The document discusses datacenter network design and transport protocols. It begins with an introduction to traditional datacenter network topologies, which use a 2-3 level tree structure. It then covers fat-tree and DCell topologies as alternatives. The document also discusses how TCP, while commonly used, is not optimal for datacenter networks due to design assumptions like round-trip time that differ from wide-area networks. It suggests transport protocols designed for datacenter characteristics could improve performance.
Intel- Next Generation Datacenters & Clouditnewsafrica
Intel- Next Generation Datacenters & Cloud. Presented at the September 05, 2013 edition of the IT News Africa Innovation Dinner (www.innovationdinner.co.za)
Intel- Next Generation Datacenters & Clouditnewsafrica
Intel- Next Generation Datacenters & Cloud. Presented at the September 05, 2013 edition of the IT News Africa Innovation Dinner (www.innovationdinner.co.za)
Re-architecting the Datacenter to Deliver Better Experiences (Intel)COMPUTEX TAIPEI
COMPUTEX TAIPEI 2013 - Cloud Industry Forum
Topic: Re-architecting the Datacenter to Deliver Better Experiences
Speaker:Lisa H. Graff
Vice President and General Manager of Datacenter Marketing Group, Intel
Cisco at VMworld 2015 - Cisco UCS as the Foundation for Software-Defined Data...ldangelo0772
IT is in the midst of a dramatic shift to the mobile-cloud era, one in which IT services can be consumed on-demand across the enterprise and in hybrid and public clouds. Tjerk Bijlsma will share the latest Cisco Unified Computing System (Cisco UCS) innovations that can help you shape your Software-Defined Data Center, radically simplifying IT while delivering services at the speed of today's business.
During this session you will learn about:
Cisco's comprehensive architectural approach to enable next wave of IT convergence that includes VMware vSAN and comprehensive vRealize integration as part of the SDDC.
Innovations in Cisco Data Center portfolio including Cisco UCS and Nexus integrations with VMware solutions.
Solutions for virtualized environments for Converged and Hyper Converged systems including FlexPod, VersaStack, Vblock, vSAN, Simplivity, StorMagic and more.
Datacenter event - green it amsterdam - maikel bouricius - 15-09-14Karim Network
On September 15th, Green IT Amsterdam and Paris Region Entreprises invited you to join them in Paris and get some insight into European knowledge and expertise on datacenters, especially on the sustainability issues.
WE learned more about the PEDCA project and How to reorganize computer rooms and data centers in an energy efficient way !
An efficient datacenter design can save companies money and ensure systems availability. The first step in reducing energy consumption and emissions is to understand the environment. A high performance data center is not only good for the business, but an environmentally and socially responsible way to manage operations. Find out more from this presentation given by CEO of DP Air Corp, Arnie W. Evdokimo.
TECHNOLOGY ACCELERATING INFRASTRUCTURE DEVELOPMENT FOR ATTAINING THE NIGERIAN...itnewsafrica
Presented at the September 17, 2013 edition of the IT News Africa Innovation Dinner, by Umar Buba Bindir (PhD), CEO/Director General, National Office for Technological Acquisition and Promotion.
Network Repairs provides high skilled professional service on network support in Mississauga Brampton; our team finds network issues quickly to resolve. Our technicians give this high priority as this is directly linked with business for security of data and information.
Apache Jackrabbit Oak is a new JCR implementation with a completely new architecture. Based on concepts like eventual consistency and multi-version concurrency control, and borrowing ideas from distributed version control systems and cloud-scale databases, the Oak architecture is a major leap ahead for Jackrabbit. This presentation describes the Oak architecture and shows what it means for the scalability and performance of modern content applications. Changes to existing Jackrabbit functionality are described and the migration process is explained.
Database migration from Sybase ASE to PostgreSQL @2013.pgconf.eualdaschwede80
The talk explains some differences between Sybase ASE and PostgreSQL and shows two different migration strategies - the dump reload process and replication.
Re-architecting the Datacenter to Deliver Better Experiences (Intel)COMPUTEX TAIPEI
COMPUTEX TAIPEI 2013 - Cloud Industry Forum
Topic: Re-architecting the Datacenter to Deliver Better Experiences
Speaker:Lisa H. Graff
Vice President and General Manager of Datacenter Marketing Group, Intel
Cisco at VMworld 2015 - Cisco UCS as the Foundation for Software-Defined Data...ldangelo0772
IT is in the midst of a dramatic shift to the mobile-cloud era, one in which IT services can be consumed on-demand across the enterprise and in hybrid and public clouds. Tjerk Bijlsma will share the latest Cisco Unified Computing System (Cisco UCS) innovations that can help you shape your Software-Defined Data Center, radically simplifying IT while delivering services at the speed of today's business.
