White paper

Competencies Required for Wide Area Ethernet

1

IntroductionEthernet now offers a wide area network alternative to traditional IP-based and legacy time-division multiplexing (TDM)-based technologies. Wide area Ethernet can deliver a higher level of performance and uniformity of service levels at a lower cost. To be successful with Ethernet as a wide area solution, however, networking professionals need to sharpen and adapt their Ethernet skills. Designing, building and supporting a wide area Ethernet solution is comparable to the process used with IP-based network technologies. It’s different enough, though, that it deserves its own skills and knowledge focus. This paper presents a high-level discussion of some of the main areas of professional competency that should be cultivated when designing and implementing an Ethernet solution.

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.

2

Ethernet Network TopologiesAn Ethernet is a network of physical devices, as opposed to the traditional logical connections that form an IP network. As a result, the design of a wide area Ethernet requires a solid understanding of physical device addresses (media access control [MAC] addresses), how Ethernet switches work, and how an Ethernet moves packets from one device to another. If you have mostly worked with Ethernet in limited locations, such as a single building, this will represent something of a learning curve.

Basic Ethernet Network ArchitecturesYou have several choices of network architecture for a wide area Ethernet. As Figure 1 shows, there are five basic approaches to Ethernet that you can deploy depending on your business needs and budget. Most wide area Ethernet providers offer these five types of networks. The simplest option, a point-to-point Ethernet, simply connects point A with point B. Point-to-multipoint connects one location to many, while multipoint-to-multipoint connects multiple locations with one another, though without any redundant pathways. In contrast, a mesh approach connects all points with at least two pathways to connect any two points in the network.

Figure 1:

Basic Ethernet network architectures

3

Given that the cost and complexity of implementing and maintaining a wide area Ethernet grows with the number of connections, the architecture you choose will be predicated at least partly on your organization’s need for redundancy and performance. It will also depend on the service options available from your Ethernet provider. It’s not an all-or-nothing choice, however, as most wide area Ethernet plans offer a combination of network

architectures in one solution. You can have a lower-cost point-to-point network architecture in a segment of the network where you can tolerate a possible loss of connectivity but build a mesh where you need higher service delivery levels.

Finding Your Optimal Wide Area Ethernet SolutionThere is no single best design for a wide area Ethernet solution. The optimal setup for your organization will depend on your specific needs. The good news is that most major wide area Ethernet providers can tailor solutions to fit your requirements and even adjust them dynamically over time as your organization evolves.

Flexibility in segmentation is a key concept to grasp when becoming acquainted with what wide area Ethernet can offer your organization. The best wide area Ethernet providers enable you to build your network, one segment at a time, off of a core “converged Ethernet network” of high-speed fiber. From this core, you can architect offshoots that power various

parts of your business. Figure 2 shows a wide area Ethernet solution for an enterprise that consists of corporate offices, logistics facilities and multiple retail locations.

The architecture you choose will be predicated at least partly

on your organization’s need for redundancy and performance.

The best wide area Ethernet providers enable you to build your

network, one segment at a time, off of a core “converged Ethernet

network” of high-speed fiber.

4

SegmentationSegmentation of a wide area Ethernet takes several forms. At the physical level, you want to build circuits that balance the level of performance and reliability you need with the investment you are prepared to make. In the example shown in Figure 2, the corporate offices require the highest level of connection speed, so they have a fiber trunk connecting them to the converged network fiber at the core. The corporate offices are also architected as a partial mesh, providing a high level of redundancy. Why not a full mesh? It would be too costly to justify based on the increase in reliability it provides. This is the kind of calculation regarding circuit diversity that you need to become familiar with as you collaborate with your Ethernet provider to determine your optimal network design.

The warehouses connect to the fiber termination of the core network through Fast Ethernet/Gigabit Ethernet. In the case of the warehouses, each location has its own dedicated point-to-point connection to the core network. The retail locations have a point-to-multipoint architecture that extends, tree-like, from the fiber termination of the core network. The

Figure 2:

Example of a wide area Ethernet solution for a distributed enterprise with multiple network connectivity needs.

5

The whole wide area Ethernet solution itself is a

VLAN because it rides atop a shared-core fiber network

managed by the carrier. However, you can segment this VLAN further

based on your needs.

designer of this network chose a lower level of reliability and performance, but also low cost, for the stores. The business case suggested that downtime for a store was not as critical as downtime at headquarters or the warehouses.

The stores rely on DOCSIS, a mode of Ethernet communication that travels on coaxial cable, typically provided by a cable carrier. DOCSIS is an example of the kind of specific technology that you might need to familiarize yourself with as you prepare to design a wide area Ethernet solution. The combination of DOCSIS and fiber provides you with high level of access to fast connections. In this case, DOCSIS is running at 50 Mbps. In contrast, a T1 line runs at 1.5 Mbps.

The network can also be segmented according to data flow capacity. Again, this is an issue of balancing business need with cost. In the example of Figure 2, the warehouses require a relatively high capacity connection given their need to send and receive very large quantities of inventory data back and forth to headquarters. In contrast, the stores mostly send transaction details from point-of-sale terminals across the network, so their data capacity needs are limited.

Multiple VLANSIt is possible to architect your network as a set of separate or overlapping virtual local area networks (VLANS). The whole wide area Ethernet solution itself is a VLAN because it rides atop a shared-core fiber network managed by the carrier. However, you can segment this VLAN further based on your needs. For example, it is possible to establish a VLAN for priority data. This is done through a process known as packet tagging. The Ethernet standards make it possible for

an Ethernet switcher/router to insert identifying tags into packets as they travel across the network. You can designate tags for packets that have priority over others. For example, you could assign all email traffic a tag of “2,” while transaction data might be a “5,” and so on. The switcher/router will read this part of the packet and understand how to assign transmission priority.

