Round Robin Load balancing allows you to distribute client requests across multiple servers. Load balancers improve server fault tolerance and end-user response time. Load balancing distributes client requests across multiple servers to optimize resource utilization. In a scenario with a limited number of servers providing service to a large number of clients, a server can become overloaded and degrade server performance. Load balancing is used to prevent bottlenecks by forwarding the client requests to the servers best suited to handle them. Thus, balancing the load.

In a load balancing setup, the load balancers are logically located between the client and the server farm. Load balancing is used to manage traffic flow to the servers in the server farm. The network diagram shows the topology of a basic load balancing configuration. Load Balancing can be performed on HTTP, HTTP, SSL, FTP, TCP, SSL_TCP, UDP, SSL_BRIDGE, NNTP, DNS, ANY, SIP-UDP, DNS-TCP, and RTSP.

Load balancing uses a number of algorithms, called load balancing methods, to determine how to distribute the load among the servers. When a load balancer is configured to use the round robin method, it rotates incoming requests around to the managed servers, regardless of the load.

The following example shows how a Load Balancer selects a service for load balancing by using the round robin method. The requests are delivered as follows:

• Server-1 receives the first request.
• Server-2 receives the second request.
• Server-3 receives the third request.
  …
  When Server-N receives the N’th request, the round robin routine repeats, and the next request is sent to Server-1, then Server-2, then Server-3, all over again.

Whether it’s load balancing XenApp servers, iPhone/iPad resources, websites, linux servers, windows servers, e-commerce sites, or enterprise applications, NetScaler is the perfect choice. NetScaler, available as a network device or as a virtualized appliance, is a web application delivery appliance that accelerates internal and externally-facing web application up to 5x, optimizes application availability through advanced L4-7 traffic management, increases security with an integrated application firewall, and substantially lowers costs by increasing web server efficiency.

Citrix NetScaler is a comprehensive system deployed in front of web servers that combines high-speed load balancing and content switching with application acceleration, highly-efficient data compression, static and dynamic content caching, SSL acceleration, network optimization, application performance monitoring, and robust application security.

Available as a virtual machine, the NetScaler is perfect for load balancing virtual servers in the datacenter or in the cloud.

Read more here.

Its powerful!

 Kevin Rose the founder of Digg made a prediction in a recent post about how the rumored $99 iTV will change everything. He makes great points about how this could disrupt the Cable TV market and provide a great interactive TV experience for consumers.  This makes me think about whether the iTV could also provide a great platform for business apps as well. Certainly Apple is not targeting businesses with this device, however the same could be said of the iPhone and iPad when they came out. Regardless of the intent, consumers also have day jobs and found ways to put these devices to work.  

At $99 the price is right for a low maintenance Thin Client with a great experience. This could be appealing to many companies including small business or even home offices that may have conceptually considered Thin Clients, but the overhead of learning/implementing/managing a thin client platform was not worth the effort for a small number of devices. For larger companies with security concerns, iOS is fairly locked down already and there is a growing ecosystem of Mobile Device Management solutions that can provide higher levels of control. Including the ability to restrict/prevent time waster apps from being installed. This solution could be ideal for guest offices & cubicles, conference rooms with projectors or HDTV’s, or any task based workstation at many Mac centric organizations. Hotel rooms would be a no-brainer.  

 
What about a mouse? Yes currently this is an issue. Consider this, if the Apple Magic Trackpad will support iTV then gestures and mouse functions can be enabled as it does with Macs. Problem solved ! Even without the Magic Trackpad it is also possible for apps like Receiver to pair an iPhone with an iPad€and serve as a trackpad, so applying this for iTV is not a stretch. There is also ample opportunity for 3rd party keyboard/mouse vendors to provide some great solutions.  

iPhone apps on an iTV ? Even if the hundreds of thousands of iOS apps works with iTV they won’t necessarily look good stretched on a big screen, even the iPhone apps look awkward on the iPad. However if the apps would run as widgets on the “desktop” of a large display this could provide a useful workspace. Apple would need to endorse/allow this but it could be appealing.

Business Apps for the iOS are appearing all the time and many could be appropriate for this scenario, safari web apps and HTML5 apps can work at any size.

