to deal with heterogeneity and load balancing in application, using a two-queue overflow queuing network problem as a sample problem.
Pushing Packets - How do the ML2 Mechanism Drivers Stack UpJames Denton
ย
Architecting a private cloud to meet the use cases of its users can be a daunting task. How do you determine which of the many L2/L3 Neutron plugins and drivers to implement? Does network performance outweigh reliability? Are overlay networks just as performant as VLAN networks? The answers to these questions will drive the appropriate technology choice.
In this presentation, we will look at many of the common drivers built around the ML2 framework, including LinuxBridge, OVS, OVS+DPDK, SR-IOV, and more, and will provide performance data to help drive decisions around selecting a technology that's right for the situation. We will discuss our experience with some of these technologies, and the pros and cons of one technology over another in a production environment.
Similar to Network simulator 2 a simulation tool for linux (20)
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
ย
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdfPaige Cruz
ย
Monitoring and observability arenโt traditionally found in software curriculums and many of us cobble this knowledge together from whatever vendor or ecosystem we were first introduced to and whatever is a part of your current companyโs observability stack.
While the dev and ops silo continues to crumbleโฆ.many organizations still relegate monitoring & observability as the purview of ops, infra and SRE teams. This is a mistake - achieving a highly observable system requires collaboration up and down the stack.
I, a former op, would like to extend an invitation to all application developers to join the observability party will share these foundational concepts to build on:
Climate Impact of Software Testing at Nordic Testing DaysKari Kakkonen
ย
My slides at Nordic Testing Days 6.6.2024
Climate impact / sustainability of software testing discussed on the talk. ICT and testing must carry their part of global responsibility to help with the climat warming. We can minimize the carbon footprint but we can also have a carbon handprint, a positive impact on the climate. Quality characteristics can be added with sustainability, and then measured continuously. Test environments can be used less, and in smaller scale and on demand. Test techniques can be used in optimizing or minimizing number of tests. Test automation can be used to speed up testing.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
ย
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
ย
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
ย
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
DevOps and Testing slides at DASA ConnectKari Kakkonen
ย
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Dev Dives: Train smarter, not harder โ active learning and UiPath LLMs for do...UiPathCommunity
ย
๐ฅ Speed, accuracy, and scaling โ discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Miningโข:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing โ with little to no training required
Get an exclusive demo of the new family of UiPath LLMs โ GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
๐จโ๐ซ Andras Palfi, Senior Product Manager, UiPath
๐ฉโ๐ซ Lenka Dulovicova, Product Program Manager, UiPath
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
ย
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
ย
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
ย
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
Generative AI Deep Dive: Advancing from Proof of Concept to ProductionAggregage
ย
Join Maher Hanafi, VP of Engineering at Betterworks, in this new session where he'll share a practical framework to transform Gen AI prototypes into impactful products! He'll delve into the complexities of data collection and management, model selection and optimization, and ensuring security, scalability, and responsible use.
Generative AI Deep Dive: Advancing from Proof of Concept to Production
ย
Network simulator 2 a simulation tool for linux
1. ๋ค์ด๋ฒ :: ๋ง์๊น์ง ํจ๊ปํ๋ ๋ค์ด๋ฒ ์นดํ ํ์ด์ง 1 / 8
์นดํiN ์ถ๋ ฅํ๊ธฐ | ์ฐฝ ๋ซ๊ธฐ
Network Simulator 2: a Simulation Tool for Linux | .. Network Simulator 2 2005.09.11 19:37
ํ๊ธธ๋(whitekamvo) http://cafe.naver.com/prognara/1
Network Simulator 2: a Simulation Tool for Linux
By Ibrahim Haddad and David Gordon on Mon, 2002-10-21 01:00. Software
Using Network Simulator 2 to simulate case scenarios using SCTP and TCP protocols with FTP and HTTP traffi
c.
The ARIES (Advanced Research on Internet E-Servers) Project started in 2000 as part of the Open Systems La
b research activities at the Ericsson Corporate Unit of Research. Initially, the project aimed to find and prototyp
e the necessary technology to prove the feasibility of an internet server that had the guaranteed availability, res
ponse time and scalability using Linux and open-source software. The project was successful, and it continued
in 2001 to focus on enhancing the clustering capabilities of Linux to be the operating system of choice for the
Mobile Internet servers. Many enhancements were added in the areas of load balancing, traffic distribution and
security, in addition to IPv6 support.
One interesting question that came up was what is the impact of supporting IPv6 on other protocols used by dif
ferent applications on our Linux clusters? To answer this question, we started a study investigating the effects o
f IPv6 support on other protocols, such as SCTP. Part of the study is to test applications in SCTP over IPv6. Ho
wever, we did not have the time and resources to set up a lab with multiple nodes and applications that use SC
TP over IPv6. Instead, we chose the next best solution, network simulation.