During this session you will learn about:
Cisco's comprehensive architectural approach to enable next wave of IT convergence that includes VMware vSAN and comprehensive vRealize integration as part of the SDDC.
Innovations in Cisco Data Center portfolio including Cisco UCS and Nexus integrations with VMware solutions.
Solutions for virtualized environments for Converged and Hyper Converged systems including FlexPod, VersaStack, Vblock, vSAN, Simplivity, StorMagic and more.
Datacenter event - green it amsterdam - maikel bouricius - 15-09-14Karim Network
On September 15th, Green IT Amsterdam and Paris Region Entreprises invited you to join them in Paris and get some insight into European knowledge and expertise on datacenters, especially on the sustainability issues.
WE learned more about the PEDCA project and How to reorganize computer rooms and data centers in an energy efficient way !
An efficient datacenter design can save companies money and ensure systems availability. The first step in reducing energy consumption and emissions is to understand the environment. A high performance data center is not only good for the business, but an environmentally and socially responsible way to manage operations. Find out more from this presentation given by CEO of DP Air Corp, Arnie W. Evdokimo.
TECHNOLOGY ACCELERATING INFRASTRUCTURE DEVELOPMENT FOR ATTAINING THE NIGERIAN...itnewsafrica
Presented at the September 17, 2013 edition of the IT News Africa Innovation Dinner, by Umar Buba Bindir (PhD), CEO/Director General, National Office for Technological Acquisition and Promotion.
Network Repairs provides high skilled professional service on network support in Mississauga Brampton; our team finds network issues quickly to resolve. Our technicians give this high priority as this is directly linked with business for security of data and information.
Apache Jackrabbit Oak is a new JCR implementation with a completely new architecture. Based on concepts like eventual consistency and multi-version concurrency control, and borrowing ideas from distributed version control systems and cloud-scale databases, the Oak architecture is a major leap ahead for Jackrabbit. This presentation describes the Oak architecture and shows what it means for the scalability and performance of modern content applications. Changes to existing Jackrabbit functionality are described and the migration process is explained.
Database migration from Sybase ASE to PostgreSQL @2013.pgconf.eualdaschwede80
The talk explains some differences between Sybase ASE and PostgreSQL and shows two different migration strategies - the dump reload process and replication.
A presentation to help new network operators plan a project to improve their network traffic management. Useful for inbound and outbound heavy networks. Lists the things you need to do to reach routing and peering nirvana.
The video is available on YouTube: https://www.youtube.com/watch?v=dEot3Fb1iB4
Have you heard of a Node100 problem? Naïve Erlang clusters are complete network graphs which tend to blow up with a only a handful (100+) number of nodes. Solution is partially-connected mesh networks. The tricky part is easy communication for devs and transparent cluster management for devops.
In Spil Games n-tier architecture we use native Erlang message passing between tiers. Thus our cluster size (way over 500) requires partially connected network.
In this talk I will present a library which helps to create and maintain medium to large Erlang clusters. We have been using it for over 2 years now and time has come to announce and open-source it.
This talk is a part of the continuous effort Spil Games is making to give back to the community, as seen in Erlang Factory 2014 with the release of erl-cache and erl-memcache.
Target audience
Engineers interested or working with medium to large-scale Erlang clusters.
IMS to DB2 Migration: How a Fortune 500 Company Made the Move in Record Time ...Precisely
Hear first-hand from Damon Anderson, Manager of Data Services at a leading Fortune 500 global distribution company, about how he researched and solved his IMS-to-DB2 migration challenge.
IMS applications continue to run many of today’s leading financial, manufacturing, and government agencies’ most critical business processes. However, we all know the developers that wrote and supported those applications are fast leaving the work force, creating a major skills gap, unwanted risk, and a pressing need for an efficient DB2 migration path.
While some organizations are having to turn to expensive 3rd party vendors to support these applications, the potential data security breaches and challenges in ensuring consistent quality of application support and maintenance make that a risky, expensive proposition.
