A primary element of SaaS and cloud computing is the virtual datacenter or Virtual Platform Infrastructure (VPI). VPI refers to virtual machines and virtual platforms that rely on many additional physical and virtual infrastructure elements. Over the past few years, new infrastructure platforms such as virtual machines, virtual management, virtual switching/routing, virtual storage, and virtual system management have come together to help drive cloud computing.

Virtual machine platforms such as VMware ESX and Microsoft Hyper-V are alluring technologies that have the promise of bringing cost savings, infrastructure consolidation, dynamic provisioning and other total cost of ownership benefits to enterprises of all sizes. In addition to providing the tools for building virtual datacenters, there is another critical factor to VPI that cannot be overlooked. The successful implementation of VPI technologies requires a virtual network infrastructure to reliably deliver the virtual datacenter applications.

Virtual WAN Networking
Virtual WAN Networking is the bundling of multiple IP networks from different service providers and or multiple IP connections from a single service provider. The ease and flexibility of network connection provisioning and the automation of the performance and failover of the virtual WAN network are the key to successful virtual WAN networking. Virtual WAN networking is a proven technology that delivers on the same cost-savings, infrastructure consolidation, and dynamic provisioning as virtual machine platforms.

With IP networks taking on many new challenges from VoIP, rich multimedia and other high-bandwidth consuming and high-priority mission-critical applications, as an enterprise customer, business customers require that the network connectivity between them and their SaaS or cloud computing provider is protected with built-in reliability and controls for network performance management.

Cost-Savings
WAN link controllers can deliver easy and affordable WAN and/or ISP network connection aggregation, inbound and outbound WAN load-balancing and failover, and site-to-site channel bonding (see Figure 1). WAN link controllers provide Internet uptime - even if one of the ISPs has an outage. No matter how many ISP connections an organization has, WAN link controllers enable them to leverage low-cost connections, eliminate link congestion and bottlenecks, and manage traffic using QoS and traffic shaping to ensure that only the necessary bandwidth is assigned to specific applications.

WAN link controllers allow network managers to choose the Internet connection performance/cost ratio that best fits business needs, provides complete service provider independence, and eliminates the complexity of network protocols such as border gateway protocol (BGP). Bandwidth aggregation combines Internet connection load balancing to route Internet sessions from congested links to links with more available bandwidth. It also provides automatic failover of Internet sessions from failed links to functioning connections to eliminate a point-of-failure. For example, if a business has a T1 line (1.5 Mbps), and needs additional bandwidth, it would typically have to upgrade to a T3 line (45 Mbps). However, this may be significantly more bandwidth than is required and will result in a significant increase in the overall expense.

With WAN link controllers, this same scenario can be accomplished with two 768 Kbps DSL connections that can be combined for a total aggregated bandwidth equivalent to a T1 - at a fraction of the cost. A customer can also add additional lower speed links such as cable, fiber, and wireless, with a relatively small increase in cost that can more closely match needs. In addition to receiving more cost-effective bandwidth, the WAN link controller dramatically increases WAN network reliability due to the new levels of redundancy through the aggregation of multiple Internet connections.

Network Infrastructure Consolidation
Device consolidation also provides a solution for WAN infrastructure over-provisioning and complexity. By combining the functionality of several stand-alone, single capability devices into one multi-function device, an IT department can address multiple issues related to network complexity, over-provisioning, and cost.

A good example of this is the bringing together of a network firewall, VPN gateway, NAT proxy and SIP proxy within the WAN link controller. Until recently, firewalls and WAN link controllers were separate devices, yet they were increasingly being deployed next to each other. They both provided necessary services to a WAN infrastructure, with the WAN link controller providing Internet connection load balancing and failover for reliability and performance - directing traffic among multiple and diverse WAN and ISP connections; and the firewall providing the network security - protecting the data and applications traveling over the WAN.

Today, WAN link controller vendors are bundling firewall capabilities into their devices. This significantly eases the deployment of both WAN link controller and the firewall, as there is only one system to configure. Moreover, managing and securing WAN traffic is much easier through a single interface. This device combination dramatically reduces equipment, management and ongoing support costs.

Device consolidation continues to expand as technology integration becomes more efficient and solutions become commoditized. VPN gateways, which once enjoyed a rapid popularity within the headquarters, are rapidly becoming bundled within other network devices. While they are useful as stand-alone solutions, the benefits don't always make up for the cost and complexity of their deployment.

Today, the industry is seeing a continued interest in VPN security, but, not necessarily as stand-alone devices. For example, VPN security is bundled within some WAN link controllers. By adding VPN security into a WAN link controller, the cost associated with VPN security is significantly reduced while added value is brought to the WAN link controller.

