Fiber-optic converters bolster nets

Bandwidth-hungry multimedia applications, such as audio and video, have increased the need to move more traffic at higher speeds on underlying network infrastructures. These demands require the cost-effective deployment of fiber-optic communications technology.

In fiber-based networks, the basic function of the transmitter in the optical transceiver is to reliably convert serial electrical signals inside the equipment into serial optical signals that are then focused and sent across fiber-optic cable. On the receiving end, the transceiver must reliably convert the optical signal back into the electrical domain. The transceiver must also recover the original signal even if there has been distortion along the fiber transmission path.

Over the past few years, two implementations, with different physical form factors, have been vying for market acceptance in optical networks.

The first optical technology, Gigabit Interface Converter (GBIC), integrates the transmit and receive functions needed to convert between serial-electrical and serial-optical signals, simplifying switch and hub design.

The second optical technology is commonly known as one-by-nine (1x9) and is implemented on a solderable device with one row of nine electrical interface pins. This hard-soldered component is used to provide the physical-layer features on a printed circuit board subsystem, which must then be integrated into the overall system. While potentially economical for use in individual desktop-oriented subsystems, the use of hard-soldered 1x9s in network-centric equipment, such as switches, hubs and repeaters, greatly reduces configuration and service flexibility.

The industry-driven GBIC specification defines a common form factor and electrical interface. This pluggable transceiver module lets system builders and net executives configure, incrementally populate and cost-effectively reconfigure fiber links as required. Initially targeted to support Fibre Channel data networks, the GBIC standard was quickly adapted for use with Gigabit Ethernet installations, as well.

By providing hot-swap interchangeability, GBIC modules give net administrators the ability to tailor transceiver costs, link distances and configure overall network topologies to their requirements. GBIC support also leaves the door open for changing the network without the wholesale replacement of system-level boards.

The use of GBIC transceiver modules reduces overall system deployment and inventory costs because a single form factor can be used for all transceivers. Network executives are not forced to buy fully populated switching equipment. They can purchase GBIC modules to configure their system incrementally, and the service/maintenance functions can be mixed and matched on the optical transceiver components on an as-needed basis.

The latest version of the GBIC specification goes further to support the concept of embedded "serial ID" data for each transceiver device. Using an on-module EEPROM, a GBIC module can provide the system with information regarding its vendor, part number, standards supported, transmission distances, etc. Extended data fields can contain details such as serial numbers and manufacturing date codes. When a new hot-swappable GBIC module is plugged in, this embedded ID information enables the switch to immediately check its status and determine if the module is qualified for use within the switch and/or appropriate for the media link.

The on-module ID information and fault-detection signals also open the door for remote diagnosis and configuration analysis across a network.

Network administrators could conserve precious staff time by remotely checking the capabilities of each GBIC port on a switch that is experiencing problems, potentially identifying incompatible or malfunctioning modules without an on-site service call.

GBIC specs
684K PDF file.

Cielo GBIC products

Methode Electronics GBICs