Hear how Damon and his team mitigated these challenges by migrating their IMS application databases to DB2 with Syncsort DL/2 and how it helped them:
o avoid a skills gap
o eliminate their MLC costs for IMS DB and the significant costs for 3rd party IMS Support tools
o create a platform for future modernization of their core business applications
Leveraging Endpoint Flexibility in Data-Intensive ClustersRan Ziv
Part of the Apache Spark and Mesos projects.
Based on an article of Mosharaf Chowdhury, Srikanth Kandula and Ion Stoica from University of California, Berkeley.
The article was presented in SIGCOMM 2013 in Hong Kong.
Efficient Data Center Virtualization with QLogic 10GbE Solutions from HPJone Smith
QLogic 10GbE network solutions from HP delivers significant operational savings, high performance, reduced management complexity and improved scalability for virtualized data center deployments.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
SAP Sapphire 2024 - ASUG301 building better apps with SAP Fiori.pdfPeter Spielvogel
Building better applications for business users with SAP Fiori.
• What is SAP Fiori and why it matters to you
• How a better user experience drives measurable business benefits
• How to get started with SAP Fiori today
• How SAP Fiori elements accelerates application development
• How SAP Build Code includes SAP Fiori tools and other generative artificial intelligence capabilities
• How SAP Fiori paves the way for using AI in SAP apps
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
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.
Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdfPaige Cruz
Monitoring and observability aren’t 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 company’s observability stack.
While the dev and ops silo continues to crumble….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:
Welocme to ViralQR, your best QR code generator.ViralQR
Welcome to ViralQR, your best QR code generator available on the market!
At ViralQR, we design static and dynamic QR codes. Our mission is to make business operations easier and customer engagement more powerful through the use of QR technology. Be it a small-scale business or a huge enterprise, our easy-to-use platform provides multiple choices that can be tailored according to your company's branding and marketing strategies.
Our Vision
We are here to make the process of creating QR codes easy and smooth, thus enhancing customer interaction and making business more fluid. We very strongly believe in the ability of QR codes to change the world for businesses in their interaction with customers and are set on making that technology accessible and usable far and wide.
Our Achievements
Ever since its inception, we have successfully served many clients by offering QR codes in their marketing, service delivery, and collection of feedback across various industries. Our platform has been recognized for its ease of use and amazing features, which helped a business to make QR codes.
Our Services
At ViralQR, here is a comprehensive suite of services that caters to your very needs:
Static QR Codes: Create free static QR codes. These QR codes are able to store significant information such as URLs, vCards, plain text, emails and SMS, Wi-Fi credentials, and Bitcoin addresses.
Dynamic QR codes: These also have all the advanced features but are subscription-based. They can directly link to PDF files, images, micro-landing pages, social accounts, review forms, business pages, and applications. In addition, they can be branded with CTAs, frames, patterns, colors, and logos to enhance your branding.
Pricing and Packages
Additionally, there is a 14-day free offer to ViralQR, which is an exceptional opportunity for new users to take a feel of this platform. One can easily subscribe from there and experience the full dynamic of using QR codes. The subscription plans are not only meant for business; they are priced very flexibly so that literally every business could afford to benefit from our service.
Why choose us?
ViralQR will provide services for marketing, advertising, catering, retail, and the like. The QR codes can be posted on fliers, packaging, merchandise, and banners, as well as to substitute for cash and cards in a restaurant or coffee shop. With QR codes integrated into your business, improve customer engagement and streamline operations.
Comprehensive Analytics
Subscribers of ViralQR receive detailed analytics and tracking tools in light of having a view of the core values of QR code performance. Our analytics dashboard shows aggregate views and unique views, as well as detailed information about each impression, including time, device, browser, and estimated location by city and country.
So, thank you for choosing ViralQR; we have an offer of nothing but the best in terms of QR code services to meet business diversity!
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
Elevating Tactical DDD Patterns Through Object CalisthenicsDorra BARTAGUIZ
After immersing yourself in the blue book and its red counterpart, attending DDD-focused conferences, and applying tactical patterns, you're left with a crucial question: How do I ensure my design is effective? Tactical patterns within Domain-Driven Design (DDD) serve as guiding principles for creating clear and manageable domain models. However, achieving success with these patterns requires additional guidance. Interestingly, we've observed that a set of constraints initially designed for training purposes remarkably aligns with effective pattern implementation, offering a more ‘mechanical’ approach. Let's explore together how Object Calisthenics can elevate the design of your tactical DDD patterns, offering concrete help for those venturing into DDD for the first time!