Virtual Desktops from an app like Citrix Receiver can provide access to most existing Windows business apps and desktops just as they do today with traditional Thin Clients. Many companies already have the required Infrastructure in place or are considering Desktop Virtualization as an alternative to Windows 7 PC migration/replacements. 

So would the rumored “iTV” really displace the existing niche of Thin Clients ? No. However as we have already seen with iPhones breaking into the enterprise and the iPad successfully defining the Tablet as the 3rd screen most people will have, we could see the iTV legitimize the Thin Client form factor and function plus make it pervasive ( and cool  ).

That would change everything… again..    

I’m often asked what Citrix and the open source community are trying to achieve with the Open vSwitch Project. The Open vSwitch is an open source virtual switch for Xen (and therefore XenServer, and in future perhaps Amazon EC2 and RackSpace), and KVM based virtual infrastructure that replaces the Linux bridge code with a powerful, programmable switch forwarding capability as well as programmable per-virtual interface ACLs. The Open vSwitch supports an emerging industry standard protocol for programming the forwarding plane from an outside controller. This protocol is called OpenFlow. OpenFlow based virtual switches in each server can be logically pooled into a single fabric by an external distributed virtual switch controller to build a dynamic, multi-tenant, programmable datacenter fabric that supports key innovations in cloud computing, as well as allowing us to take advantage of standard x86 CPUs to run a set of rich edge packet-processing functions to secure, direct, filter and otherwise control the delivery of cloud based applications. With the Open vSwitch in place, the Open Stack open source cloud orchestration layer will be able to exert direct control over the data center fabric to deliver a rich, enterprise ready network layer with powerful controls for security, multi-tenancy, load balancing, monitoring, compliance, charge-back and more.

To understand the need for the Open vSwitch, you have to realize that while CPU virtualization, including hardware support, has evolved rapidly over the last decade, network virtualization has lagged behind pretty badly. The dynamism that virtualization enables is the enemy of today’s locked down enterprise networks. For example, migrating a VM between servers could mean that network based firewall and intrusion detection systems are no longer able to protect it. Moreover, many enterprise networks are administered by a different group than the servers, so VM agility challenges an organizational boundary. What we want to achieve is seamless migration of all network-related state for a workload, along with the workload. The obvious place to effect such network changes is in the last-hop switch - which now, courtesy of Moore’s Law and virtualization, is on the server itself, either in the hypervisor or (increasingly) in smart hardware associated with a 10Gb/s NIC card. The Open vSwitch enables granular control over traffic flows, with per flow admission control, the option for rich per packet processing and control over forwarding rules, granular resource guarantees and isolation between tenants or applications, and enables us to dynamically reconfigure the network state for each VM, or for each multi-VM OVF package, as it is deployed or migrated. Network state for each virtual interface becomes a property of the virtual interface, and as a VM moves about the physical infrastructure, all of the policies associated with the VIF move with it. Suddenly the network team is no longer required in order to move a VM between servers.

The Open vSwitch, answers many of the shortcomings of our original hypervisor bridge code, which grew up from the Linux bridge code, and adds powerful features traditionally found only in dedicated switching infrastructure, such as packet filtering, flow admission control and programmable forwarding. It permits us to take advantage of the incredible price/performance benefits of packet processing on standard CPUs, and the near term addition of so-called Single Root I/O Virtualization (SR-IOV) to the edge packet processing feature set will enable the most profound changes in data center and cloud networking architecture since the invention of the router. Most importantly, the Open vSwitch is open source, and will serve multiple hypervisors. I fully expect the community to make it available as a drop-in replacement for the VMware vDS, and to deliver versions of it for a future release of Hyper-V. This then raises the exciting prospect of an entirely open and programmable architecture for networking in the cloud, that is hypervisor independent. As a result, the richness of both private and public cloud networks (and hence their ability to support a greater proportion of enterprise workloads) will not be hypervisor dependent. Open vSwitch offers the ISV ecosystem an enormous opportunity to innovate in edge networking, free of the constraints of traditional network-appliance centric approaches to application delivery, with new, automated management and control plane functions that simplify, accelerate and ease the management of scalable cloud networks.

