Starting in the rack

Also: Enterprise optical boxes see the light Interactive scorecard and NetResults How we did it Sidebar: Some established vendors bow out Related links

Because these products are relatively new in the enterprise space, we wanted to provide a physical description of each box.

Each product tested supports several protocols, including Ethernet (10/100/1,000M bit/sec), SONET/Synchronous Digital Hierarchy (OC-3, OC-12), FDDI, ATM, Enterprise Systems Connection and Fibre Channel. Our test requirement called for the shelves to simultaneously support 100-Base-F (Fast Ethernet over fiber), ATM and Gigabit Ethernet.

Cisco's Metro 1500 is a cream color - a deviation from the company's traditional black and dark blue, as it is an OEM product from German manufacturer ADVA Optical. Except for the strange placement of the mounting screws under the handles, the Metro 1500 easily fit into our 19-inch rack. Each Metro 1500 shelf can support up to eight channels, and it is possible to put up to four additional shelves together using an optional band splitter module for a total of 32 channels.

The Cisco units we tested were configured with four channels per shelf. Each shelf included dual, redundant power supplies and a remote switch module (RSM). The RSM is an optional module that provides link redundancy between the shelves. Many of the optical modules in the Metro 1500 are passive devices. All the active modules, including the Wavelength Channel Module (WCM) that provides the optical inputs and outputs to the shelf, and power supplies are hot swappable.

The Alcatel Optinex 1690 is also an ADVA Optical OEM and looks identical to the Cisco Metro 1500, except for the vendor's nameplates. All of the features we found in the Cisco Metro 1500 were also available in the Optinex 1690.

Nortel's OPTera Metro 5200 supports up to eight unprotected channels and four protected channels per shelf. In Nortel parlance, a protected channel is one sent down both sides of a ring configuration between shelves. Protected channels can survive a fiber cut or link failure. Unprotected channels are sent down a single side of the ring, allowing both sides of the ring to be used for different individual channels. Protected mode offers resiliency with fewer available channels, while unprotected mode offers more channels with less redundancy. You can mix and match protected and unprotected channels on an individual channel basis. Nortel allows the shelves to be stacked to a maximum of eight per system, providing a maximum capability of 64 channels (all unprotected) or 32 channels (all protected).

Running a T-1 line or even an OC-3 connection over a single 2.4G bit/sec channel doesn't come close to utilizing the available bandwidth of the optical channel. Therefore, Nortel included a sub-rate multiplexing (SRM) card that can multiplex up to four individual sources into a single optical channel. Each input could range between 16M and 270M bit/sec, making this a nice solution for running multiple Fast Ethernet or ATM sources over a single dense wave division multiplexing (DWDM) channel.

The shelves have redundant power and diverse cooling. A telemetry function is available to measure external events such as temperature, room water levels and unauthorized access to the room. We found this feature to be attractive for limited access areas. All modules in the shelf are hot swappable.

The iTouch Communications WDM44 is small, only 1.75-inches in height and 17 pounds. While the other vendors used a modular approach with hot-swappable modules, the iTouch is a fixed configuration box. You order the product preconfigured with the specific transports and bandwidth. This makes the shelf less susceptible to damage or mistakes, but you also can't simply swap out a bad input line card.

The WDM44 is a wave division multiplexing shelf with a maximum of four channels per chassis. However, this isn't as anemic as it sounds. Enterprise networks rarely need all 32 channels offered by DWDM gear - at least not right away. The WDM44 offers a less-expensive choice for fiber exhaust.

Fritz, who is the principal network engineer for West Virginia University's Network Services department, is responsible for advanced network technology development for the WVU campus networks and has directed the university's Advanced Network Applications Lab since 1988. Fritz holds a master's degree in Electrical Engineering from West Virginia University and is the author of Remote LAN Access: a guide for networkers and the rest of us and Sensible ISDN Data Applications.

The West Virginia University Network Services test team consisting of Matthew Glotfelty, Jeff Davis and Bird Vilseck.