CCNA Wireless – CCNA Wireless Notes Chapter 4

Antenna Characteristics

Different antennas are needed for different applications. An open office space is very different to to a strip of closed offices. How do you cover a large open area such as a lobby? Covering an outdoor area is different than an indoor one and so on.

Radiation Patterns

Antenna gain is normally measured against an isotropic antenna, measured in dBi. This antenna only exists in theory though. It’s shaped like a tiny round point that when alternating current is applied, radiates a signal equally in all directions, in the form of an ever-expanding sphere.

The relative signal strength around an antenna, showed on a plot, is known as the radiation pattern.

The radiation pattern can be shown in a three-dimensional plot in form of a sphere where XY plane lies flat along the horizon and the XZ plane lies vertically along the elevation of the sphere. The first plane is referred to as H plane, horizontal, or also as the azimuth plane. The second one is known as the E plane, elevation.

Polar plots can also be used where concentric circles represent relative changes in signal strength as measured at a constant distance from Continue reading

IDG Contributor Network: Taking a critical look at Workplace by Facebook

Amid the emergence of enterprise social networking (ESN) platforms over the past decade, creating a "Facebook-in-the-enterprise" became a kind of short-hand exhortation by vendors and customer aspirants alike: Could we recreate the success of the world's largest social network within the internal confines of an organization?Now that Workplace by Facebook (formerly Facebook At Work) has more than a year under its belt, we can begin to answer that question. Some customers have indeed found success with the platform, but Real Story Group's evaluation of Workplace finds that what Facebook brings to enterprise social-collaboration is mostly a recognized brand name (you can download the evaluation here). Familiarity can help with initial adoption, but improving employee effectiveness and engagement over the long run may require more than what Workplace—or any other ESN—can offer.To read this article in full or to leave a comment, please click here

IDG Contributor Network: Taking a critical look at Facebook Workplace

Amid the emergence of enterprise social networking (ESN) platforms over the past decade, creating a "Facebook-in-the-enterprise" became a kind of short-hand exhortation by vendors and customer aspirants alike: Could we recreate the success of the world's largest social network within the internal confines of an organization?Now that Facebook Workplace (formerly Facebook At Work) has more than a year under its belt, we can begin to answer that question. Some customers have indeed found success with the platform, but Real Story Group's evaluation of Workplace finds that what Facebook brings to enterprise social-collaboration is mostly a recognized brand name (you can download the evaluation here). Familiarity can help with initial adoption, but improving employee effectiveness and engagement over the long run may require more than what Workplace—or any other ESN—can offer.To read this article in full or to leave a comment, please click here

IDG Contributor Network: How to add JBOC (Just a Bunch of Cloud) to your enterprise

Storage is a fast-evolving industry. Groundbreaking hardware technologies quickly become commoditized, which is a challenge for vendors, but a great benefit to customers. Today’s shiny new array soon becomes matched by a similarly capable JBOD (Just a Bunch of Disk) product that might not have as robust of vendor support, but costs the enterprise far less than a brand-name system. This commoditization extends into flash as well. While it is still growing in adoption in the enterprise, Gartner already sees JBOF (Just a Bunch of Flash) products on the horizon in this segment as well. Cloud storage is on the rise in tandem with flash, and smart data management software can help enterprises overcome the complexity of cloud adoption and easily integrate JBOC (Just a Bunch of Cloud) with their existing architectures. To read this article in full or to leave a comment, please click here

IDG Contributor Network: Why web-scale is the future

While you may associate web-scale networking with cloud giants like Facebook, Google, and Amazon, it’s not just an architecture for the large scale enterprises anymore. The industry has looked at data centers like theirs and asked the question: “What are they doing that we can mimic at a smaller scale?” Through analysis of the way these organizations ran, the term “web-scale” was born, referring specifically to the hyperscale website companies that have built private, efficient, and scalable cloud environments. Since then, it’s become a growing model for organizations to adopt in their journey toward evolving for the future.To read this article in full or to leave a comment, please click here

IDG Contributor Network: Why web-scale is the future

While you may associate web-scale networking with cloud giants like Facebook, Google, and Amazon, it’s not just an architecture for the large scale enterprises anymore. The industry has looked at data centers like theirs and asked the question: “What are they doing that we can mimic at a smaller scale?” Through analysis of the way these organizations ran, the term “web-scale” was born, referring specifically to the hyperscale website companies that have built private, efficient, and scalable cloud environments. Since then, it’s become a growing model for organizations to adopt in their journey toward evolving for the future.To read this article in full or to leave a comment, please click here

IDG Contributor Network: Chaos in the enterprise: Managing IoT services across edge and cloud

Over recent years, the Internet of Things (IoT) has been a huge growth market. From consumer gadgets and wearables to connected cars and smart home devices, the proliferation has been rapid, and IHS predicts that the number of IoT devices globally will reach 30.7 billion by 2020 and 75.4 billion by 2025.IoT is also beginning to touch all aspects of the enterprise. This will only fuel its growth as industry sectors from healthcare to manufacturing become more dependent on IoT communications to drive business processes and missions critical systems.IoT is a key driver of the digital transformation (DX) that is taking place across industry sectors. As the demand for new digital and IoT services continues to grow, close monitoring and management of this transformation will be crucial ensure its success. The rise of IoT has been rapid and will continue to gather pace, to the point where we will soon see entirely new IT infrastructure emerge to support IoT applications and critical systems, spanning the edge, core, and cloud of the service delivery infrastructure.To read this article in full or to leave a comment, please click here

NSX Load Balancing – Accelerated Layer 4 Virtual Servers

In the previous blog, we investigated the basic feature set of NSX Load Balancing, some of the business reasons to use it, and deployed an ESG (Edge Services Gateway), the NSX load balancing platform.  Today, we are going to setup our first virtual server.  When we look at load balancing, it operates at the Transport layer or above of the OSI model and is inclusive of the network layer.  In the most basic of terms, Load Balancing looks at a “session” from the transport layer and applies a load balancing algorithm and a NAT policy to the traffic. I put “session” in quotes because we can load balance both TCP and UDP based applications, but UDP does not have a stateful session, but we can still load balance UDP services.

