Answered! Question1 a) What is the purpose of network virtualisation and reducing the number of hops between network devices?…

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Network evolution is long overdue. Server virtualization, mobile computing, the cloud and real-time collaboration have put new demands on the network that legacy designs simply can’t meet. This begs the question: If the current network architecture is outdated, what are the characteristics of an agile network? An agile network needs to be significantly less complex than traditional networks. Additionally, the network being put in place today must be future-proofed to be a foundation for forthcoming initiatives. To meet both of these goals, organizations should look to leverage the power of network virtualization. Virtualization is the act of decoupling an infrastructure service from the physical platform on which that service operates. The IT service that is being utilized is not identified with any physical asset; rather, services exist entirely in a logical abstraction layer running within virtualization software. Network virtualization uses network resources and creates multiple logical network segments that run on a single physical network (Exhibit Three, see page 8). The concept of network virtualization isn’t new. High availability demands have created the need for the dynamic use of alternative resources. The problem with legacy implementations of network virtualization is that one set of network resources—such as links, switches and routers—remains idle while waiting for the failure of an active resource. Although this methodology met the challenge of creating dynamic resources, it was highly inefficient because many network resources remain idle most of the time.

Network virtualization addresses these issues by abstracting control of the resources and centralizing it in a common control plane. This control plane enables the dynamic allocation of the resources based on demand or business policy. Organizations that deploy network virtualization will realize the following benefits.

• Dynamic network control: Network virtualization offers centralized control over all network resources, with the ability to dynamically provision and reconfigure them. Additionally, through the use of northbound APIs, the applications and compute resources can communicate directly with virtual network resources and automate provisioning to optimize application performance and resource utilization.

• Lower cost of hardware: There are many ways network virtualization can reduce the cost of hardware, such as lowering hardware costs and providing more efficient bandwidth utilization. Additionally, because of centralized control and automation, many of the operational processes required to manage the network are also greatly reduced, lowering operational expenses.

• Rapid scalability: Network virtualization creates the ability to rapidly scale the network up or down or to create new networks on demand. This becomes increasingly important as organizations move IT resources to the cloud and shift to an “as-a-service” model.

To achieve network virtualization solutions we must consider the following:

• Simplicity of the solution: The goal of network virtualization is to simplify the network architecture and the operational model. This means the overall solution must simplify many of the complexities associated with legacy networks. For example, the network protocols must be unified at Layers 2 and 3 to avoid overlay complexity. Additionally, the solution must provide topology freedom so all services are available whether the virtual network is operating at Layer 2 or 3.

• Extends beyond the data center: Most network virtualization vendors have solutions targeted at the data center only. Network virtualization can bring tremendous value to points in the network outside the data center including the campus edge, wireless edge and branch offices. Additionally, the solution should span geographically dispersed data centers and make them appear as a single enterprise resource.

• Integrated multi-tenancy: The solution must offer more than just separation of traffic; it must provide full multi-tenant networking. This will allow organizations to keep departmental or tenant networks separated but still offer access to some of the shared services. Additionally, the solution should allow secure zones to be set up across the backbone to isolate different traffic types or groups of users. This is particularly important for businesses operating in environments with regulatory or compliance obligations.

• Improved network uptime: Any solution deployed today must offer sub-second recovery of all network services, including complex ones such as IP multicast. This is in stark contrast to STP, which would often take tens of minutes before all services were made fully available. • Improved scalability: The network must be able to scale beyond the 4,096-VLAN limitation associated with traditional networks. This will provide an excellent foundation for future applications as well as the upcoming wave of mobile devices.

• Open, standards-based solution: There are many ways for solution providers to meet the challenge of network evolution. Many vendors choose to use proprietary protocols and solutions to develop new products. This can sometimes short-cut development time and allow vendors to get products to market early. However, in the long term, it causes vendor lockin and impairs a customer’s ability to choose best-of-breed products in the future. An open, standards-based solution guarantees interoperability with other best-of-breed products and ensures a wide variety of choice. For example, there are a number of candidate replacements for STP; but to date, only Shortest Path Bridging (SPB) is based on a standard (IEEE 802.1aq specifications). TRILL and other protocols have yet to be fully standardized, and this uncertainty may lead to interoperability issues in the future