Groups seek solutions as the MAN becomes the 'problem child'



Some of the optical network's most formidable problems still lie in bridging the telecommunications gap between lucrative enterprise business traffic and the MAN transport system. First, there's the infamous bottleneck created by attempting to converge multiple types of traffic onto a single optical transport network. Other problems lie in compatibility (or lack thereof), scalability, resiliency, robustness, and economics-not to mention the exploding demand for more bandwidth still driven hard by a fast-growing data market.

In fact, getting manufacturers, carriers, and customers to simply agree on critical issues surrounding the metro market is a huge obstacle. In the midst of this push for consistency, several organizations are forming to meet these challenges head-on by formally banding industry players together to further a particular goal-all in the name of simplifying metro architectures and resolving issues that may be delaying the evolution of optical networking in our cities.

Two such groups emerged in force at SuperComm 2001 in June, taking advantage of this huge gathering of the telecom industry to hold meetings and recruit new members. The Resilient Packet Ring Alliance (RPRA), founded in January, and the Metro Ethernet Forum (MEF), formally introduced at SuperComm, are both beating the drum of simplifying the MAN, but each marches to a slightly different drumbeat.

The RPRA is committed to promoting a standard for resilient packet ring (RPR) technology for the networking industry and educating vendors and carriers on the benefits of an IEEE standard. To make RPR successful, RPRA is assisting the IEEE 802.17 RPR Working Group to develop that standard.

"Specifically, [the RPRA objective] is to facilitate industry convergence to ward RPR as the technology of choice for data-optimized, carrier-class metro networks," says Robert Love, president of LAN Connect Consultants (Raleigh, NC) and RPRA chairman. "RPR is being developed because a large group of carriers and vendors believe that the most effective method of carrying traffic for many carriers' MANs will be RPR."

Love believes the changes from current standard offerings, such as SONET and Ethernet, to deliver the capabilities available with RPR are substantial. Meanwhile, efforts required to develop this new standard could produce significant benefits for users, including scalability, interoperability, and a single cost-effective technology that addresses the requirements of both the voice and data traffic destined for the MAN.

"These benefits will be worth the additional time required to create the IEEE 802.17 resilient packet ring standard," says Love. "I see RPR as an enabling technology for carrying end-to-end Ethernet and SONET services over the MAN and for carrying voice traffic with carrier-class network resiliency."

RPRA expects significant portions of the proposed standard to be drafted by the start of its November meeting, even as final presentations are being made on alternative approaches for RPR implementation.

Meanwhile, the focus on accelerating the adoption of optical Ethernet solutions in the MAN is the charter of the Metro Ethernet Forum. MEF plans to drive the acceptance of existing and new technologies and standards that enable end-to-end service creation over Ethernet, while optimizing operation, administration, and management of Ethernet in the MAN.

"We plan to address issues such as resiliency, SLAs [service-level agreements], QoS [quality of service] and support for voice traffic in optical Ethernet networks," says Nan Chen, director of product marketing for Atrica (Santa Clara, CA) and MEF president. "The forum has embraced a network service business model, while organizations like the RPRA and the 10-Gigabit Ethernet Alliance are dedicated to promoting a specific technology standard [IEEE 802.17 for RPRA and IEEE 802.3ae for 10-Gigabit Ethernet Alliance]. The MEF intends to work with and complement these organizations' efforts."

According to Chen, service providers building large-scale, heterogeneous networks, both national and/or international, will deploy complementary networking technologies. As service providers expand their infrastructures, a combination of economics and operational and logistical attributes will mandate viability and adoption of various service technologies. MEF's work and that of other strategic alliances will enable service providers to select or combine technologies as they build metro networks.

While the objectives of RPRA and MEF may differ in part when considering the metro as a whole, there is overlap where Ethernet is considered. The obvious difference is that while MEF is pushing for existing Ethernet standards in creating today's MAN, the RPRA is pushing just as hard for a brand new standard, resilient packet ring, for transporting Ethernet-based traffic. MEF's focus will include multiple transport technologies. The question is whether the overlap will result in competing or complementary goals.

"Both organizations will benefit if we view the overlap as an opportunity to work cooperatively," says Love. "Other areas that do not overlap will provide each group with the chance to make unique, independent contributions to this dynamic industry. Based on my meetings with Nan Chen, it was apparent to both of us that we share significant common interests and goals."

Not only do they have common interests and goals, but both organizations also share common members. For example, Dynarc Inc. (San Jose, CA), a MAN solution provider that promotes Ethernet as the dominant technology in LANs and soon MANs, holds dual membership in both groups.

"Any standards body with a technology applicable in the metro must make sure the standard is adapted for Ethernet," says Fredrik Hanell, vice president of marketing for Dynarc. "Ethernet is thus forcibly one significant input parameter in the RPRA's work in marketing and contributing to the IEEE 802.17 workgroup. MEF intends to work with a focus, pushing for efficient Ethernet transport over available and emerging standardized protocols such as RPR, end-to-end over the MAN."

Companies like Dynarc view RPRA and MEF as complimentary, benefiting by participating in both horizontal efforts pushing for efficiency of end-to-end transport of services as well as vertical efforts pushing for improving individual technological elements used along the path.

"It's all about maintaining the system's perspective while excelling in technological expertise," says Hanell. "Al though for natural reasons there are differences in opinion ranging from a fundamentalist 'there can be only one' attitude to a more moderate 'one amongst others' attitude, the common goal for the participants is to make networking more efficient."

RPRA ( boasts about 60 member companies and MEF ( has about 40 members.

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