Whenever someone has stated that and given application cannot be load balanced, I first ask them if the traffic can be processed by a NAT at either the client or server end. If the answer is yes, odds are that it can be load balanced with sufficient understanding of the application and the required ports, protocols and persistence to make the application function correctly. This is Continue reading

Open19: A New Step for Data Centers

While most network engineers do not spend a lot of time thinking about environmentals, like power and cooling, physical space problems are actually one of the major hurdles to building truly large scale data centers. Consider this: a typical 1ru rack mount router weighs in at around 30 pounds, including the power supplies. Centralizing rack power, and removing the sheet metal, can probably reduce this by about 25% (if not more). By extension, centralizing power and removing the sheet metal from an entire data center’s worth of equipment could reduce the weight on the floor by about 10-15%—or rather, allow about 10-15% more equipment to be stacked into the same physical space. Cooling, cabling, and other considerations are similar—even paying for the sheet metal around each box to be formed and shipped adds costs.

What about blade mount systems? Most of these are designed for rather specialized environments, or they are designed for a single vendor’s blades. In the routing space, most of these solutions are actually chassis based systems, which are fraught with problems in large scale data center buildouts. The solution? Some form of open, foundation based standard that can be used by all vendors to build equipment Continue reading

Worth Reading: Transform your career with public speaking

Don’t sit around waiting to be picked. Pick yourself. That simple, low risk step, started a journey. That little step toward fear is how I ended up here, writing this post at a bar on an international flight. Who saw that coming?! Of course, I’m glossing over a many steps in between. After speaking at my job, I worked my way up to speaking at local user groups, then regional conferences. I presented sessions at over a dozen conferences across the US before I worked up the courage to speak overseas. But that first lunch & learn made all the difference. —Free Code Camp

The post Worth Reading: Transform your career with public speaking appeared first on rule 11 reader.

Online meetup recap: Introduction to LinuxKit

At DockerCon 2017 we introduced LinuxKit: A toolkit for building secure, lean and portable Linux subsystems. Here are the key principles and motivations behind the project:

  • Secure defaults without compromising usability
  • Everything is replaceable and customizable
  • Immutable infrastructure applied to building Linux distributions
  • Completely stateless, but persistent storage can be attached
  • Easy tooling, with easy iteration
  • Built with containers, for running containers
  • Designed for building and running clustered applications, including but not limited to container orchestration such as Docker or Kubernetes
  • Designed from the experience of building Docker Editions, but redesigned as a general-purpose toolkit
  • Designed to be managed by external tooling, such as Infrakit or similar tools
  • Includes a set of longer-term collaborative projects in various stages of development to innovate on kernel and userspace changes, particularly around security

For this Online Meetup, Docker Technical Staff member Rolf Neugebauer gave an introduction to LinuxKit, explained the rationale behind its development and gave a demo on how to get started using it.

LinuxKit

Watch the recording and slides

You’ll find below a list of additional questions asked by attendees at the end of the online meetups:

You said the ONBOOT containers are run sequentially, does it wait for one to finish before it Continue reading

US defense contractor stored intelligence data on Amazon server without a password

About 28GB of sensitive US intelligence data was discovered on a publicly-accessible Amazon Web Services’ S3 storage bucket. The cache, containing over 60,000 files, was linked to defense and intelligence contractor Booz Allen Hamilton, which was working on a project for the US National Geospatial-Intelligence Agency (NGA). NGA provides satellite and drone surveillance imagery for the Department of Defense and the US intelligence community.The unsecured data was discovered by Chris Vickery, who now works as a cyber risk analyst for the security firm UpGuard.According to UpGuard, the “information that would ordinarily require a Top Secret-level security clearance from the DoD was accessible to anyone looking in the right place; no hacking was required to gain credentials needed for potentially accessing materials of a high classification level.”To read this article in full or to leave a comment, please click here

US defense contractor stored intelligence data on Amazon server without a password

About 28GB of sensitive US intelligence data was discovered on a publicly-accessible Amazon Web Services’ S3 storage bucket. The cache, containing over 60,000 files, was linked to defense and intelligence contractor Booz Allen Hamilton, which was working on a project for the US National Geospatial-Intelligence Agency (NGA). NGA provides satellite and drone surveillance imagery for the Department of Defense and the US intelligence community.The unsecured data was discovered by Chris Vickery, who now works as a cyber risk analyst for the security firm UpGuard.According to UpGuard, the “information that would ordinarily require a Top Secret-level security clearance from the DoD was accessible to anyone looking in the right place; no hacking was required to gain credentials needed for potentially accessing materials of a high classification level.”To read this article in full or to leave a comment, please click here

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