Welcome!

Cloud Expo Authors: Elizabeth White, Hovhannes Avoyan, Liz McMillan, Yeshim Deniz, Shelly Palmer

Related Topics: Cloud Expo, SOA & WOA, Virtualization, AJAX & REA, Web 2.0

Cloud Expo: Blog Feed Post

The Limits of Cloud: Gratuitous ARP and Failover

Understanding the limitations of cloud will better enable a successful migration strategy

Cloud is great at many things. At other things, not so much. Understanding the limitations of cloud will better enable a successful migration strategy.

One of the truisms of technology is that takes a few years of adoption before folks really start figuring out what it excels at – and conversely what it doesn't. That's generally because early adoption is focused on lab-style experimentation that rarely extends beyond basic needs.

It's when adoption reaches critical mass and folks start trying to use the technology to implement more advanced architectures that the "gotchas" start to be discovered.

Cloud is no exception.

whatclouddoesrightandwrong

 

A few of the things we've learned over the past years of adoption is that cloud is always on, it's simple to manage, and it makes applications and infrastructure services easy to scale.

Some of the things we're learning now is that cloud isn't so great at supporting application mobility, monitoring of deployed services and at providing advanced networking capabilities.

The reason that last part is so important is that a variety of enterprise-class capabilities we've come to rely upon are ultimately enabled by some of the advanced networking techniques cloud simply does not support.

Take gratuitous ARP, for example. Most cloud providers do not allow or support this feature which ultimately means an inability to take advantage of higher-level functions traditionally taken for granted in the enterprise – like failover.

GRATUITOUS ARP and ITS IMPLICATIONS

For those unfamiliar with gratuitous ARP let's get you familiar with it quickly. A gratuitous ARP is an unsolicited ARP request made by a network element (host, switch, device, etc… ) to resolve its own IP address. The source and destination IP address are identical to the source IP address assigned to the network element. The destination MAC is a broadcast address. Gratuitous ARP is used for a variety of reasons. For example, if there is an ARP reply to the request, it means there exists an IP conflict. When a system first boots up, it will often send a gratuitous ARP to indicate it is "up" and available. And finally, it is used as the basis for load balancing failover. To ensure availability of load balancing services, two load balancers will share an IP address (often referred to as a floating IP). Upstream devices recognize the "primary" device by means of a simple ARP entry associating the floating IP with the active device. If the active device fails, the secondary immediately notices (due to heartbeat monitoring between the two) and will send out a gratuitous ARP indicating it is now associated with the IP address and won't the rest of the network please send subsequent traffic to it rather than the failed primary. VRRP and HSRP may also use gratuitous ARP to implement router failover.   how-failure-lb-works

Most cloud environments do not allow broadcast traffic of this nature. After all, it's practically guaranteed that you are sharing a network segment with other tenants, and thus broadcasting traffic could certainly disrupt other tenant's traffic. Additionally, as security minded folks will be eager to remind us, it is fairly well-established that the default for accepting gratuitous ARPs on the network should be "don't do it".

The astute observer will realize the reason for this; there is no security, no ability to verify, no authentication, nothing. A network element configured to accept gratuitous ARPs does so at the risk of being tricked into trusting, explicitly, every gratuitous ARP – even those that may be attempting to fool the network into believing it is a device it is not supposed to be.

That, in essence, is ARP poisoning, and it's one of the security risks associated with the use of gratuitous ARP. Granted, someone needs to be physically on the network to pull this off, but in a cloud environment that's not nearly as difficult as it might be on a locked down corporate network. Gratuitous ARP can further be used to execute denial of service, man in the middle and MAC flooding attacks. None of which have particularly pleasant outcomes, especially in a cloud environment where such attacks would be against shared infrastructure, potentially impacting many tenants.

Thus cloud providers are understandably leery about allowing network elements to willy-nilly announce their own IP addresses.

That said, most enterprise-class network elements have implemented protections against these attacks precisely because of the reliance on gratuitous ARP for various infrastructure services. Most of these protections use a technique that will tentatively accept a gratuitous ARP, but not enter it in its ARP cache unless it has a valid IP-to-MAC mapping, as defined by the device configuration. Validation can take the form of matching against DHCP-assigned addresses or existence in a trusted database.

Obviously these techniques would put an undue burden on a cloud provider's network given that any IP address on a network segment might be assigned to a very large set of MAC addresses.

Simply put, gratuitous ARP is not cloud-friendly, and thus it is you will be hard pressed to find a cloud provider that supports it.

What does that mean?

