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Unlocking the Power of Ethernet Solutions in the Enterprise

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IntroductionCreating an economical, reliable, high-speed enterprise network can be challenging when you’re trying to connect a group of geographically dispersed locations. Obstacles that inhibit the realization of this goal include inconsistent presence of fiber and variability in the quality of service. The high systemic overhead and resource requirements for IP-based network technologies also make them unappealing in many computing scenarios. Ethernet solutions, deployed as a wide area networking technology, offer an alternative approach to connecting multiple locations. With high speeds and low overhead, Ethernet can be an attractive proposition for network managers. This paper describes how wide area Ethernet works and the ways it can deliver cost-effective, high-performance connectivity in an extended enterprise network.

A quick note on terminology — wide area Ethernet is also known as “Metro

Ethernet” or “Carrier-Class Ethernet.” While these are both legitimate terms,

the technology itself is often used in settings far more extensive than a

single metro area. Metro Ethernet also sometimes refers to a specific

municipal program to provide Ethernet within city limits. Wide area Ethernet

is much more than that.

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Ethernet as a Wide Area Networking TechnologyMost of us think of Ethernet as a plug in the wall that connects us to a local area network (LAN) and a router that takes us anywhere we want to go on the Internet. Ethernet is that, but it can also be much more than just a local connector. The Ethernet protocol can be used to establish wide area

networks (WANs) or even a national network infrastructure for an organization.

The diagram at the top of Figure 1 shows a simple example of an Ethernet approach to a WAN. In this case, three remote locations and their respective LANs are connected to one another, as well as to the Internet, using a common core Ethernet network, which could be provided by a phone carrier or cable provider. Data that travels from one LAN to another is switched by Ethernet devices that send the data to designated end points on the network according to their respective media access control addresses (MAC addresses).

Though the system might be miles wide, devices on the network see each other as MAC addresses on a local network. It’s like a giant LAN, though the middle passage – the “core Ethernet network” – is a shared infrastructure provided by a third party. The connections between the LANs are virtual private LANs (VLANs), where data moves in encrypted “tunnels.”

A common IP-based alternative, shown in the lower section of Figure 1, is to connect the remote locations using multi-label protocol switching (MPLS). MPLS is a technology used by

Figure 1:

Comparison between a wide area Ethernet virtual LAN (VLAN) solution and a comparable IP-based network connecting three LANs and the Internet.

Though the system might be miles wide, devices on the network see

each other as MAC addresses on a local network. It’s like a giant LAN.

Ethernet can also be much more than just a local connector.

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Figure 2:

The OSI network stack.

From Computer Desktop Encyclopedia © 2004 The Computer Language Co. Inc.

telephone carriers to move data across high-capacity networks. Compared to Ethernet, the MPLS approach is more complex and typically results in a higher level of network overhead. An MPLS network can connect virtually any set of end points without having to be set up specifically to do so. MPLS adds a brief “label” to each packet that acts as shorthand for the IP address where the packet is destined.

The network can then quickly switch the packet across its route without having to reread the IP address in the packet each time. However, the MPLS network’s transformation of packets at the edge is a “level 3-network layer” activity, according to the industry-standard open system interconnection (OSI) stack, shown in Figure 2. Level 3 IP routing is generally slower than Ethernet, which operates at the lower, more-efficient “level 2” or data link layer of the OSI stack. Although it is not always the case, layer 2 switching between physical MAC addresses on an Ethernet is faster and more efficient than the routing of packets based on logical IP addresses.

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Understanding Gaps in IP-Based Wide Area Network InfrastructuresNo IP-based wide area network infrastructure is perfect. There is just too much variability in service availability and quality in any large geographic area. In the context of evaluating the potential of Ethernet, other gaps in traditional network infrastructures include:

• The cost and complexity of adding high-capacity network services in multiple locations can be daunting. Ethernet offers economical, alternative connection circuits, such as COAX, for areas that lack fiber.

• The multistage hand-offs inherent in most IP-based networking solutions add latency to the network traffic when compared to Ethernet.

• The additional hardware and software elements in an IP-based scenario also make the technology more costly and challenging to install and maintain when compared to Ethernet.

