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Chapter 51
Virtual Networking Management and Planning

Trenton Waterhouse

Just as many organizations are reaching a level of comfort with hub and router technology, many vendors are espousing the benefits of switched virtual networks. This chapter examines the issues network planners must evaluate as technology evolves from physical networks built using hubs, bridges, and routers to virtual networks built using switches.

INTRODUCTION

The switch could be considered a third-generation internetworking device. First-generation devices, or bridges, offered a high degree of performance throughput but relatively little value, because the bridge’s limited decision intelligence resulted in broadcast storms that produced network instability. Routers, the second generation of internetworking devices, increased network reliability and offered great value with firewalling capabilities, but the trade off was in performance. When routers are used in combination with each other, bandwidth suffers, which is detrimental for delay-sensitive applications such as multimedia.

The switched virtual network offers all the performance of the bridge with the value of the router. The constraints of physical networking are removed by the logical intelligence that structures and enforces policies of operation to ensure stability and security. Regardless of access technology or geographic location, any-to-any communications is the goal.

THE BUSINESS CASE FOR VIRTUAL NETWORKING

Both the business manager and the technical manager should find interest in this new virtual networking scheme. The business manager is usually interested in cost-of-ownership issues. Numerous studies from organizations such as the Gartner Group and Forrester Research have indicated that only 20% of networking costs are associated with capital equipment acquisition. The other 80% of annual budgets are dedicated to items such as wide area networking charges, personnel, training, maintenance and vendor support, as well as the traditional equipment moves, adds, and changes.

It is important for network planners to remember that capital expenditure happens in year one, even though the equipment may be operating for another four years. WAN charges can account for up to 40% of an organization’s networking budget. For every dollar that the technical staff spends on new equipment, another four dollars is spent on the operation of that equipment. Therefore, focus should be on the cost-of-ownership issues, not necessarily the cost of the network devices.

Network Reliability

Business managers are also looking for increased reliability as the network plays a major role in the core operations of the organization. Networks have become a business tool to gain competitive advantage — they are mission critical and, much like a utility, must provide a highly reliable and available means of communications. Every office today includes an electrical outlet, a phone jack, and a network connection. Electrical and phone service are generally regarded as stable utilities that can be relied on daily. Networks, however, do not always provide such levels of service.

Network Accountability

Managers also can benefit from the increased accountability that virtual networks are able to offer. Organizational networking budgets can range from hundreds of thousands of dollars to hundreds of millions or even billions per year. Accounting for the use of the network that consumes those funds is a critical issue. There is no better example than WAN access charges. Remote site connectivity can consume a great deal of the budget, and the questions of who, what, when, and where in regards to network use are impossible to determine. Most users consider the network to be free, but the tools to manage and account for its use are increasingly a requirement, not an option.

THE TECHNOLOGY CASE FOR VIRTUAL NETWORKING

The technical manager’s needs for higher capacity, greater performance, and increased efficiency can be met through the deployment of switched virtual networks. Each user is offered dedicated bandwidth to the desktop with uplink of increasing bandwidth to servers or other enterprise networks. Rather than contending for bandwidth in shared access environments, all users are provided with their own private link. This degree of privacy allows for increased security because data is sent only to intended recipients, rather than seen by all.

The most attractive feature to the technical manager, however, may be the benefits gained through increased ease of operation and administration of virtual networks. A long-standing objective has been to deliver network services to users without continually having to reconfigure the devices that make up that network, furthermore, many of the costs associated with moves, adds, and changes of users can be alleviated as the constraints of physical networking are removed. Regardless of user location, they can remain part of the same virtual network. Through the use of graphical tools, users are added and deleted from work groups. In the same manner, policies of operation and security filters can be applied. In a sense, the virtual network accomplishes the goal of managing the individual users and individual conversations, rather than the devices that make up the network.

VIRTUAL NETWORKING DEFINED

From the user’s perspective, a virtual network is a data communications system that provides access control and network configuration changes using software control. It functions like a traditional network but is built using switches.

The ideal virtual network does not restrict access to a particular topology or protocol. A virtual network that can only support Ethernet users with TCP/IP applications is limited. The ultimate virtual network allows any-to-any connectivity between Ethernet, Token Ring, FDDI, ATM, IP, IPX, AppleTalk, or SNA networks. A single virtual network infrastructure under a single management architecture is the goal.

Network management software becomes a key enabling requirement for the construction of switched virtual networks. The greatest challenge network designers face is the separation of the physical network connectivity from the logical connection services it can provide. Many of the design issues associated with networks can be attributed to the physical parameters of protocols and the routers used as the interconnection device. A challenge for any network manager is to remain compatible with existing layer 3 protocols and routers and still preserve the investment in existing LAN equipment to the greatest extent possible.


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