There is a growing recognition within different internet communities of the importance of simulation tools that h
elp design and test new internet protocols. New services and protocols present challenges for testing. For insta
nce, quality of service and multicast delivery require large and complex environments. Protocol designers recog
nize the advantages of simulation when computing resources are not available or are too expensive to duplicat
e a real lab setup. With simulation, you can do large-scale tests that are controlled and reproducible. This was
exactly what we needed to build our case scenarios; the search started primarily for an open-source tool becau
se most of our work targets the deployment of open-source software based on Linux.
Our target application is a real-time network simulation tool that we can use to define the different scenarios. A
very interesting open-source tool we came across was Network Simulator 2 (NS2), which was developed by the
Information Sciences Institute at the University of Southern California.
In this article, we summarize how to install and configure NS2 and look at two different simulation scenarios. T
he first scenario involves monitoring SCTP traffic between two nodes, and the second scenario looks at the beh
avior of web traffic and web applications over TCP over a six-node network.
The Tool: Network Simulator 2
NS2 is an open-source simulation tool that runs on Linux. It is a discreet event simulator targeted at networking
research and provides substantial support for simulation of routing, multicast protocols and IP protocols, such
as UDP, TCP, RTP and SRM over wired and wireless (local and satellite) networks. It has many advantages tha
t make it a useful tool, such as support for multiple protocols and the capability of graphically detailing network
traffic. Additionally, NS2 supports several algorithms in routing and queuing. LAN routing and broadcasts are p
art of routing algorithms. Queuing algorithms include fair queuing, deficit round-robin and FIFO.
NS2 started as a variant of the REAL network simulator in 1989 (see Resources). REAL is a network simulator o
riginally intended for studying the dynamic behavior of flow and congestion control schemes in packet-switche
d data networks.
Currently NS2 development by VINT group is supported through Defense Advanced Research Projects Agency
(DARPA) with SAMAN and through NSF with CONSER, both in collaboration with other researchers including AC
IRI (see Resources). NS2 is available on several platforms such as FreeBSD, Linux, SunOS and Solaris. NS2 al
so builds and runs under Windows.
Simple scenarios should run on any reasonable machine; however, very large scenarios benefit from large amo
unts of memory. Additionally, NS2 requires the following packages to run: Tcl release 8.3.2, Tk release 8.3.2,
OTcl release 1.0a7 and TclCL release 1.0b11.
Installation and Configuration
The process of installing NS2 is straightforward yet lengthy. At the time of writing, the most recent version was
2.1b8. We are interested in the "all-in-one" package because it includes the source code that we want to patc
h in SCTP support.
http://cafe.naver.com/ArticlePrint.nhn?clubid=11416022&articleid=1 2006-11-15
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You can download the all-in-one package from the NS2 home page (see Resources) into /usr/src and extract i
t as follows:
cd /usr/src
tar xzvf ns-allinone-2.1b8.tar.gz
cd ns-allinone-2.1b8
Because we want to examine a case scenario involving SCTP, we need to apply the SCTP patch to NS2 from t
he University of Delaware. The patch is available for the NS2 all-in-one 2.1b8 version and can be downloaded
from the Protocol Engineering Lab home page (see Resources). With the Linux patch utility, you can update the
NS2 source code to include support for SCTP by applying the patch:
patch -p0 < ns-allinone-2.1b8.sctp-rel2.2_patch_orig
In the same directory, there is a script named install that will configure, compile and install the required and opt
ional NS2 components. There is no interaction with the user while installing; the script is completely automated.
You must execute the script as superuser so that installation of binaries will be completed:
./install
When the installation process is complete, the following message will appear on your shell
Please put
$CUR_PATH/bin:$CUR_PATH/tcl$TCLVER/unix:$CUR_PATH/
tk$TKVER/unix into your PATH environment; so that
you'll be able to run itm/tclsh/wish/xgraph.
IMPORTANT NOTICES: [...]
Carefully follow all instructions given in the notices. The above-mentioned variables can be updated either by e
diting /etc/profile or changing environment variables directly. In case you updated /etc/profile, you need to sou
rce your new environment for the changes to take effect (i.e., source /etc/profile).
The NS2 validation suite will verify that all protocols are functional. This will fail if the install process was not co
mpleted; however, running validation is optional, and it consumes twice as much time as the compilation and i
nstallation process.
To run the validation suite:
cd ./ns-2.1b8
./validate
Using NS2 to Monitor SCTP Traffic
SCTP is a transmission protocol that was introduced by the IETF workgroup SIGTRAN in October 2000 (RFC 29
60) to allow SS7 traffic over IP. However, since then it has adopted many more uses because of its versatility a
s it also supports multihoming, network congestion control, error-free sequenced delivery and many other optio
ns.
