Sfp Optical Transceivers - McDATA StorageWorks 2/140 - Director Switch Planning Manual

Physical Planning Considerations
5
SFP Optical
Transceivers
Data Transmission
McDATA Products in a SAN Environment - Planning Manual
5-4
Shortwave laser SFP optical transceivers (1.0625, 2.1250, 4.2500, or
10.2000 Gbps) provide a connection for multimode cable with a core
diameter of 50 microns and a cladding diameter of 125 microns
(50/125 micron), or multimode cable with a core diameter of 62.50
microns and a cladding diameter of 125 microns (62.5/125 micron).
Longwave laser SFP optical transceivers (1.0625, 2.1250, 4.2500, or
10.2000 Gbps) provide a connection for singlemode cable with a core
diameter of 9 microns and a cladding diameter of 125 microns
(9/125 micron).
Consider the following when determining the number and type of
transceivers to use:
• Distance between a director or fabric 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 (multimode or singlemode) or copper cable.
Data transmission distance is a factor governing the choice of
Distance
transceiver type, fiber-optic cable type, and transmission rate. When
using multimode cable, if the core diameter or data transmission rate
increases, the data transmission distance decreases.
Link budget is another governing factor. A link budget is the
attenuation (in dB) a connection between devices can sustain before
significant link errors or loss of signal occur. When using multimode
cable, if the core diameter or data transmission rate increases, the link
budget decreases.
Cable-conversion, repeater, patch-panel, or other connections within
a link also decrease the link budget. Each connection introduces a
nominal signal loss of at least one dB through the link. Patch panel
connections (with one connection at each side of the panel) typically
introduce a two dB signal loss through a link.
Other variables such as the grade of fiber-optic cable, device
restrictions, application restrictions, buffer-to-buffer credit limits, and
performance requirements can also affect data transmission distance
and link budget.
Table 5-1 lists unrepeated data transmission distance and link budget
as a function of fiber-optic cable type and data transmission rate.