Hubs
10
T10000: Interface Reference Manual • January 2011
• E20425-01
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Hubs
Because of the fast growth and the increase in demand of fibre channel
attachments, hubs can provide cascading (multiple) loops within a fibre
channel network. StorageTek tape drives are designed to use hubs to provide
for an arbitrated loop which provides the following capabilities:
•
Centralizes the attachment of the tape drives within the arbitrated loop
•
Establishes connections with either copper or fiber optic cables
•
Provides translation of physical media (such as copper to optical fiber)
•
Provides an external power supply for the port bypass
•
Provides port bypass functionality for port failures
•
Allows cascading to increase tape drive and initiator attachment
•
Supports the ability to power-on and -off, install or de-install tape drives
•
Creates a central point of port management and monitoring of the drives
•
Extends the distances between tape drives and initiators
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Giga-Bit Interface Converters
Hubs use Giga-bit Interface Converters (GBICs) to provide the physical
connection to the tape drives.
GBICs connectors are available for:
•
High speed serial data (HSSDC)
•
Copper, 9-pin shielded “D” (DB9)
•
Shortwave non-OFC
•
Longwave laser
These GBICs comply with ANSI Fibre Channel physical layer requirements.
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Considerations
Jitter is a consideration when selecting, installing, and configuring hubs within
a Fibre Channel network. Jitter is the deviation of timing of an exchange.
The accumulation of jitter occurs and continues to grow within a chain of
repeaters. As a signal is input to a repeater, jitter is not removed from the clock
and is transferred to the data at the output. At some level within the network,
jitter could exceed the allowable limit causing excessive errors. Assuring that
there are NL_Ports within the loop to reclock the signal, jitter will be minimized.
Loop Port State Machines (LPSM) are required to control the operation of the
loop and ensure Loop Initialization Protocol (LIP) is executed whenever a
reset or power-on occurs.
Summary of Contents for Storage Tek T10000
Page 14: ...Tables xiv T10000 Interface Reference Manual January 2011 E20425 01...
Page 18: ...What s New xx T10000 Interface Reference Manual January 2011 E20425 01...
Page 82: ...Private Loop SCSI Target Discovery 64 T10000 Interface Reference Manual January 2011 E20425 01...
Page 286: ...Glossary 268 T10000 Interface Reference Manual January 2011 E20425 01...
