The drive to standardise.

Over the past decade, enterprise networking, once typified by diversity, has standardised and converged. Rather than choosing from a range of network topologies, the vast majority of businesses today run local area networks (LANs) based on Ethernet architecture, with alternatives such as Token Ring now used only rarely. Vendor Cisco Systems estimates that 85% of network connections to PCs and workstations run over Ethernet.

This convergence is also being driven by the uptake of IP (Internet Protocol) standards. Although these standards were developed to enable wide area connections over the public internet, IP increasingly extends to the desktop either through protocols such as TCP/IP, or through applications such as voice over IP (VoIP) or instant messaging.

Increasingly, today's enterprise networks use the same core technologies as carriers and service providers at the high end, and as consumers in entry-level markets - simplifying the complicated landscape of devices.

The main differences are in capacity and resilience. The essential building blocks -- Ethernet and IP -- are essentially the same.

One development that has driven this standardisation is the take-up of Ethernet over fibre networks. Service providers are using Ethernet, rather than frame relay and ATM, to connect to enterprise customers.

ATM suffers from complexity, while frame relay has a maximum practical speed of around 50Mbps. Ethernet operates effectively from 1Mbps to 10Gbps, is simpler to set up and gives service providers, and their customers, more flexibility over how the network is configured.

Developments such as running Ethernet services over carriers' SONET (synchcronous optical network) or SDH (synchronous digital hierarchy) networks has led to growth in Metro Ethernet networks. This has further entrenched Ethernet as the networking technology of choice for businesses, and has expanded the range of services available on IP-based networks.

This, along with a clear roadmap for increases to 10 gigabit speeds, has prompted the networking and communications industry to move away from propriety networking technologies and offer a wider range of new services over Ethernet LANs and WANs.

Video conferencing, security surveillance, and connections for sensor equipment in production and distribution, are just some of the services that are now available on Ethernet and increasingly, using IP-based networks. All this makes it far easier to build seamless WANs for a variety of tasks.

But perhaps the most significant extension to an organisation's networking capabilities is support for voice telephony. VoIP is on the verge of becoming a mainstream technology, especially among larger businesses. Industry analysts Meta Group estimates that 50% of large enterprises will have production-scale VoIP systems by 2008.

Some of the uptake for VoIP is undoubtedly being driven by the need to replace older analogue or digital phone systems. These can be expensive to extend and maintain, and require engineers to maintain know-how in proprietary technology.

VoIP resolves some of these problems, but demand is also being driven by the availability of converged services, such as video calling, and presence-based services.

These technologies enable companies to build "right-time" communications systems, that route calls, emails, or instant messages to staff based on their availability. Staff do not have to be in the same building, as long as they are on an IP-based network.

The networking industry has developed the session-initiation protocol (SIP) to manage applications that use presence awareness. SIP can be used for voice, data and video based communications. SIP, though, does not require changes to the underlying network topology. Rather, SIP is likely to reinforce the dominant position of Ethernet and IP as networking standards.

According to Forrester Research, early adopters of SIP-based applications will be in medicine, the emergency services and finance, all fields where quick decision making is vital. But applications such as unified conferencing rely not just on SIP, but on a converged network in order to operate.

Hence an infrastructure based on Ethernet and IP, and using SIP, is the emerging de facto standard - although many organisations need to proceed step by step, investing in new equipment that preserves some of their existing investments. For example, multiprotocol label switching devices and IP PBXs can support existing standards.

Most enterprises are moving towards simpler, converged networks. A study by Meta Group found that 80% of companies polled planned to run voice, video and data over a single network.

But achieving this will require investment. Meta estimates that 51% of large enterprises (over 1500 employees) have a complete switched IP LAN to the desktop. The remainder will need to update their networking hardware if they are to run a fully converged network, and take full advantage of VoIP or SIP-based applications.

Businesses also need to address the issue of resilience. One barrier to the uptake of VoIP is the need to ensure that IP-based networks are robust enough to carry voice traffic. Although they can be expensive to maintain, existing dedicated voice and video circuits are usually reliable. Simply upgrading switches on an Ethernet network may not ensure reliable multi-mode IP services: businesses need to carry out a thorough survey to find bottlenecks and points of failure.

Network managers also need to allow for the fact that the boundaries of the enterprise are probably less clearly defined than they have ever been. Not only do enterprises have to communicate with suppliers and customers, but they also need to communicate with employees who might work from home, or mostly on the move.

A modern network architecture needs the capability to deliver data to any device, not just the desktop PC or terminal. This trend is most marked in the VoIP area, where networking equipment vendors such as 3Com and Cisco Systems have entered the telephone handset market.

But businesses will also want to extend access to voice, video and data to users of handheld computers, connecting either locally over a wireless LAN, through a public Wifi hotspot or through GPRS and UMTS cellular networks. Businesses will certainly want to run soft phones and messaging applications on handheld devices as much as on their desktop systems.

Extending the company network to include wireless devices is made easier by the choice of IP-based services, and the basic compatibility between the Wifi standard and Ethernet. Although building a robust and secure wireless network requires careful planning, support for standards makes this easier than it might have been.

A converged infrastructure for voice, video and data will most likely be based around a copper or fibre Ethernet, with network services delivered over IP both on the LAN and the WAN. Steps to standardisation:

LANs on Ethernet

Uptake of IP standards

VoIP breaking into mainstream

Development of SIP simpler converged voice, data and video network