Iris Group companies unveil new architecture to scale optical carrier networks from access through long haul

May 14, 2001
May 14, 2001--Four startups working together as the Iris Group have introduced a new optical network architecture that lets telecommunications carriers scale their networks all the way from the customer premise to the long haul, attaining transport and switching speeds of 40-160 gigabits per second and beyond on existing fiber infrastructures.

Four startups working together as the Iris Group have introduced a new optical network architecture that lets telecommunications carriers scale their networks all the way from the customer premise to the long haul, attaining transport and switching speeds of 40-160 gigabits per second and beyond on existing fiber infrastructures.

The Optical Data Network Hierarchy (ODNH) incorporates five architecturally related network elements corresponding to the hierarchical levels of an end-to-end optical data network: customer premise, metro access, metro core, packet core and long-haul transport. The five devices operate under a common management platform, moving traffic at progressively increasing rates through larger and larger optical pipes across the network.

The ODNH architecture is based on open industry standards for data, optical transport and internetworking. ODNH-based equipment -- from both Iris Group members and other vendors who choose to build to this architecture -- is designed to help carriers reduce capital and operational expenditures by optimizing the core network and increasing the ability to manage, access and differentiate services.

The Iris Group includes Metera Networks, an access/metro systems developer; Coree Networks, a core packet switching systems developer; Latus Lightworks, a long-haul optical backbone systems developer; and Iris Labs, a design laboratory for intellectual property and network management software. The companies will conduct technology demonstrations at SuperComm in Atlanta June 5-7, with individual product introductions occurring later this year and throughout 2002.

Optical Channel Concatenation: Breaking Down Wavelength "Walls"

A key technology innovation behind ODNH is optical channel concatenation, which combines the capacity of multiple optical channels, or wavelengths, into a single high-speed pipe of up to 40-160 Gbps or greater called a Superchannel. This technique sends bits across multiple optical channels simultaneously, in effect breaking down wavelength "walls."

A Superchannel made up of concatenated optical channels is mapped to one or more WaveBands, content-transparent slices of the optical spectrum that, for transport purposes, are treated as individual units. WaveBands are independently added or dropped at inline sites and routed optically at optical junction sites. With ultra-large-granularity WaveBands, a large traffic payload for the first time can have a combined transmission rate greater than the rate of any of its individual wavelengths. Optical channel concatenation is being submitted for consideration as a standard by the T1X1 Technical Subcommittee of Committee T1. Optical channel concatenation counters the mistaken notion that optical networks require huge, complex, wavelength-granularity cross-connects, sometimes as large as tens of thousands of ports. In a typical carrier network, large amounts of traffic are typically being transmitted to a fairly limited number of destinations; i.e., many wavelengths are running in parallel along just a few routes. It is therefore much more efficient to create fewer bigger pipes than to use many slower pipes: the network with the smallest number of ports operating at the highest possible rates is the simplest and easiest to manage.

Growing Pipes in Two Dimensions: Within and Across Wavelengths

H. Michael Zadikian, Iris Group founder, said, "Up to now the optical industry has used the technique of concatenating SONET 51-Mbps STS-1 bit streams in the time dimension to create progressively faster data pipes for packet switches: STS-3c for 155 Mbps, STS-12c for 622 Mbps, STS-48c for 2.5 Gbps and STS-192c for 10 Gbps. But time concatenation is inherently limited by the bounds of the transmission rate within a wavelength. The Iris Group has come up with a way to increase pipe size in two dimensions: time concatenation within a wavelength and optical channel concatenation across wavelengths. In this manner, for instance, a two-dimensionally-concatenated ("cc") bit rate across 16 10-Gbps optical channels would yield a true 160-Gbps channel OC-3072cc. This approach enables pipe size to grow independently of transmission rate advances and their associated economics, which historically have evolved very slowly."

ODNH Network Elements: Two Core Devices, Three Access/Metro Devices

ODNH specifies a set of five highly integrated architectural elements. Types 1, 2 and 3 are access/metro devices; Types 4 and 5 are core devices.