After applying the SCTP patch to NS2 package, a README file is created: /usr/src/ns-allinone-2.1b8/ns-2.1b
8/sctp.README. At the end of the sctp.README file, there is an example script for an SCTP interaction. In the
simulation generated by this Tcl script, you will observe SCTP's four-way handshake as described in RFC 296
0, as well as congestion control. This scenario examines FTP traffic over SCTP between two nodes: node 0 is
FTP client and node 1 is FTP server.
The original script is hard coded for version 2.1b7a. You need to update few lines to reflect your own setup. Lis
ting 1 has been updated assuming that NS2 version 2.1b8 was installed.
Listing 1. SCTP Simulation Script
The changes that were applied to the original script are basically setting the paths depending on the specific en
vironment. Once you update the paths of all used tools, you are ready to start NS2 for a network simulation of
SCTP. To start the simulation, follow these steps:
cd /usr/src/ns-allinone-2.1b8
ns ./sctp.tcl
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Figure 1. SCTP Data Profile
Figure 2. Simulation Window
On execution, three windows will appear. The first window is represented by Figure 1 showing a graph with pac
ket traffic. The second window shows the simulation window as seen in Figure 2. The third window is the contr
ol window of the network animator (NAM).
It is interesting to see the graph generated by NS2 (Figure 1). The yellow x represents a dropped packet and ho
rizontally to the right is the retransmission. This dropped packet occurred because of an error loss model that
was introduced into the script that simply drops the specified packets between nodes given. SCTP manages ret
ransmission similarly to TCP, supporting fast retransmit.
set err [new ErrorModel/List]
$err droplist {15}
$ns lossmodel $err $n0 $n1
In the simulation window (Figure 2), right click on the link between both nodes and select graph --> graph ban
dwidth, and then click on Link 0-->1; you will obtain a bar graph representing bandwidth going from node 0 to
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node 1. You can repeat this process for reverse traffic bandwidth to monitor traffic going from node 1 to node
0. Now, you should see traffic bandwidth graphs below node display (Figure 3).
Figure 3. Traffic Bandwidth Utility Graphs
Before we start the scenario, we will take a brief look at some important lines in the script and explain what the
y do:
[...] // After initializing trace
// files and simulation windows
set n0 [$ns node] // two nodes are created
set n1 [$ns node] // (n0 and n1)
$ns duplex-link $n0 $n1 .5Mb 300ms DropTail
// then they are linked
// together
$ns duplex-link-op $n0 $n1 orient right
[...]
set sctp0 [new Agent/SCTP]
$ns attach-agent $n0 $sctp0
[...]
set sctp1 [new Agent/SCTP]
$ns attach-agent $n1 $sctp1
Then we define the protocol (SCTP) that will be used for destination and return traffic. An agent, defining what
protocol to use, is similar to a carrier for packets. Each agent must be attached to a specific node:
$ns connect $sctp0 $sctp1 // connect both agents
// together to set up
// a communications
// channel, or a stream
[...]
set ftp0 [new Application/FTP] // define the type of
// application that
// will use the
// stream, FTP
$ftp0 attach-agent $sctp0
To start real-time simulation, press the play forward button. The first event to notice is the four packets that init
iate the FTP connection. This corresponds to the stream initiation behavior specified in RFC 2960. The other ev
ent to observe is congestion control. SCTP will send few packets at a time and steadily increase until it reaches
a maximum throughput but will not flood the network. Although we do not alter our network's bandwidth, the FT
P connection between nodes 0 and 1 shows some basic congestion control. The beginning and end of the FTP
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connection are defined on these lines:
$ns at 0.5 "$ftp0 start"
$ns at 4.5 "$ftp0 stop"
Notice how the packets are being sent in an increasing fashion, or visually, in longer formats. Actually, the pac
kets are always the same length; however, the number of packets received by the server is increased as can be
seen by the number of SACKS received by client (Figure 4). SACKS are sent to acknowledge each packet recei
ved to ensure packet validation and reliability.
Figure 4. SACKS for Every SCTP Packet Sent
The University of Delaware did not implement multihoming in their SCTP patch to NS2. This means that SCTP b
ehaves similarly to TCP when it comes to streams. Otherwise, packets could be seen traveling both along the p
rimary path and along another routing path to the server's second, third or other IP address. A similar behavior
is dynamic rerouting, which is a secondary function of SCTP's primary path monitoring.
Using NS2 to Monitor Web Traffic over TCP
This scenario examines web traffic over a TCP network. To simulate this case, we defined six nodes:
z node 0 is the client that will request a web page from the web server.
z node 1 is the client's router.
z node 2 is the web cache's primary router.
z node 3 is the web cache's secondary router.
z node 4 is the web cache server.
z node 5 is the web server.
