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There's a wide choice of networking methods for linking separate sites within the same business. The number of available options can be bewildering, with services that range from the traditional, such as Leased Lines, through to Ethernet and MPLS IP VPN next-generation wide area networking (WAN) solutions. In this edition, Mark Bennett, THUS' Head of Data Portfolio, looks at the next-generation WAN options and how to go about selecting the most appropriate one for your business.

How they work

Choosing between Ethernet and Multi-Protocol Label Switching (MPLS) IP VPN wide area networking services can be quite straightforward if you have a good idea of your objectives. To help you make your decision, it's worth looking at the two networking technologies, the benefits they can deliver and your communication requirements.

Ethernet is a connectivity service that operates at Layer 2 of the Open Systems Information (OSI) framework. The majority of local area networks (LANs) are based on Ethernet and so your IT staff will be familiar with this protocol. A major benefit of Ethernet WAN services is their ability to seamlessly extend LANs between sites. These services can be connected straight into your LAN switches and so you don't need to purchase a router (unless you wish to route your own IP traffic over the top of the Ethernet service) or even firewalls, as a WAN Ethernet solution is a private networking service.

An MPLS IP VPN service operates at a layer above Ethernet (Layer 3) within the OSI framework. It is a wide area data networking service that offers secure, private IP connectivity to multiple sites, transporting the data according to different levels of priority. The service merges the flexibility, scalability and performance of IP networking with the Quality of Service (QoS) and fast-forwarding abilities associated with ATM. MPLS IP VPN services are 'any to any' in nature.

Ethernet and MPLS IP VPN services offer more bandwidth for a lower cost per Mbps than traditional networking services and each support the transport of a variety of delay-sensitive voice, video and data applications.

How to choose

Both Ethernet and MPLS IP VPN services can be employed to link separate sites within an organisation. However, there are pros and cons associated with each offering and these largely come down to the requirements you have. The key considerations are:

• How many sites need to be connected and at what bandwidth?
• Do you have sufficiently skilled IT resource?
• What applications and services need to run over the network?
• How frequently do you need to perform moves, adds and changes?

Understanding how Ethernet and MPLS IP VPN technologies interact with these factors, and the benefits they provide as result, will help you to make an informed decision.

Bandwidth

THUS National Ethernet services offer circuit bandwidth ranging from 2Mbps to 1Gbps, while our MPLS IP VPN offering supports individual VPN bandwidths from 64Kbps to 300Mbps.

For some businesses, the decision comes down to bandwidth alone. For example, where network bandwidth required between pairs of sites is greater than 300Mbps, then THUS Gigabit Ethernet or even Wavelength services are the most appropriate. Where less than 2Mbps is required, then an MPLS IP VPN service would tend to be more suitable.

In some instances, bandwidth requirements alone could be satisfied by both Ethernet and MPLS IP VPN services. Where this is the case, other business requirements (such as those detailed below) need to be considered.

Number of sites

If you only require networking between two sites, it is likely that an Ethernet service would be less expensive and more suitable than MPLS IP VPN. However, as the number of sites across your network increases it is possible, again, that either service would be suitable.

Skilled IT department

Some organisations would prefer to manage their own IP networking and do not need to involve their telecoms provider because they have sufficiently skilled internal resource. These customers will typically build their own IP VPN networks, based on customer premises equipment (CPE), over the top of connectivity services like THUS National Ethernet.

However, CPE-based IP VPNs can become extremely complex to implement and manage especially where a business has tens of sites. They require that static routes are configured on each CPE router to all other sites which can be quite an overhead. Furthermore, creating a meshed network between lots of sites, using point-to-point connections, can become very expensive compared to an MPLS IP VPN-provisioned network. What's more, if your business is likely to be moving or adding sites to its IP VPN over time, this is far easier to accomplish with THUS MPLS IP VPN. It allows for new sites to be dynamically added to an existing network, without having to reconfigure routers at every site.

Applications and protocols

THUS Ethernet services are currently available in point-to-point or hub-and-spoke configurations. They are ideally suited to applications that are 'client/server' in nature, for example, the ability to provide access to centralised servers and applications. However, where a WAN is required between tens of sites and traffic flows are mainly any to any in nature, for example, driven by the needs of peer-to-peer applications such as VoIP or video conferencing, MPLS IP VPN is generally more cost-effective.

MPLS IP VPN also simplifies network resilience. Due to the flexible, any-to-any nature of IP, it is not necessary to build expensive meshed networks using point-to-point Ethernet circuits to configure static IP routes over these circuits, or configure CE routers to failover between the circuits.

There is a common misconception that Ethernet is better suited to single applications and MPLS IP VPN to multiple ones because of the latter's ability to support different Classes of Service (CoS). The reality is, that once traffic is prioritised onto Ethernet or MPLS IP VPN services, the traffic prioritisation is maintained with both, but differently. With THUS' National Ethernet service, all traffic is treated the same over the network with a single network Quality of Service appropriate to support the majority of voice, video and data applications.

Our MPLS IP VPN service can be purchased with multiple CoS, allowing you to segment your IP VPN bandwidth cost effectively between different types of voice, multimedia and data applications. Each CoS defines how your traffic is prioritised over the MPLS network and the network Quality of Service that is required to ensure effective application performance.

Migration

You may find though that a combination of the two services would be a better option for your business. For example, you may require high bandwidth Ethernet connectivity to distribute content between data centres and an MPLS IP VPN service to connect all your sites together.

Another scenario might involve your current network setup which only needs point-to-point connectivity today but may require any-to-any IP networking over time. In this instance, THUS provides an easy migration path from Ethernet to MPLS.

Before you choose which route to take, use your telecoms provider and their experience to help you make the right decision and ensure that you have considered all the different options, the potential benefits and cost of investment.

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