T&M TRENDS: The NextGen Challenge

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Synchronous data transmission over fiber optic networks is achieved by Synchronous Optical Network (SONET) and synchronous digital hierarchy (SDH). SONET is the U.S. version of the standard published by American National Standard Institute (ANSI). SDH is the international version of the standard published by International Telecommunications union (ITU).

The First-generation SONET/SDH equipment was add/ drop multiplexer (ADM), which was based on the original set of standards. Next-generation test equipment was SONET/SDH switch, with the mechanism of mapping Ethernet on SONET. The third-generation test equipment uses tools like virtual concatenation (VCAT), generic framing procedure (GFP), and Link capacity adjustment scheme (LCAS). Next generation SONET/SDH devices are supporting Resilient Packet Ring (RPR) for scalability, bandwidth efficiency, class of service support features.

SONET/SDH is preferred more than plesiochronous digital hierarchy (PDH) because of its compatibility with standard equipment from different vendors. When sophisticated services with high bandwidth are required, SONET/SDH finds its importance. SONET/SDH capitalizes the voice transport ability with high vendor interoperability.

Bench-top SONET/SDH test equipment are generally used in the research and development and manufacturing applications, where as the portable/hand-held test equipment are used for installation and maintenance applications. SONET/SDH operates at different line rates including OC 3, OC 12, OC 48, and OC 768.

Technology

GFP: GFP is a standard to tag traffic adaptation features. It provides convergence between packet switched network and the transmission network. It uses VCAT to provide right-sized pipes for data services. GFP has two modes namely

Frame mode for packet based protocols (Ethernet, PPP, and RPR)
Transparent mode for other protocols
LCAS: LCAS is used for the survivability options of next-generation SONET services and to dynamically adopt bandwidth based on customer's request. LCAS can be used with both high-order and low-order VCAT. The blend of customer satisfaction and lower operating cost makes it attractive for carriers. Use of LCAS purges the need for manual provisioning and enables service upgrade.
VCAT: VCAT enables SONET/SDH transport pipes to be right-sized for Ethernet transport. The technology allows SONET/SDH channels to be multiplexed in arbitrary arrangements. For SONET, virtual concatenation rates are designated by STS-m-nv for high order virtual concatenation and by VT-m-nv for low order virtual concatenation.
For SDH, the rates are designated by VC-m-nv.
RPR: RPR is used to integrate efficiently the bandwidth and the packet services support.
A Comparison of Ethernet versus Ethernet-over-RPR includes
Ethernet is designed for point-to-point and mesh topology networks, not ring topologies
Ethernet has a comparatively less number of protection mechanisms
Ethernet has comparatively low fairness policies for sharing ring bandwidth

Packet over SONET (POS): It is the traditional way of transporting packet data directly without an ATM layer. POS encapsulates frame/packet-based protocols like PPP (point-to-point protocol), Frame Relay, and Ethernet over HDLC (high-layer data link control) within SONET; it cannot differentiate the separate packet streams on the link to allow per-stream traffic engineering, protection, and bandwidth management.

Key elements in Multi Service over SONET/SDH are:

Data optimization of the SONET/SDH transport layer
Quality of service (QoS) to achieve service-level agreements
Opportunities in packet based services over SONET/SDH

Next-generation SONET/SDH Technologies

Agilent technologies Inc. leads in terms of Next generation SONET/SDH products. Some of the key products of Agilent include OmniBER OTN, OmniBER XM and N2X transport solution. Agilent's N2X tester combines the edge service testing with carrier-grade infrastructure setting. OmniBER OTN is the only instrument to offer GFP, VCAT, LCAS, Ethernet payload and measurement capabilities.

EXFO has developed FTB 8100 Next generation SONET/SDH analyzer which gives an integrated Ethernet support. Multiple testing is eliminated by the use of FTB 8100. The FTB-8100 product family supports test interfaces ranging from DS1/E1 to OC-48/STM-16 with field-expandability to OC-192/STM-64 rates.

Net test pronounced the ease of use of Next-generation SONET/SDH analysis option for its CMA 5000 Optical Transport Analysis (OTA) application. Parameters including VCAT, Differential delay and LCAS can be easily tested by the NEM's and operators.

For the constantly evolving standards, interoperability poses a serious challenge as compatibility between the equipment and network is required. VCAT in next-generation products improves the Ethernet transport efficiency and LCAS can change the transport bandwidth required. Scalability and interoperability are the two major challenges to the Next generation SONET/SDH equipments. SONET/SDH is expected to be the premier transport protocol for the upcoming years as it has the potential to add metro services through protocol transparency, granular switching and efficient bandwidth management.

The emblematic usage of next- Generation SONET/SDH is

To split the band width between packet and Time division multiplexing (TDM) services dynamically
To endow with incremental packet bandwidth.
To label, multiplex and switch with a diminution in port counts over the Classical SONET /SDH architecture.
The chip vendors drive their SONET/SDH devices in two directions
Higher speeds, densities and power savings
Support next-generation capabilities and technologies

SONET/SDH in ASIA
There are small numbers of operators in India, East Asia, and Europe who are attempting to build networks without any SONET/SDH layer. The reason for small number of operators is that the SONET'/SDH's installed base is too large for carriers to simply walk away. The service providers are looking to buttress private line profits by adding data private lines with enhanced management and security. Major efforts for Ethernet over Optical networks have been done and this restraints Ethernet over SONET.

Ethernet over SONET/SDH is limited point to point service today, It is expected that for the carriers to takings they must shore up multiplexing and multi point services. The data private line is part of incumbent carrier strengths to support private line profits. The equipment vendors are expected to develop systems that span from customers to core, leveraging advances in traffic management, multiplexing services. It is expected that by replacing SONET/SDH add/drop multiplexers (ADMs) with multi service platforms that support Ethernet and other packet-based protocols, as well as TDM, carriers can achieve significant returns on their scarce investment.

Key elements in Multi Service over SONET/SDH are:

Data optimization of the SONET/SDH transport layer
Quality of service (QoS) to achieve target service-level agreements
Opportunities in packet based services over SONET/SDH

The major factors determining market growth of the world SONET/SDH test equipment market include:

Drivers

User demand for Ethernet-based services is the major driver for this market.
High bandwidth requirement, along with the integrated product functionality (generic framing procedures and virtual concatenation) drive the world SONET/SDH test equipment market.
Movement towards optical and data convergence is also driving demand for SONET/SDH test equipment.

Restraints

End user spending condenses demand in the SONET/SDH test equipment market.
There is a slow adoption rate of next generation SONET/SDH test equipment as users are not willing to let go off their existing equipment and hence are not upgrading.
As there is not much technological development, sale in the new test equipment market is retarded.

Challenges

The Slow capital expenditure (CAPEX) situation is dampening demand for SONET/SDH test equipment market.
The complexity of Next generation SONET/SDH test equipment poses a serious challenge to test vendors.
End user requirements challenging vendors of SONET/SDH test equipment in terms of product development. Quality of service is also representing a significant challenge for vendors.

Outlook
The SONET/SDH market experienced a downward spiral in the last few years. However, the future looks positive. The price of this equipment is in parity with asynchronous equipment and is expected to decline further. Next-generation SONET/SDH technologies are main driver for the growth of SONET/SDH test equipment market.

Key Market Participants

Key market participants include Agilent technologies Inc. (www.agilent.com)
Acterna (www.acterna.com)
Anritsu incorporation (www.anritsu.com)
EXFO (www.exfo.com)
Sunrise Telecom (www.sunrise.com)

Prathima Bommakanti research analyst, Frost & Sullivan