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
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.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
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.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
State of ICS and IoT Cyber Threat Landscape Report 2024 preview
Topic 15: Datacenter Design and Networking
1. 15: Datacenter Design and Networking
Zubair Nabi
zubair.nabi@itu.edu.pk
April 21, 2013
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 1 / 27
2. Outline
1 Datacenter Topologies
2 Transport Protocols
3 Network Sharing
4 Wrapping Up
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 2 / 27
3. Outline
1 Datacenter Topologies
2 Transport Protocols
3 Network Sharing
4 Wrapping Up
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 3 / 27
5. Introduction
Datacenters are traditionally designed in the form of a 2/3-level tree
Switching elements become more specialized and faster when we go
up the tree structure
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 4 / 27
6. Introduction
Datacenters are traditionally designed in the form of a 2/3-level tree
Switching elements become more specialized and faster when we go
up the tree structure
A three-level tree has a core switch at the root, aggregation switches
in the middle, and edge switches at the leaves of the tree
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 4 / 27
7. Introduction
Datacenters are traditionally designed in the form of a 2/3-level tree
Switching elements become more specialized and faster when we go
up the tree structure
A three-level tree has a core switch at the root, aggregation switches
in the middle, and edge switches at the leaves of the tree
Edge switches have a large number of 1Gbps ports and a small
number of 10Gbps ports
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 4 / 27
8. Introduction
Datacenters are traditionally designed in the form of a 2/3-level tree
Switching elements become more specialized and faster when we go
up the tree structure
A three-level tree has a core switch at the root, aggregation switches
in the middle, and edge switches at the leaves of the tree
Edge switches have a large number of 1Gbps ports and a small
number of 10Gbps ports
The 1Gbps ports connect end-hosts while 10Gbps ports connect to
aggregation switches
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 4 / 27
9. Introduction
Datacenters are traditionally designed in the form of a 2/3-level tree
Switching elements become more specialized and faster when we go
up the tree structure
A three-level tree has a core switch at the root, aggregation switches
in the middle, and edge switches at the leaves of the tree
Edge switches have a large number of 1Gbps ports and a small
number of 10Gbps ports
The 1Gbps ports connect end-hosts while 10Gbps ports connect to
aggregation switches
Aggregation and core switches have 10Gbps ports
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 4 / 27
10. Introduction
Datacenters are traditionally designed in the form of a 2/3-level tree
Switching elements become more specialized and faster when we go
up the tree structure
A three-level tree has a core switch at the root, aggregation switches
in the middle, and edge switches at the leaves of the tree
Edge switches have a large number of 1Gbps ports and a small
number of 10Gbps ports
The 1Gbps ports connect end-hosts while 10Gbps ports connect to
aggregation switches
Aggregation and core switches have 10Gbps ports
Partitioning if switches up the tree go down
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 4 / 27
11. Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 5 / 27
12. Oversubscription
Ideal value of 1:1 – All hosts may potentially communicate with others
at full bandwidth of their interface
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 6 / 27
13. Oversubscription
Ideal value of 1:1 – All hosts may potentially communicate with others
at full bandwidth of their interface
5:1 – Only 20% of the bandwidth is available (200Mbps)
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 6 / 27
14. Oversubscription
Ideal value of 1:1 – All hosts may potentially communicate with others
at full bandwidth of their interface
5:1 – Only 20% of the bandwidth is available (200Mbps)
Typical datacenter designs are oversubscribed by a factor of 2.5:1
(400Mbps) to 8:1 (125Mbps)
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 6 / 27
16. Fat-tree Topology
k-ary fat-tree has k pods
Each pod contains two layers of k/2 switches
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 7 / 27
17. Fat-tree Topology
k-ary fat-tree has k pods
Each pod contains two layers of k/2 switches
Each k-port switch in the lower layer is directly connected to k/2 hosts
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 7 / 27
18. Fat-tree Topology
k-ary fat-tree has k pods
Each pod contains two layers of k/2 switches
Each k-port switch in the lower layer is directly connected to k/2 hosts
Each of the remaining k/2 ports is connected to k/2 of the k ports of the
aggregation switches
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 7 / 27
19. Fat-tree Topology
k-ary fat-tree has k pods
Each pod contains two layers of k/2 switches
Each k-port switch in the lower layer is directly connected to k/2 hosts
Each of the remaining k/2 ports is connected to k/2 of the k ports of the
aggregation switches
(k/2)2
core switches
