FW 05.01.00 and SW 07.01.00 HP StorageWorks SAN High Availability Planning Guide (AA-RS2DC-TE, June 2003)

Physical Planning Considerations
118 SAN High Availability Planning Guide
Consider the following when determining the number and type of each transceiver
to use:
■ Distance between a director or switch and the attached Fibre Channel device,
or between fabric elements communicating through an ISL.
■ Cost effectiveness.
■ Device restrictions or requirements with respect to existing fiber-optic cable
(multimode or single-mode).
Data Transmission Distance
Data transmission distance is the primary factor governing the choice of
transceiver type and optical fiber. If the transmission distance is:
■ Less than 150 meters; multimode or single-mode optical fiber and any type of
optical transceiver can be used.
■ Between 150 and 300 meters; 50/125-micron multimode or single-mode
optical fiber and any type of transceiver can be used.
■ Over 300 meters; only single-mode optical fiber and a longwave laser
transceiver can be used. A 62.5 micron cable is only supported for the use of
existing cable plants. HP recommends the use of 50 micron cables for new
installations.
Variables such as the number of patch panel connections, link speed, grade of
fiber-optic cable, device restrictions, application restrictions, buffer-to-buffer
credit limits, and performance requirements can affect transmission distance.
Cost Effectiveness
Cost is another factor governing the choice of transceiver type and optical fiber.
Shortwave laser transceivers and multimode cable offer a less expensive solution
if data transmission distance is not critical.
Device or Cable Restrictions
The choice of transceiver and cable type may be restricted or dictated by:
■ Device restrictions — Some devices may be restricted to use of only one type
of transceiver (shortwave or longwave). Refer to the supporting
documentation delivered with the product for information.
■ Existing cable restrictions — The enterprise may contain only one type of
fiber-optic cable (multimode or single-mode), and the customer may be
required to use the existing cables.