That means, ultimately, that failover mechanisms in the cloud cannot be based on traditional techniques unless a means to replicate gratuitous ARP functionality without its negative implications can be designed.

Which means, unfortunately, that traditional failover architectures – even using enterprise-class load balancers in cloud environments – cannot really be implemented today. What that means for IT preparing to migrate business critical applications and services to cloud environments is a careful review of their requirements and of the cloud environment's capabilities to determine whether availability and uptime goals can – or cannot – be met using a combination of cloud and traditional load balancing services.

Read the original blog entry...

More Stories By Lori MacVittie

Lori MacVittie is responsible for education and evangelism of application services available across F5’s entire product suite. Her role includes authorship of technical materials and participation in a number of community-based forums and industry standards organizations, among other efforts. MacVittie has extensive programming experience as an application architect, as well as network and systems development and administration expertise. Prior to joining F5, MacVittie was an award-winning Senior Technology Editor at Network Computing Magazine, where she conducted product research and evaluation focused on integration with application and network architectures, and authored articles on a variety of topics aimed at IT professionals. Her most recent area of focus included SOA-related products and architectures. She holds a B.S. in Information and Computing Science from the University of Wisconsin at Green Bay, and an M.S. in Computer Science from Nova Southeastern University.

Cloud Expo Latest Stories
14th International Cloud Expo, held on June 10–12, 2014 at the Javits Center in New York City, featured three content-packed days with a rich array of sessions about the business and technical value of cloud computing, Internet of Things, Big Data, and DevOps led by exceptional speakers from every sector of the IT ecosystem. The Cloud Expo series is the fastest-growing Enterprise IT event in the past 10 years, devoted to every aspect of delivering massively scalable enterprise IT as a service.
As more applications and services move "to the cloud" (public or on-premise) cloud environments are increasingly adopting and building out traditional enterprise features. This in turn is enabling and encouraging cloud adoption from enterprise users. In many ways the definition is blurring as features like continuous operation, geo-distribution or on-demand capacity become the norm. NuoDB is involved in both building enterprise software and using enterprise cloud capabilities. In his session at 15th Cloud Expo, Seth Proctor, CTO at NuoDB, Inc., will discuss the experiences from building, deploying and using enterprise services and suggest some ways to approach moving enterprise applications into a cloud model.
Until recently, many organizations required specialized departments to perform mapping and geospatial analysis, and they used Esri on-premise solutions for that work. In his session at 15th Cloud Expo, Dave Peters, author of the Esri Press book Building a GIS, System Architecture Design Strategies for Managers, will discuss how Esri has successfully included the cloud as a fully integrated SaaS expansion of the ArcGIS mapping platform. Organizations that have incorporated Esri cloud-based applications and content within their business models are reaping huge benefits by directly leveraging cloud-based mapping and analysis capabilities within their existing enterprise investments. The ArcGIS mapping platform includes cloud-based content management and information resources to more widely, efficiently, and affordably deliver real-time actionable information and analysis capabilities to your organization.
In his session at 15th Cloud Expo, Mark Hinkle, Senior Director, Open Source Solutions at Citrix Systems Inc., will provide overview of the open source software that can be used to deploy and manage a cloud computing environment. He will include information on storage, networking(e.g., OpenDaylight) and compute virtualization (Xen, KVM, LXC) and the orchestration(Apache CloudStack, OpenStack) of the three to build their own cloud services. Speaker Bio: Mark Hinkle is the Senior Director, Open Source Solutions, at Citrix Systems Inc. He joined Citrix as a result of their July 2011 acquisition of Cloud.com where he was their Vice President of Community. He is currently responsible for Citrix open source efforts around the open source cloud computing platform, Apache CloudStack and the Xen Hypervisor. Previously he was the VP of Community at Zenoss Inc., a producer of the open source application, server, and network management software, where he grew the Zenoss Core project to over 10...
Almost everyone sees the potential of Internet of Things but how can businesses truly unlock that potential. The key will be in the ability to discover business insight in the midst of an ocean of Big Data generated from billions of embedded devices via Systems of Discover. Businesses will also need to ensure that they can sustain that insight by leveraging the cloud for global reach, scale and elasticity. In his session at Internet of @ThingsExpo, Mac Devine, Distinguished Engineer at IBM, will discuss bringing these three elements together via Systems of Discover.
Cloud and Big Data present unique dilemmas: embracing the benefits of these new technologies while maintaining the security of your organization’s assets. When an outside party owns, controls and manages your infrastructure and computational resources, how can you be assured that sensitive data remains private and secure? How do you best protect data in mixed use cloud and big data infrastructure sets? Can you still satisfy the full range of reporting, compliance and regulatory requirements? In his session at 15th Cloud Expo, Derek Tumulak, Vice President of Product Management at Vormetric, will discuss how to address data security in cloud and Big Data environments so that your organization isn’t next week’s data breach headline.