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 7 / 27
20. Fat-tree Topology
k-ary fat-tree has k pods
Each pod contains two layers of k/2 switches
Each k-port switch in the lower layer is directly connected to k/2 hosts
Each of the remaining k/2 ports is connected to k/2 of the k ports of the
aggregation switches
(k/2)2
core switches
Each core switch has one port connected to each of the k pods
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 7 / 27
21. Fat-tree Topology
k-ary fat-tree has k pods
Each pod contains two layers of k/2 switches
Each k-port switch in the lower layer is directly connected to k/2 hosts
Each of the remaining k/2 ports is connected to k/2 of the k ports of the
aggregation switches
(k/2)2
core switches
Each core switch has one port connected to each of the k pods
The ith port of any core switch is connected to pod i
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 7 / 27
22. Fat-tree Topology
k-ary fat-tree has k pods
Each pod contains two layers of k/2 switches
Each k-port switch in the lower layer is directly connected to k/2 hosts
Each of the remaining k/2 ports is connected to k/2 of the k ports of the
aggregation switches
(k/2)2
core switches
Each core switch has one port connected to each of the k pods
The ith port of any core switch is connected to pod i
A k-ary fat-tree supports k3
/4 hosts
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 7 / 27
23. Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 8 / 27
24. DCell
Uses a recursively defined structure to interconnect servers
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 9 / 27
25. DCell
Uses a recursively defined structure to interconnect servers
Each server connects to different levels of DCells through multiple links
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 9 / 27
26. DCell
Uses a recursively defined structure to interconnect servers
Each server connects to different levels of DCells through multiple links
High-level DCells are built recursively from many low-level ones
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 9 / 27
27. DCell
Uses a recursively defined structure to interconnect servers
Each server connects to different levels of DCells through multiple links
High-level DCells are built recursively from many low-level ones
Fault tolerant as there is no single point of failure
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 9 / 27
28. Structure
Uses servers with multiple network ports and mini-switches to
construct its recursive structure
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 10 / 27
29. Structure
Uses servers with multiple network ports and mini-switches to
construct its recursive structure
DCell0 is the building block to construct larger DCells
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 10 / 27
30. Structure
Uses servers with multiple network ports and mini-switches to
construct its recursive structure
DCell0 is the building block to construct larger DCells
Consists of n servers and a mini-switch
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 10 / 27
31. Structure
Uses servers with multiple network ports and mini-switches to
construct its recursive structure
DCell0 is the building block to construct larger DCells
Consists of n servers and a mini-switch
High-level DCells are built recursively from many low-level ones
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 10 / 27
32. Structure
Uses servers with multiple network ports and mini-switches to
construct its recursive structure
DCell0 is the building block to construct larger DCells
Consists of n servers and a mini-switch
High-level DCells are built recursively from many low-level ones
DCell1 constructed using n +1 DCell0s
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 10 / 27
33. Structure
Uses servers with multiple network ports and mini-switches to
construct its recursive structure
DCell0 is the building block to construct larger DCells
Consists of n servers and a mini-switch
High-level DCells are built recursively from many low-level ones
DCell1 constructed using n +1 DCell0s
The same applies to DCellk
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 10 / 27
34. Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 11 / 27
35. Outline
1 Datacenter Topologies
2 Transport Protocols
3 Network Sharing
4 Wrapping Up
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 12 / 27
36. TCP and UDP
TCP: Connection-oriented with reliability, ordering, and congestion
control
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 13 / 27
37. TCP and UDP
TCP: Connection-oriented with reliability, ordering, and congestion
control
UDP: Connectionless with no ordering, reliability, or congestion control
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 13 / 27
38. TCP and Datacenter Networks
Communication between different nodes is thought of as just opening a
TCP connection between them
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 14 / 27
39. TCP and Datacenter Networks
Communication between different nodes is thought of as just opening a
TCP connection between them
Common sockets API
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 14 / 27
40. TCP and Datacenter Networks
Communication between different nodes is thought of as just opening a
TCP connection between them
Common sockets API
But TCP was designed for a wide-area network
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 14 / 27
41. TCP and Datacenter Networks
