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Interfaces:
Fibre Channel Connections
Single-mode
Fibre, Multi-mode Fibre, and four kinds of copper cables are defined
in the Fibre Channel standard allowing one of the most flexible
storage and data transfer communication standards available. The
most popular implementations of Fibre Channel over copper are twin-ax
using DB-9 or HSSD connectors. Point-to-point is used in simple
scenarios such as attaching a RAID array or other storage device
to a single system. Point-to-point does not require a hub or loop
as only two devices are involved.
To
convert a copper interface to an optical interface, a Gigabit Interface
Converters (GBIC) or interface converter is used. A normal GBIC
usually has a HSSD copper interface, and standard interface converters
usually incorporate a DB-9 copper connection.
- Connectors
There are a number of connectors available for Fibre Channel
interfaces. The most popular are listed below:
- SC
connector: this is the standard connector for Fibre Channel fibre
optic cables. It is a push-pull connector and is favoured over
the ST connector in many implementations. If the cable is pulled,
the tip of the cable in the connector does not move out, resulting
in loss of signal quality.
- ST
connectors: these are vaguely similar in design to quarter inch
audio jacks, with a simple plug-in male/female connection that
relies on the friction between jack and plug to hold into place
and has no additional securing device. ST connectors however,
do have the advantage of being simpler and cheaper to install.
- Copper
connectors usually take the form of either standard DB-9 connectors
- simple plugs with 9-pins, or HSSD connectors.
Fibre
Multi-mode Cable
Multimode cable is dominant for short distances of 2 Km or less.
Multimode has an inner diameter of 62.5 or 50 microns, allowing
light to enter the cable in multiple modes, including straight and
at different angles. The many light beams tend to lose shape as
they move down the cable. This loss of shape is called dispersion
and limits the distance for multimode cable. Cable quality is measured
by the product of bandwidth and distance. Existing 62.5 micron FDDI
cable is usually rated at 100 or 200 MHz /Km, providing gigabit
communications up to 100 or 200 meters.
Fibre Single Mode Cable
Single mode cable is used for long distance cable runs. Its
distance is limited by the power of the laser at the transmitter
and by the sensitivity of the receiver. Single mode cable has an
inner diameter of 7 or 9 microns and only allows a single ray of
light to enter the cable. Therefore, with single mode cables there
is no dispersion. Single Mode fibre optic cabling naturally carries
a price premium for this added functionality.
Related
topics:
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