From a Citrix-specific perspective, Open vSwitch permits us to dynamically instantiate instances of NetScaler VPX, Branch Repeater VPX, or Access Gateway VPX as value-added networking functions withn cloud based networks, and it will enable us to facilitate the seamless extension of the enterprise network to service provider operated clouds. If, as we expect, the Open vSwitch is more broadly endorsed as a common element of future clouds, with open APIs for dynamic control of the data center fabric, it will catalyze an opportunity for all vendors - including those in the network infrastructure business today - to deliver powerful, secure and differentiated cloud architectures.

Many people wonder if the Open vSwitch is “competitive” with the ambitions of traditional networking vendors or with the Cisco Nexus 1000v virtual switch. The answer is “No - indeed the opposite”: The Nexus 1000v from Cisco provides Cisco customers with a powerful distributed switch architecture that brings the value of the full Cisco edge processing capability to virtualized environments, including Cisco management and toolset support. I would have no hesitation in recommending the Cisco product to Cisco customers. It delivers a value-added proposition on top of the basic concept of a dynamically controllable forwarding plane, very similar to OpenFlow and the Open vSwitch.

It would be easy to implement the Nexus 1000v both in parallel with, or on top of, the Open vSwitch. Indeed the value of OpenFlow has been recognized by one Cisco research group, and HP, Dell and NEC are active participants in the development and use of OpenFlow. Startups, such as Netronome and Solarflare are leading the way toward extensive hardware support of the Open vSwitch, permitting native multi-10Gb/s speed switching on server hardware that also hosts virtualized enterprise workloads.

Open vSwitch can be used to replace the VMware vDS, which is a proprietary, rather prosaic implementation of a modestly richer networking stack for vSphere / vCloud. Unfortunately vDS does not separate forwarding and control plane functions clearly, and therefore limits the ability of the ISV ecosystem to innovate on VMware infrastructure. It is tied to the notion of VLANs as network isolation structure, and provides little in the way of differentiated per-application flow treatment. It also has no mapping onto SR-IOV based hardware functions, and therefore has no clear value in a world where increasingly sophisticated second generation SR-IOV NICs are becoming available, with richly programmable forwarding hardware.

The Open vSwitch is a reminder of the incredible power of open source: It catalyzes the contribution of numerous aligned vendors, commoditizes legacy architectures, accelerates the pace of development, and enables a robust ecosystem of value-added providers to exist around a common core feature set. We can look forward to enabling an ecosystem of many value-added networking vendor products around the (commoditized) forwarding function found in all switches and NICs today.

IT has a number of options to enable remote access for employees wanting mobile access to email and work applications from their iPads. There are however pros and cons for each option as well as some prerequisite questions to consider.

Considerations

Company iPads - For company owned iPads a likely scenario is to treat iPads similar to mobile phones. If company apps or email are allowed to run native on the iPad then Mobile Device Management ( MDM ) software may be necessary to assure corporate security policy is enforced. BES servers may be in place already for Blackberry’s, this type of control may be need to be duplicated for company iPads as well. The forth coming improvements in iOS4 will help with email however additional applications will still require management. If however company data is not allowed to reach the iPad as discussed below, then the management costs and administration could be significantly reduced.

Personal iPads - Many early adopter employees and specifically executives are now bringing their new iPad to work and asking IT for access to company apps. One problem is most companies have policies against storing company data on anything but company owned equipment. While the iPad does include a great email app including support for Exchange, the decision needs to be made to change the company policy or allow exceptions for iPad users. Beyond email, corporate calendars are also supported by the iPad, however most users complain of conflicts and errors compared to Outlook Calendar. The best solution for most companies dealing with personal iPads is to not allow apps or data to run locally. IT can provide safe remote access to hosted email and apps or virtual desktops.

Applications - Beyond Email, determining what apps are required by users and if they are available on the iPad is a big consideration. Many company web apps require specific browsers and are not compatible with mobile Safari on the iPad. Windows apps will obviously not work locally and although iWork and a few Office clones are available, most users will find these limiting.

Other Tablets - Since the iPad was announced it seems like there is a new Tablet announced or rumored every week. Some like the Dell Streak or Cisco Cius run Android but others will run Windows or WebOS or MeeGo or other yet to be named OS. The iPad has a head start but it will not be the only Tablet that needs access to company apps. So solving the problem only for iPads will be another point solution for a growing challenge.