Communication between different nodes is thought of as just opening a
TCP connection between them
Common sockets API
But TCP was designed for a wide-area network
Clearly, a datacenter is not a wide-area network
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 14 / 27
42. TCP and Datacenter Networks
Communication between different nodes is thought of as just opening a
TCP connection between them
Common sockets API
But TCP was designed for a wide-area network
Clearly, a datacenter is not a wide-area network
Significantly different bandwidth-delay product, round-trip time (RTT),
and retransmission timeout (RTO)
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 14 / 27
43. TCP and Datacenter Networks
Communication between different nodes is thought of as just opening a
TCP connection between them
Common sockets API
But TCP was designed for a wide-area network
Clearly, a datacenter is not a wide-area network
Significantly different bandwidth-delay product, round-trip time (RTT),
and retransmission timeout (RTO)
For example, due to the low RTT, the congestion window for each flow
is very small
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 14 / 27
44. TCP and Datacenter Networks
Communication between different nodes is thought of as just opening a
TCP connection between them
Common sockets API
But TCP was designed for a wide-area network
Clearly, a datacenter is not a wide-area network
Significantly different bandwidth-delay product, round-trip time (RTT),
and retransmission timeout (RTO)
For example, due to the low RTT, the congestion window for each flow
is very small
As a result, flow recovery through TCP fast retransmit is impossible,
leading to poor net throughput
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 14 / 27
45. More problems for TCP
In production data centers, due to the widely-varying mix of
applications, congestion in the network can last from 10s to 100s of
seconds
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 15 / 27
46. More problems for TCP
In production data centers, due to the widely-varying mix of
applications, congestion in the network can last from 10s to 100s of
seconds
In commodity switches the buffer pool is shared by all interfaces
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 15 / 27
47. More problems for TCP
In production data centers, due to the widely-varying mix of
applications, congestion in the network can last from 10s to 100s of
seconds
In commodity switches the buffer pool is shared by all interfaces
If long flows hog the memory, queues can build up for the short flows
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 15 / 27
48. More problems for TCP
In production data centers, due to the widely-varying mix of
applications, congestion in the network can last from 10s to 100s of
seconds
In commodity switches the buffer pool is shared by all interfaces
If long flows hog the memory, queues can build up for the short flows
Many-to-one communication patterns can lead to TCP throughput
collapse or incast
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 15 / 27
49. More problems for TCP
In production data centers, due to the widely-varying mix of
applications, congestion in the network can last from 10s to 100s of
seconds
In commodity switches the buffer pool is shared by all interfaces
If long flows hog the memory, queues can build up for the short flows
Many-to-one communication patterns can lead to TCP throughput
collapse or incast
This can cause overall application throughput to decrease by up to 90%
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 15 / 27
50. More problems for TCP
In production data centers, due to the widely-varying mix of
applications, congestion in the network can last from 10s to 100s of
seconds
In commodity switches the buffer pool is shared by all interfaces
If long flows hog the memory, queues can build up for the short flows
Many-to-one communication patterns can lead to TCP throughput
collapse or incast
This can cause overall application throughput to decrease by up to 90%
In virtualized environments, the time sharing of resources increases
the latency faced by the VMs
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 15 / 27
51. More problems for TCP
In production data centers, due to the widely-varying mix of
applications, congestion in the network can last from 10s to 100s of
seconds
In commodity switches the buffer pool is shared by all interfaces
If long flows hog the memory, queues can build up for the short flows
Many-to-one communication patterns can lead to TCP throughput
collapse or incast
This can cause overall application throughput to decrease by up to 90%
In virtualized environments, the time sharing of resources increases
the latency faced by the VMs
This latency can be orders of magnitude higher than the RTT between
hosts inside a datacenter, leading to slow progress of TCP connections
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 15 / 27
53. Reaction
Some large-scale deployments have abandoned TCP altogether
For instance, Facebook now uses a custom UDP transport
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 16 / 27
54. Reaction
Some large-scale deployments have abandoned TCP altogether
For instance, Facebook now uses a custom UDP transport
It might be a “kitchen-sink” solution but it is sub-optimal in a datacenter
environment
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 16 / 27
55. Reaction
Some large-scale deployments have abandoned TCP altogether
