Rolling out business Ethernet

By Fred Ellefson, ADVA Optical Networking -- Ethernet demarcation, service ubiquity, and end-to-end testing, monitoring, and verification of SLAs are key considerations for the cable MSO seeking to offer an intelligent Ethernet service.

Ethernet demarcation, service ubiquity, and end-to-end testing, monitoring, and verification of SLAs are key considerations for the cable MSO seeking to offer an intelligent Ethernet service.

By Fred Ellefson, ADVA Optical Networking

More and more cable multiple-system operators (MSOs) seek to introduce competitive, carrier-class, Ethernet-based business services such as voice-over-Internet Protocol (VoIP), dedicated Internet access, remote site connectivity, and virtual private networks (VPNs). The commercial business opportunity is tremendous, but there are challenges. If an MSO is to provide differentiated Ethernet services to enterprise customers, it must enhance its network with comprehensive operations, administration, and maintenance (OAM) capabilities to keep operational expenses low and customer satisfaction high. Ethernet demarcation, service ubiquity, and end-to-end testing, monitoring, and verification of service-level agreements (SLAs) are key considerations for the MSO seeking to succeed with an intelligent Ethernet service.

An eager but underserved customer base

The enterprise market is ready and waiting for the wide-scale availability of carrier-class Ethernet-based business services. Historically a protocol for linking computers, printers, and other local devices within one building, Ethernet today is seen as the emerging wide area network (WAN) transport foundation—at once powerful and flexible—for enterprise networking.

Enterprises are especially enthusiastic about Ethernet in the WAN for its per-bit cost, about one- sixth that of traditional private-line services based on the calculation that a 1.544-Mbit/sec T1 connection and a 10-Mbit/sec Ethernet link run at about the same price. But Ethernet isn't popular just because it's inexpensive; it's also an old friend to the overwhelmed information technology (IT) department. Ethernet ports account for 90% of the links within enterprise local area networks (LANs). That familiarity is a welcome benefit to the IT staff managing today's enterprise networks, so often in flux to accommodate globalization, mergers, acquisitions, and application innovation.

Nonetheless, few traditional carriers have aggressively rolled out Ethernet offerings over their entire coverage areas, a move they have to make to attract the most lucrative, multisite enterprise customers. Why the reluctance? First, there is the problem of low margins when trying to support bargain-priced Ethernet offerings with legacy telecom infrastructure. And second, many telcos wrestle internally with the possibility of cannibalizing the bird-in-hand revenue streams of traditional Frame Relay, ATM, and private-line offerings in favor of Ethernet-based services.

So into the gap between enterprise interest for Ethernet-based services and telco hesitance to offer such services steps the contemporary MSO.

Of course, these service providers also have obstacles to overcome if they are to cash in on the revenue opportunity. The individual regional operations within a given MSO's network tend to have their own unique infrastructures and processes, and a multisite enterprise customer will want a consistent Ethernet service and SLA across all markets. Plus, there's a bit of skepticism in the enterprise marketplace about contracting with a cable TV provider for mission-critical services. The successful MSO must not allow best-effort Ethernet services to establish first impressions, lest it risk being saddled with the "Cable Guy" stigma and miss the opportunity to replace the traditional carrier as the business-services provider of choice.

Introducing Ethernet demarcation

MSOs determined to stake bold claim in the Ethernet services space would be wise to keep abreast of two key areas of ongoing development: standards work among multiple bodies and the emergence of a new category of intelligent, purpose-built Ethernet demarcation devices based on these standards.

The Metro Ethernet Forum (MEF) is working to standardize Ethernet service definitions, simplifying the delivery of consistent services over the wide variety of access infrastructures that might be in use across an MSO's network. Based on MEF definitions, the MSO can achieve service ubiquity where the Ethernet service looks and behaves the same across all customer locations, regardless of connection media.

Purpose-built demarcation devices—located at the customer premises—help the MSO enforce and verify SLAs based on MEF service definitions. The ability to uphold SLAs with demarcation devices, such as ADVA's patented "Etherjack," could produce the same transformation in the Ethernet marketplace that "smartjack" channel/data service units (CSUs/DSUs) triggered in the Frame Relay arena: mass-market adoption for support of mission-critical applications.

Ethernet demarcation demands two key intelligent components: a user network interface (UNI) and a network interface device (NID). The UNI enables MEF-compliant service definitions through rate limiting and classification, and the NID performs remote OAM, which helps an MSO rapidly isolate and eliminate issues.

With the MEF UNI, an MSO defines the Ethernet service personality. At a high level, this can be broken into service classification and rate limiting for each service. Ethernet service classification is typically done using a combination of virtual LAN (VLAN) IDs, VLAN priorities, type of service (TOS), or digital control signal processor (DCSP) bits. These bits are used to identify the frames that make up individual priorities or services. A bandwidth profile or rate limit is applied to each priority or service, defining a committed or excess information rate (CIR or EIR). The combination of traffic classification and bandwidth profiles is the most visible service attribute for the enterprise.

The NID takes advantage of recent standards from the Institute of Electrical and Electronic Engineers (IEEE) and International Telecommunications Union (ITU) and enables an MSO to perform OAM functions such as loopbacks, test-pattern generation, continuity checks, and cable-integrity tests. These sophisticated capabilities are traditionally associated with carrier private-line services; the MSO, therefore, could encounter some initial skepticism when serving a new enterprise account. That said, performance-management software that enables enterprise customers to monitor hard data on their services can bolster customer confidence.

The NID also enables verification of the four key parameters that the MEF recommends in an SLA: service availability, frame delay, frame jitter, and frames lost. The MSO can measure these parameters end-to-end across the system or separately monitor each of multiple services within a given Ethernet link. This highly granular visibility is of paramount importance to the MSO. Enterprises do not view best-effort or "blind" services as carrier-grade. Consequently, they won't switch to an MSO's Ethernet-based offering from, say, a telco's traditional, tried-and-true Frame Relay service with its embedded performance-monitoring capabilities.


Traditional carriers haven't yet moved decisively and satisfied enterprise demand for Ethernet-based services. For the cable MSO, then, the commercial business opportunity is considerable. However, MSOs must be careful to offer intelligent Ethernet services and avoid being pigeonholed as second-tier providers of "cheap, dumb pipes." Enterprises want the cost point and flexibility of Ethernet but require a consistent, dependable offering that is as carrier-class in every way as their traditional data services. Otherwise, they will not entrust mission-critical business traffic to an MSO. Intelligent Ethernet demarcation helps the MSO deliver on those customer requirements with Ethernet service ubiquity, end-to-end SLA assurance, and carrier-class OAM.

With the enterprise customer eager to shift from traditional data services to more affordable and flexible Ethernet, the opportunity is ripe for MSOs to take the early and sustainable lead in a very promising marketplace.

Fred Ellefsonis vice president of business development at ADVA Optical Networking ( He is an active member of the MEF and speaks around the world on intelligent Ethernet, Ethernet demarcation, and Ethernet OAM issues, among other topics.

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