Ethernet brings more choice into service equation
Shaw Business Solutions evaluates the benefits of Layer 2 versus Layer 3 services and explains how to decide which Layer 2 service to choose
Few companies have been able to choose between Layer 2 Ethernet and Layer 3 IP/VPN services until very recently. As a result, many communications service providers and enterprises have either chosen to stay with their existing, legacy transport technologies or to opt for Layer 3 services with an expensive managed element. Now Layer 2 Ethernet services are becoming more widely available, they offer customers a ‘middle way’, but only if companies understand which type of service is most appropriate for their needs. Shaw Business Solutions, the Calgary-based wholesale arm of
Canada’s largest cable operator, Shaw Communications, has been delivering Ethernet services since 1997, when it was known as Shaw Fiberlink. Shaw Business Solutions’ Ethernet heritage, which is far longer-standing than most other carriers in this market, means that it is well-placed to advise customers on the suitability of Layer 2 versus Layer 3 services. Lucy Cross, Director, Product Development at Shaw Business
Solutions, suggests that whether or not Layer 2 Ethernet is right for a customer comes down to one important factor: how much control the company wants over its own network. “At Layer 3, the service provider supplying the service takes over the management and control of their customer’s network, including routing control,” Cross points out. “At Layer 2, customers retain that control themselves.”
LAYER 2 ENABLES DESIGN FLEXIBILITY There are several important consequences of an operator or corporate customer maintaining control. If it does, the customer can design its network to work in the way that suits it best. In taking a Layer 3 service, a customer has to accept the way its supplier has architected its network, as well as the way in which the network is operated. If the customer wants to make any changes to a Layer 3 service, for example, adding support for a new protocol, it will need to ask the supplier to implement those changes, incurring cost and delay. With a Layer 2 service, customers gain complete separation between
their network and their provider’s network. They can therefore set their own operational policies, whether these are routing policies or IP addressing schemes, for example. Since the customer is in control, it can make any changes it needs in the network, adding or retiring new equipment, routes and protocols as required. In any case, Layer 2 Ethernet services are protocol-agnostic, supporting a wide range of services, regardless of the underlying transport protocols they use. While
a Layer 3 service only supports IP traffic, Layer 2 Ethernet transparently carries customer traffic governed by IPv4, IPv6, IPX, DECNet, OSI and a host of other protocols. Service cost is a further consideration when weighing up the
benefits of each type of service. Layer 2 services are less costly for a number of reasons. They are at a lower, less complex level of the OSI stack, so the equipment that supports them is simpler and cheaper. There is also evidence that Layer 2 edge devices have lower running costs given their smaller footprint and power consumption. Although Ethernet is a relative newcomer in the carrier domain for many service providers, it has been widely used for years by large corporations across the world and Ethernet equipment suppliers have leveraged these economies of scale to keep their prices low. These factors all have a bearing on the pricing of Layer 2 services. Then there is the fact that Layer 2 services don’t have the managed element inherent in a Layer 3 service. This is also reflected in their lower cost.
ASKING THE RIGHT QUESTIONS However, Cross suggests that a Layer 2 service is not the answer for every customer. Companies will need to have the personnel and technical skill sets to design and operate their own networks, to manage their own routing and to administer their own policies. “Companies will need to consider the monthly recurring costs of a Layer 2 versus a Layer 3 service and the availability and cost of human resources,” she says. “If a carrier or enterprise already has the technical resources and expertise in house, then it will effectively be paying twice for the management element of a Layer 3 service. This is not a one-size-fits-all situation, but for the majority of customers, we find that a Layer 2 service is a better fit with their requirements and organisation.” In summary, Cross advises that companies ask themselves four
questions when trying to determine which type of service is right for them:
- Do I have unique protocol requirements that need to be supported or will all my traffic be IP?
- Do I have the in-house resources and ability to manage a network deployment or do I want a supplier to manage my routing for me?
- Is the product that I am offering over the transport service highly cost-sensitive or can I afford a managed solution?
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