For instance, Facebook now uses a custom UDP transport
It might be a “kitchen-sink” solution but it is sub-optimal in a datacenter
environment
Over the years, a number of alternatives have been proposed
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 16 / 27
56. Datacenter TCP (DCTCP)
Uses Explicit Congestion Notifications (ECN) from switches to perform
active queue management-based congestion control
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 17 / 27
57. Datacenter TCP (DCTCP)
Uses Explicit Congestion Notifications (ECN) from switches to perform
active queue management-based congestion control
Switches set the congestion experienced flag in packets whenever the
buffer occupancy exceeds a small threshold
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 17 / 27
58. Datacenter TCP (DCTCP)
Uses Explicit Congestion Notifications (ECN) from switches to perform
active queue management-based congestion control
Switches set the congestion experienced flag in packets whenever the
buffer occupancy exceeds a small threshold
DCTCP uses this information to reduce the size of the window based
on a fraction of the marked packets
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 17 / 27
59. Datacenter TCP (DCTCP)
Uses Explicit Congestion Notifications (ECN) from switches to perform
active queue management-based congestion control
Switches set the congestion experienced flag in packets whenever the
buffer occupancy exceeds a small threshold
DCTCP uses this information to reduce the size of the window based
on a fraction of the marked packets
Enables it to react quickly to queue build and avoid buffer pressure
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 17 / 27
60. Multipath TCP (MPTCP)
Establishes multiple subflows over different paths between a pair of
end-hosts
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 18 / 27
61. Multipath TCP (MPTCP)
Establishes multiple subflows over different paths between a pair of
end-hosts
These subflows operate under a single TCP connection
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 18 / 27
62. Multipath TCP (MPTCP)
Establishes multiple subflows over different paths between a pair of
end-hosts
These subflows operate under a single TCP connection
The fraction of the total congestion window for each flow is determined
by its speed
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 18 / 27
63. Multipath TCP (MPTCP)
Establishes multiple subflows over different paths between a pair of
end-hosts
These subflows operate under a single TCP connection
The fraction of the total congestion window for each flow is determined
by its speed
Moves traffic away from the most congested paths
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 18 / 27
64. tcpcrypt
Backwards compatible enhancement to TCP that aims to efficiently
and transparently provide encrypted communication to applications
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 19 / 27
65. tcpcrypt
Backwards compatible enhancement to TCP that aims to efficiently
and transparently provide encrypted communication to applications
Uses a custom key exchange protocol that leverages the TCP options
field
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 19 / 27
66. tcpcrypt
Backwards compatible enhancement to TCP that aims to efficiently
and transparently provide encrypted communication to applications
Uses a custom key exchange protocol that leverages the TCP options
field
Like SSL, to reduce the cost of connection setup for short-lived flows, it
enables cryptographic state from one TCP connection to bootstrap
subsequent ones
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 19 / 27
67. tcpcrypt
Backwards compatible enhancement to TCP that aims to efficiently
and transparently provide encrypted communication to applications
Uses a custom key exchange protocol that leverages the TCP options
field
Like SSL, to reduce the cost of connection setup for short-lived flows, it
enables cryptographic state from one TCP connection to bootstrap
subsequent ones
Applications can also be made aware of the presence of tcpcrypt to
negate redundant encryption
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 19 / 27
68. Deadline-Driven Delivery (D3
)
Targets applications with distributed workflow and latency targets
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 20 / 27
69. Deadline-Driven Delivery (D3
)
Targets applications with distributed workflow and latency targets
Such applications associate a deadline with each network flow and the
flow is only useful if the deadline is met
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 20 / 27
70. Deadline-Driven Delivery (D3
)
Targets applications with distributed workflow and latency targets
Such applications associate a deadline with each network flow and the
flow is only useful if the deadline is met
Applications expose flow deadline and size information which is
exploited by end hosts to request rates from routers along the data path
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 20 / 27
71. Outline
1 Datacenter Topologies
2 Transport Protocols
3 Network Sharing
4 Wrapping Up
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 21 / 27
72. Introduction
Network resources are shared amongst the tenants, which can lead to
contention and other undesired behaviour
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 22 / 27
73. Introduction