The cloud is everywhere and growing, and with it SaaS has become an accepted means for software delivery. SaaS is more than just a technology, it is a thriving business model estimated to be worth around $53 billion dollars by 2015, according to IDC. The question is – how do you build and scale a profitable SaaS business model? In his session at 15th Cloud Expo, Jason Cumberland, Vice President, SaaS Solutions at Dimension Data, will give the audience an understanding of common mistakes businesses make when transitioning to SaaS; how to avoid them; and how to build a profitable and scalable SaaS business.
SYS-CON Events announced today that Gridstore™, the leader in software-defined storage (SDS) purpose-built for Windows Servers and Hyper-V, will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Gridstore™ is the leader in software-defined storage purpose built for virtualization that is designed to accelerate applications in virtualized environments. Using its patented Server-Side Virtual Controller™ Technology (SVCT) to eliminate the I/O blender effect and accelerate applications Gridstore delivers vmOptimized™ Storage that self-optimizes to each application or VM across both virtual and physical environments. Leveraging a grid architecture, Gridstore delivers the first end-to-end storage QoS to ensure the most important App or VM performance is never compromised. The storage grid, that uses Gridstore’s performance optimized nodes or capacity optimized nodes, starts with as few a...
SYS-CON Events announced today that Solgenia, the global market leader in Cloud Collaboration and Cloud Infrastructure software solutions, will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Solgenia is the global market leader in Cloud Collaboration and Cloud Infrastructure software solutions. Designed to “Bridge the Gap” between personal and professional social, mobile and cloud user experiences, our solutions help large and medium-sized organizations dramatically improve productivity, reduce collaboration costs, and increase the overall enterprise value by bringing collaboration and infrastructure solutions to the cloud.
Cloud computing started a technology revolution; now DevOps is driving that revolution forward. By enabling new approaches to service delivery, cloud and DevOps together are delivering even greater speed, agility, and efficiency. No wonder leading innovators are adopting DevOps and cloud together! In his session at DevOps Summit, Andi Mann, Vice President of Strategic Solutions at CA Technologies, will explore the synergies in these two approaches, with practical tips, techniques, research data, war stories, case studies, and recommendations.
Enterprises require the performance, agility and on-demand access of the public cloud, and the management, security and compatibility of the private cloud. The solution? In his session at 15th Cloud Expo, Simone Brunozzi, VP and Chief Technologist(global role) for VMware, will explore how to unlock the power of the hybrid cloud and the steps to get there. He'll discuss the challenges that conventional approaches to both public and private cloud computing, and outline the tough decisions that must be made to accelerate the journey to the hybrid cloud. As part of the transition, an Infrastructure-as-a-Service model will enable enterprise IT to build services beyond their data center while owning what gets moved, when to move it, and for how long. IT can then move forward on what matters most to the organization that it supports – availability, agility and efficiency.
Every healthy ecosystem is diverse. This is especially true in cloud ecosystems, where portability and interoperability are more important than old enterprise models of proprietary ownership. In his session at 15th Cloud Expo, Mark Baker, Server Product Manager at Canonical/Ubuntu, will discuss how single vendors used to take the lead in creating and delivering technology, but in a cloud economy, where users want tools of their preference, when and where they need them, it makes no sense.
The 15th International Cloud Expo has just expanded its conference program, to bring together Cloud Computing, APM, APIs, Security, Big Data, Internet of Things, DevOps and WebRTC at one location. Cloud Expo is the single show where delegates and technology vendors can meet to experience and discuss the entire world of the cloud. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to learn about the latest technology developments and solutions.
SYS-CON Events announced today that Bsquare Corporation, a leading enabler of smart connected systems, has been named “Bronze Sponsor” of SYS-CON's Internet of @ThingsExpo, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Bsquare is a global leader of embedded software solutions. We enable smart connected systems at the device level and beyond that millions use every day and provide actionable data solutions for the growing Internet of Things (IoT) market. We empower our world-class customers with our products, services and solutions to achieve innovation and success.
SYS-CON Events announced today that NuoDB, Inc., the leader in webscale distributed database technology, has been named “Bronze Sponsor” of SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. NuoDB was launched in 2010 by industry-renowned database architect Jim Starkey and accomplished software CEO Barry Morris to deliver a webscale distributed database management system that is specifically designed for the cloud and the modern datacenter.