Options

Native iPad Apps - If every app required is available on the iPad, then this may be the right answer for company iPads provided they can be managed through MDM software and administration. The pros for native apps are user experience and offline operation ( app dependent ) For personal iPads however assuring corporate security compliance is a challenge with native apps. Also future support for non iPad Tablets should be considered.

VPN with Web Apps - The iPad does have limited native VPN capability in the OS and can support some web apps. These apps need to be tested and expect many not to be compatible. Again consideration for data left behind on personal iPads needs to be taken into account.

Hosted Virtual Applications - Applications running on Windows servers such as Windows XenApp ( or Terminal Services/RDS ) can be an ideal solution for secure iPad app delivery. In addition to Windows apps, Web Apps that require IE or specific browser plug-ins can easily be delivered to iPads. With XenApp IT can dictate what user gets what app and can easily turn on or off access to applications without managing the iPad itself. Only a single app, the Citrix Receiver is required on the iPad and the configuration can be done via email or clicking a link on an intranet web wage. No MDM software is required or concerns about company data on personal iPads. A con of this method is that a WiFi or 3G connection is required and apps will not work offline.
Over 200,000 companies already have Citrix XenApp infrastructure that can support the iPad although some may need configuration changes to enable access. A Citrix Access Gateway is also recommended for secure access, again already in place at many companies. For companies without Citrix, the implementation can be small as a single Windows server with XenApp Fundamentals which is good for between 5 and 75 users.

Virtual Desktops - Hosted Virtual Desktops or Virtual Desktop Infrastructure ( VDI ) such as XenDesktop provides a full Windows 7 environment for each user running on a server in a company datacenter or service provider. Again only the Citrix Receiver is required on the iPad and IT has complete control to turn on or off access. Applications can be installed in the Windows 7 Virtual Machine ( VM ) image or be streamed to the VM image via Application Virtualization. Citrix XenDesktop is required for this solution along with servers supporting the Virtual Desktop images. A free starter edition is available for up to 10 users called XenDesktop Express .

So now that the iPad has topped 3 million units with no slow down in sight, it’s obvious that the tablet form factor has been legitimized and also has a place in business ( or at least remote access to the business ). If you are in IT and considering how to support the iPad let us know your challenges.

I can’t wait for VMworld, next week. It will be fantastic to meet good friends in the virtualization industry, and to feel the freezing fog of San Francisco. And with any luck, I’ll be able to breeze through the halls of the virtualization glitterati undetected, even though my accent bears similarities to that of Mr. Maritz. While on that topic, I sometimes wonder why the Southern African subcontinent has such a striking presence in the world of virtualization: many of the EC2 crew, Paul Maritz, the chaps at Nimbula, and, far behind, me.

I’m also excited about some VMworld sessions. One in particular caught my attention. It’s being run by the VMware minister of misinformation, Eric Horschmann. I’ve crossed swords with him before, and the only thing that’s remarkable is that he’s still hard at it, peddling his view of the future of IT. I call it Horsch-IT. So, if you want to know which will be the hottest session at VMworld, here it is:

PA9449 - Session Title: Winning Against Server Virtualization Competitors: Leading with VMware Strengths, Handling Objections, and Setting Traps

Schedule Information: Tuesday, 2:00 PM (Room: Moscone West Room 3014)
US Speaker: Mark Chuang Group Manager, Product Marketing, VMware, Inc.
Eric Horschman Product Marketing Director, VMware, Inc.

Abstract: (VMware Partners only) Attend this session to learn how to clearly articulate VMware’s advantages in the datacenter and put the competition on the defensive. We’ll demonstrate VMware’s cost advantage against so-called “free” offerings and debunk the most common claims made by competitors. We’ll also show you how to set RFP/POC traps for Microsoft and Citrix that will make it impossible for them to win the deal.

For those (VMware Partners only) that attend this session, I’ll be looking forward to meeting you at XenServer customers, where, it seems (given our download rates, and the number of clouds over 10,000 servers that we’ve built this year) there appears to be no issue understanding that Free = Free always. I love springing my friend Mr Horschmann’s traps. To be perfectly honest, I’m looking forward to seeing him fall into his own trap.