Type 5 device (Latus Lightworks): Optical Data Transport Node (ODTN)

This optical transport layer device provides ultra-high-capacity transmission in the core of the network, sending signals over great distances without regeneration. A key configuration of the ODTN is the WaveBand Optical Add/Drop Multiplexer, which provides a streamlined, manageable means of routing WaveBands across the optical transport network without compromising support for traditional SONET OC-192 services. Sophisticated network topologies are supported without the need for massive optical cross-connects.

Type 4 device (Coree Networks): Optical Data Core Node (ODCN)

This high-capacity core packet switch interfaces to traditional STS-192c streams and OC-768cc/OC-3072cc Superchannels. Instantaneous traffic engineering-based recovery is handled by the data-aware device through the intelligent distribution of packet traffic over dual diverse paths rather than standby idle paths in the transport layer; this eliminates the need for complex optical-layer, wavelength-granularity restoration schemes. Superchannels from the ODCN are mapped onto WaveBands and routed across the long haul by Type 5 devices, or carried by generic OC-192 transport systems.

Type 3 device (Metera Networks): Optical Data Distribution Node (ODDN)

The ODDN addresses the metro traffic bottleneck, providing capacity and port speeds at levels sufficient to perform aggregation across large, multiple-ring MANs. Traffic from Type 2 devices (described below) is collected by the ODDN, which provisions and bandwidth-manages it before handing it off to the Type 4 core device. As metro traffic levels grow even further, network economics will enable this Superchannel-capable metro device to take advantage of the optical channel concatenation technique developed for the core and long-haul (Type 4 and 5) devices.

Type 2 device (Metera Networks): Optical Service Line Access Multiplexer (OSLAM)

The OSLAM's role as a critical metro-area, access/central-office service management platform can be compared to the role of the subscriber management system in broadband access environments. Working at layers 1, 2 and 3, the OSLAM aggregates packet-switched and other traffic over individual gigabit Ethernet and OC-n interfaces onto faster SONET or DWDM backbone ring or mesh networks.

Type 1 device (Metera Networks): Optical Service Line Terminator (OSLT)

This customer-premise platform cost- effectively multiplexes "last mile" legacy, Ethernet and TDM facilities onto a single fiber (with optional protection fiber) for management by the Type 2 OSLAM. This eliminates a customer's need for multiple parallel facilities to separately support copper and fiber, or voice, data and video applications.

Service management software runs across all three metro network elements, working with Iris Labs ODNM network management capabilities (described below) to provide highly sophisticated service management and delivery. End-to-End Network Management Across Five ODNH Devices The Optical Data Network Management (ODNM) architecture was conceived by Iris Labs to give service providers common capability across all five ODNH device types. It facilitates high-speed service creation and delivery by integrating the functions of element and network management that are usually managed by distinct, non-integrated tools.

The standards-based ODNM provides a common development platform for Iris Group equipment vendors to build vendor-specific element-management systems; it can be custom-tailored to address specific market or customer parameters, such as fault-correlation rules and service creation. The ODNM architecture also provides end-to-end, multi-vendor network management, relying on the distributed intelligence in the five ODNH device types and their element management systems to orchestrate their activities. The complex relationships between logical entities (e.g., TDM circuits, VPNs) and physical ones (e.g., fibers, wavelengths) are mapped to accurately provision available bandwidth between all network paths.

As an open architecture management platform, ODNM has SNMP, TL1 and CORBA data interfaces, allowing it to manage a mix of ODNH and non-ODNH devices.

About The Iris Group:

The Iris Group, an alliance of four independent but cooperative startups, was formed in mid-2000 to develop a new optical network architecture that provides unprecedented scalability for data-centric carrier networks. Three of the firms are equipment companies: Metera Networks (Richardson, Tex.) develops metro/access systems; Coree Networks (Tinton Falls, N.J.) develops core packet switching systems; and Latus Lightworks (Richardson, Tex.), develops optical backbone systems. The fourth, Iris Labs (Plano, Tex.), is a design laboratory developing key intellectual property and network management software. For more information, visit Iris Group web sites at, and and

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