Network resources are shared amongst the tenants, which can lead to
contention and other undesired behaviour
Network performance isolation between tenants can be an important
tool for:
Minimizing disruption from legitimate tenants that run network-intensive
workloads
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 22 / 27
74. Introduction
Network resources are shared amongst the tenants, which can lead to
contention and other undesired behaviour
Network performance isolation between tenants can be an important
tool for:
Minimizing disruption from legitimate tenants that run network-intensive
workloads
Protecting against malicious tenants that launch DoS attacks
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 22 / 27
75. Introduction
Network resources are shared amongst the tenants, which can lead to
contention and other undesired behaviour
Network performance isolation between tenants can be an important
tool for:
Minimizing disruption from legitimate tenants that run network-intensive
workloads
Protecting against malicious tenants that launch DoS attacks
The standard methodology to ensure isolation is to use VLANs
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 22 / 27
76. Virtual LAN
Acts like an ordinary LAN but end-hosts do no necessarily have to be
physically connected to the same segment
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 23 / 27
77. Virtual LAN
Acts like an ordinary LAN but end-hosts do no necessarily have to be
physically connected to the same segment
Nodes are grouped together by the VLAN
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 23 / 27
78. Virtual LAN
Acts like an ordinary LAN but end-hosts do no necessarily have to be
physically connected to the same segment
Nodes are grouped together by the VLAN
Broadcasts can also be sent within the same VLAN
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 23 / 27
79. Virtual LAN
Acts like an ordinary LAN but end-hosts do no necessarily have to be
physically connected to the same segment
Nodes are grouped together by the VLAN
Broadcasts can also be sent within the same VLAN
VLAN membership information is inserted into Ethernet frames
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 23 / 27
80. Rate-limiting End-hosts
In Xen the network bandwidth available to each domU can be rate
limited
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 24 / 27
81. Rate-limiting End-hosts
In Xen the network bandwidth available to each domU can be rate
limited
Can be used to implement basic QoS
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 24 / 27
82. Rate-limiting End-hosts
In Xen the network bandwidth available to each domU can be rate
limited
Can be used to implement basic QoS
The virtual interface is simply rate-limited
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 24 / 27
83. Outline
1 Datacenter Topologies
2 Transport Protocols
3 Network Sharing
4 Wrapping Up
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 25 / 27
84. The End
In reverse order:
1 Cloud stacks be used to turn clusters and datacenters into private and
public clouds
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 26 / 27
85. The End
In reverse order:
1 Cloud stacks be used to turn clusters and datacenters into private and
public clouds
2 Virtualization of computation, storage, and networking can allow many
tenants to co-exist
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 26 / 27
86. The End
In reverse order:
1 Cloud stacks be used to turn clusters and datacenters into private and
public clouds
2 Virtualization of computation, storage, and networking can allow many
tenants to co-exist
3 Most data does not fit the relational model and is more suited for
NoSQL stores
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 26 / 27
87. The End
In reverse order:
1 Cloud stacks be used to turn clusters and datacenters into private and
public clouds
2 Virtualization of computation, storage, and networking can allow many
tenants to co-exist
3 Most data does not fit the relational model and is more suited for
NoSQL stores
4 Data-intensive, task-parallel frameworks abstract away the details of
distribution, work allocation, sychronization, concurreny, and
communication; Perfect match for the cloud
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 26 / 27
88. The End
In reverse order:
1 Cloud stacks be used to turn clusters and datacenters into private and
public clouds
2 Virtualization of computation, storage, and networking can allow many
tenants to co-exist
3 Most data does not fit the relational model and is more suited for
NoSQL stores
4 Data-intensive, task-parallel frameworks abstract away the details of
distribution, work allocation, sychronization, concurreny, and
communication; Perfect match for the cloud
5 The future is Big Data and Cloud Computing!
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 26 / 27
89. References
1 Mohammad Al-Fares, Alexander Loukissas, and Amin Vahdat. 2008. A
scalable, commodity data center network architecture. In Proceedings
of the ACM SIGCOMM 2008 conference on Data communication
(SIGCOMM ’08). ACM, New York, NY, USA, 63-74.
2 Chuanxiong Guo, Haitao Wu, Kun Tan, Lei Shi, Yongguang Zhang, and
Songwu Lu. 2008. Dcell: a scalable and fault-tolerant network
structure for data centers. In Proceedings of the ACM SIGCOMM 2008
conference on Data communication (SIGCOMM ’08). ACM, New York,
NY, USA, 75-86.
Zubair Nabi 15: Datacenter Design and Networking April 21, 2013 27 / 27