6

Similarly, you could tag packets based on a VLAN assignment. For instance, corporate headquarters might want the highest priority level as well as restricted access. In this case, you would assign a unique VLAN tag to equipment belonging to corporate headquarters. Packets tagged with the corporate VLAN identifier would not be accepted by other switchers/routers in the network. This practice is known as segmenting your network into separate “logical networks.”

Minimizing Collisions and CongestionIf you’ve set up an office LAN, you will be familiar with the issues of collision and congestion on an Ethernet network. Your network is going to be so busy at times that it will be trying to send packets at the very same instant, a process that creates a “collision” between the packets. As with a small LAN, a wide area Ethernet must have a way to resolve these collisions and assure that the packets are resent to their destinations. Your wide area Ethernet provider should be able to help you configure separate collision domains, as well as rules for repeating and restarting packets, to achieve the priority flow of data you require.

Your wide area Ethernet provider should be able to help you configure separate collision domains, as well as rules for repeating and restarting packets, to achieve the priority flow of data you require.

7

Ethernet MEF Certification StandardsThe Metro Ethernet Forum (MEF), a global industry alliance dedicated to the advancement of wide area Ethernet technologies, certifies selected equipment makers, service providers and professionals. The MEF’s goal with certification is to create a reference point of excellence for customers of wide area Ethernet. If you are looking into wide area Ethernet, vendors with MEF certifications should be given strong consideration.

Partnering with the Service ProviderThe good news when you’re planning a wide area Ethernet solution is that you don’t have to do it all by yourself. You can get help and guidance from your Ethernet service provider as well as other professionals who specialize in the technology. However, as with so many IT

endeavors, the working relationship you have with the service provider is a partnership. You will get the best network value for your organization if you have a firm understanding of the core technologies involved.

Making the Business Case for Wide Area EthernetUnderstanding how to make a business case for a new, proposed technology is a fact of life in IT. With wide area Ethernet, being able to articulate potential business advantages is a helpful competency to master. In general, Ethernet tends to be a simpler, lower-cost way of delivering high-speed, reliable network access to a broadly distributed set of locations. This is not always the case, of course, and it is essential that you understand why Ethernet may or may not be the right choice from a financial perspective.

The good news when you’re planning a wide area Ethernet

solution is that you don’t have to do it all by yourself.

8

In simple terms, the business case for wide area Ethernet can be justified based on savings in capital expense (CapX) and operating expense (OpX). CapX refers to the up-front investments required to acquire and install a new technology, while OpX consists of the ongoing costs of running the technology. Traditional IP networks typically require a higher investment in hardware, even if actual per-unit costs are lower. This is because the IP network needs more routers installed by the enterprise. In contrast, the Ethernet solution does not require as many edge devices. 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.

In terms of operational expenses, the more complex, multipart infrastructure necessary for traditional IP networks commands a greater share of IT personnel time and specialized skill sets than Ethernet, which is already supported in almost 100 percent of businesses today.

It is possible to model your own organization’s potential total cost of ownership (TCO) and return on investment for wide area Ethernet compared to alternatives. According to research conducted by Network Strategy Partners, a firm that advises clients on networking, the adoption of wide area Ethernet can result in a TCO that is 63 percent lower than MPLS.1 The Network Strategy Partners paper models numerous details of OpX and CapX, including data center costs and service contracts. Your specific situation will likely be different, but the research indicates that there is a strong case for a financial benefit to wide area Ethernet.

Going beyond hard dollars, it is useful to examine some intangible business factors associated with the network. For example, a business can be affected by uneven bandwidth levels in different locations. For example, it is increasingly common today for organizations to include rich media repositories as part of their intranets. Digital online video is a common tool in knowledge capture, training and compliance. Consider the proliferation of video-based training on workplace codes of conduct and so forth. Similarly, modern CEOs enjoy having the ability to stream live “town hall” webcasts to remote locations and make everyone feel included in the company’s affairs. All of this requires reliable, high-capacity bandwidth.

1 Network Strategy Partners. Total Cost of Ownership Comparison: Ethernet Transport vs. VPLS and MPLS in the Metro Network, 2008.

9

ConclusionWide area Ethernet is a big topic, one that vastly outstrips the ability of a brief paper such as this to explain in full. However, our hope is that by providing you with some basic recommended competencies, you will be better able to assess the viability and desirability of an Ethernet solution for your organization. If you are in the process of designing and implementing an Ethernet solution, this paper should give you some competencies to consider. To summarize, our main recommendation is that network professionals become familiar (or more familiar) with the nuances of a device-to-device (MAC address)-based network over a wide area. In addition, we want to emphasize the importance of matching Ethernet solution specifications to business requirements and avoid “one-size-fits-all” thinking. Ethernet offers many options for flexible network design and optimization of data flow, bandwidth and traffic priority. Finally, your Ethernet provider should be a rich information resource for you in the entire process. We are available to help you figure out the best wide area networking solution for your enterprise.

ii

To find out more about Time Warner Cable Business Class, visit www.twcbc.com/tx or call XXX-XXX-XXXX.

Follow and talk with us on social media. In addition to the information and resources at the

Time Warner Cable Business Class website, you can also find us on Facebook and LinkedIn.