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The Business Perspective on Ethernet Network infrastructure is not just a technology issue. Esoteric as it may seem to a business manager, infrastructure is actually mission-critical to a business. In terms of operational expenses, the more complex, multipart infrastructure necessary for traditional IP networks commands a greater share of IT personnel time than Ethernet, which is already supported in almost 100 percent of businesses today. Wide area Ethernet has more uniform equipment requirements and requires fewer specialized resources to manage. Traditional network equipment requirements typically result in a higher capital expenditure than a comparable investment in a wide area Ethernet solution. Depending on who is buying the equipment —the customer or the service provider — that cost may show up as higher costs of network assets or increased service provider costs.

A business will also be affected by uneven bandwidth levels in different locations. Consider, for example, a health care network that wants all of its employees to watch an online training video. If some sites lack fast bandwidth, they will either not be able to see the video, or the act of watching the stream will disrupt other activities such as sending electronic medical records on the network. Today, this kind of rich media access is a serious management imperative. Geographically distributed organizations need this kind of workforce cohesion in order to execute their business strategies. Digital signage (the ability to display video and other data on flat-screen displays throughout multiple locations) is another business requirement that assumes the availability of high bandwidth.

The more complex, multipart infrastructure necessary for traditional IP networks commands a greater share of IT personnel time than Ethernet, which is already supported in almost 100 percent of businesses today.

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Understanding When Ethernet is the Right SolutionSome situations are better suited to Ethernet than others. Ethernet offers the best solution when an enterprise is struggling with some of the gaps in IP-based wide area networks. For example, in a multisite organization, there may be a lack of redundancy and circuit diversity available for the wide area network connections. Circuit diversity is a matter of ensuring that there is more than one network path to a particular location. If there is only one wide area network link and it goes down, the location will be offline until the problem can be fixed. This is obviously not a desirable situation. Adding multiple circuits, however, adds cost and support challenges to the network. A well-designed wide area network Ethernet, especially one running on a major cable backbone, can provide a cost-effective mitigation of the risk of low circuit diversity.

Similarly, Ethernet is a good solution when an organization needs to deliver high-speed connectivity to all locations, regardless of whether or not they are connected through optical fiber. Many locations in the United States lack fiber, and may never get fiber. Ethernet offers a more uniform connection speed across multiple sites. When combined with the potential for greater circuit diversity, an Ethernet solution

results in greater reliability and speed for every connected location. Furthermore, factoring in the generally lower message overhead and latency inherent in Ethernet, the performance benefits are even greater. Remote locations can connect with one another on a reliable, high-speed link with lower latency.

Cost and support challenges should also be considered when contemplating an Ethernet solution. Sometimes, an organization will have perfected its network management with existing network technology. In those cases, Ethernet might be disruptive and not an ideal choice. However, much of the time there is simply not the depth of network management knowledge that’s needed at all remote locations. Servicing the network becomes costly and burdensome. Ethernet is generally simpler to manage than most of its alternatives given its lower hardware requirements and uniform protocol across the entire network. As a result, an Ethernet solution is potentially far more economical.

Ethernet is a good solution when an organization needs to deliver

high-speed connectivity to all locations, regardless of whether

or not they are connected through optical fiber.

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Examples of Wide Area Ethernet SolutionsTo see how Ethernet can benefit a distributed organization, consider the following two examples:

• Logistics hub — Logistics, such as shipping or distribution management, frequently involves connecting locations that are outside of the kind of big-city high-speed networks that corporate offices use. Ethernet can bring a pervasive, high-speed network, which is low in overhead and economical to support, to remote points by connecting to a logistics hub. The business benefits include the ability to run the full depth of computing needed at any location. This is increasingly relevant today as technologies such as supply-chain monitoring and enterprise resource management grow more powerful and computing/network-intensive.

• Data centers and SANs — Ethernet also provides a cost-effective way to manage data center operations. Connections between data centers and business locations, as well as connections to storage area networks (SANs), are a critical component of IT service delivery. Data archiving, transaction integrity and business continuity all depend on reliable, redundant wide area network connections inside the infrastructure regardless of where any one piece is located. Ethernet makes this capability affordable and efficient.

Ethernet can bring a pervasive, high-speed network, which is low in overhead and economical to support, to remote points by connecting to a logistics hub.

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ConclusionEthernet is a potentially powerful tool for organizations seeking to improve their wide area networks in terms of performance, uniformity of service delivery and cost. Some situations are more suitable for Ethernet than others, but organizations that face challenges with variable bandwidth speeds across multiple locations and limited network support resources will find Ethernet appealing from a business perspective.

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