The web cache (node 4) is connected to a web server (node 5) through a router (node 3). The web client (node
0) is connected to web cache (node 4) with connection routed through the client's router (node 1). To simulate
this case scenario, you need the script shown in Listing 2.
Listing 2. TCP Script
When executing ns ./tcpweb.tcl, you will obtain two windows: the network animator and the simulation window.
Figure 5 shows a possible layout of the nodes in simulation window. To get an accurate picture of traffic from
client, bandwidth graphs for the link between nodes 1 and 2 are displayed.
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Figure 5. Dynamic Rerouting of Packets
Link failure occurs between nodes 2 and 4 (Figure 5) as defined by the following lines:
$ns rtmodel-at 3 down $lrmon3 $lmcrt1
$ns rtmodel-at 7 up $lrmon3 $lmcrt1
Packets that were on the link are lost and must be retransmitted. After failure, notice the break in packet traffic
in the bandwidth graphs. TCP packets are now taking another path from web cache to web client. Yet the conn
ection is not lost because of the failure, since we can see that packets are still being exchanged between client
and cache. If the display of nodes is not to your liking, you can change it using the Re-layout function button i
n the simulator window. While playing the simulation, you can change the step using the slider bar. This will be
especially useful during the link failure between three and seven seconds to see dropped packets.
Another interesting aspect of this scenario is the visual server-cache and client-cache interaction. You can see
a model of real-time common interactions on the Internet. Of course, bear in mind that this is a generalized si
mulation.
NS2 Graphical Editor
If you prefer a graphical interface to setup network simulations, NAM supports a drag-and-drop user interface.
You can place network nodes, link them together and define user agents and their associated application or tra
ffic generator. SCTP is not included in this interface because the patch was specific to NS2 source code, not N
AM. NAM is useful for quickly building a network topology. However, we experienced multiple segmentation faul
ts during editing (back up your files often).
The following example explains how to use basic NAM features. The first step is to start an instance of NAM by
executing ./nam. Selecting New in the file menu, you will see the editor window appear. For this example, we a
re trying to build the topology seen in Figure 6.
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Figure 6. NAM Editor
On the toolbar, click on the Add node button and place three nodes in editor window by right clicking at the cor
rect positions. To link nodes, click on Add link. Select one node and drag-click to the next node to create link.
Next, choose which agents you want to use on network in agent drop-down menu. To add an agent, click on t
he appropriate node. Lastly, you choose what applications you want to simulate: either FTP or CBR source. To
add an application, click on the chosen agent. At this point, you can right click on different elements in your to
pology and edit their properties such as color or start and end time for applications. If you get a dialog saying t
hat you must connect your agents, use Add link and connect different agents to simulate your scenario. In cas
e of a blunder, there is a delete button on the toolbar. Note that editor and simulation windows are both part of
NAM, but simulation must first be interpreted by NS2 so that NAM can replay the log of simulation.
Conclusion
We decided to test NS2 because of its support of SCTP (which is a requirement for us), graphical representatio
ns, multiple protocols and many other reasons. However, you need to patch the source code in case the proto
col you want to simulate is not supported and live with low-quality graphics tool.
NS2 is a tool that helps you better understand certain mechanisms in protocol definitions, such as congestion
control, that are difficult to see in live testing. It provides good documentation and support for different add-on
s. We recommend NS2 as a tool to help understand how protocols work and interact with different network top
ologies.
We would like to enforce the need for such tools to be open source and targeted toward supporting Linux. With
the emergence of new protocols, such as IPv6 and SCTP, NS2 can be very useful for the Open Source commu
nity.
Acknowledgements
The Open Systems Lab at Ericsson Research for supporting our work with Linux and open-source software.
Resources
Application and Protocol Testing through Network Emulation
(DARPA) VINT Project
Macroscopic Internet Data Measurement and Analysis
NS2 Home Page
NS2 Tutorial
REAL Network Simulator
Scalable Simulation Framework
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SCTP Patch for NS2
Stream Control Transmission Protocol
University of Essen and Siemens, SCTP Implementation
David Gordon (davidgordonca@hotmail.com) is finishing his Bachelor's degree in Computer Science at Sherbro
oke University in Quebec, Canada. He is currently an intern in the Open Systems Lab at Ericsson Research and
a member of the IPv6 research group. His interests include internet protocols, networking, cryptography and ne
twork security.
Ibrahim F. Haddad (Ibrahim.Haddad@Ericsson.com) is a researcher at the Ericsson Corporate Unit of Research
in Montreal, Canada, where he is involved in researching carrier-class server nodes for real-time all-IP network
s. He is mainly responsible of the security and IPv6 research activities at the Open Systems Lab.
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