Dynamic Provisioning
WAN link controllers provide the ability to easily provision multiple, diverse Internet connections and ISPs/telcos (see Figure 2). By having the flexibility to pick and choose service providers at will, and mix and match Internet connections based upon cost, size and type, IT personnel have greater control over their network infrastructure. If one service provider becomes too expensive, or is not performing to expectations, a firm can easily replace them with another service provider. If bandwidth capacity must be increased due to the rollout of a new VoIP application outside of the LAN, simply add another Internet connection to the WAN link controller. An IT department can even enhance the bandwidth management of an application by using QoS and traffic-shaping policies. The WAN link controller will automatically load balance and handle the connection failover.

WAN Link Controllers Deliver Greater Control over Your Network
WAN link controllers allow enterprises to easily automate the process of managing multiple (virtual) IP connections by intelligently transferring over from one connection to another if a network outage occurs, and load balancing traffic between multiple connections based upon each connections performance at any point in time. They provide IT personnel with greater control, and enable them to easily adapt to network changes by providing a resource optimization layer within the WAN network. WAN link controllers do not require ISP or carrier coordination or peering relationships. In fact, they are completely independent from the service provider. This eliminates the peering disputes among service providers that have been known to cause serious connectivity problems for their customers, resulting in loss of productivity and revenue.

A single WAN link controller can be deployed at the enterprise to aggregate multiple disparate connections; or they can be used to "channel bond" multiple connections to create a single virtual connection that combines multiple network connections from multiple service providers. This allows the enterprise to have complete service provider independence and flexibility. This flexibility not only pertains to the choice of service providers, but also gives the enterprise greater options for the type, size and cost of each network connection they choose to deploy. This allows them to take advantage of the most cost-effective ISP rates, while ensuring appropriate levels of bandwidth are available for specific applications. WAN link controllers combine multiple network connections such as T1, T3, DSL, cable, fiber, ISDN, wireless, satellite, and others into a single virtual wide-pipe with aggregated bandwidth, while providing WAN redundancy and automated ISP failover, load balancing, site failover and failback.

Whether using an outside SaaS or cloud provider, a hybrid cloud solution, or you have an internal cloud computing environment, WAN link controllers fit in to provide the virtual network needed to ensure reliable network connectivity and controlled performance.

Disaster Recovery and Business Continuity
Disaster recovery and business continuity help businesses remain up and running in the event of a disaster. Incidents may include local events such as building fires and unplugged network cables, regional events such as earthquakes and hurricanes. From a network technology standpoint, business continuity can be affected by network outage, or a WAN link being congested or bottlenecked, which may limit business functions. WAN link controllers are designed to protect enterprises from all hazardous events. A WAN link controller can also redirect Internet traffic to a disaster recovery site should a catastrophe disrupt a main site. They can help reduce the costs associated with ensuring that site failover and failback occur automatically, making this functionality practical and affordable even for the smallest of enterprises.

WAN link controllers...

• Provide application high-availability over the WAN
• Direct traffic only to "available" WAN links and sites
• Enable administrators to optimize WAN traffic according to throughput capacity
• Enable WAN link redundancy, ISP failover and Internet high-availability among multiple network connections
• Support WAN link aggregation (both inbound and outbound)
• Enable site-to-site channel bonding among multiple locations, providing uninterrupted Internet access for reliable performance of applications such as VPN and VoIP
• Provide redundant hardware failover and monitoring capabilities for mission-critical applications to eliminate potential point of failure
• Provide QoS capabilities for bandwidth management that guarantee your most critical applications get the bandwidth required for smooth and consistent performance
• Easily add and manage multiple service provider connections
• Use any type of IP connectivity (VPNs, private and public links) to support increasing bandwidth needs
• Flexible link deployment and management to help avoid network bottlenecks and service provider outages
• Use multiple ISP and/or WAN links simultaneously, leveraging the total available bandwidth via load-balancing, to maximize connectivity costs, while avoiding unnecessary link costs from underutilized back-up links
• Provide an open solution that avoids hassles such as dealing with BGP and other elements that require service provider cooperation

Summary
In today's competitive and economically challenging business environment, enterprises of all sizes are looking for ways to lower costs, reduce network infrastructure complexity and ease network provisioning. Virtual WAN networking has proven to deliver in each of these areas. Virtualization is a hot topic, and a promising technology area for both datacenter and network provisioning. WAN link controllers are at the front end of virtual WAN networking, and they are the technology devices delivering on the promise of improved total cost of ownership benefits for network infrastructure, while providing the network connectivity to ensure that mission-critical applications are delivered quickly, reliably and securely.