IBM System Storage DS4000, Hardware Maintenance Manual

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Chapter 2. Type 3523 Fibre Channel Hub and GBIC
Note: The problem determination (PD) maps found in the IBM TotalStorage DS4000
Problem Determination Guide provide you with additional diagnostic aids.
The type 3523 fibre channel hub and Gigabit Interface Converter (GBIC) are
compatible with the following IBM products:
v Fibre channel PCI adapter (FRU 01K7354) (see Chapter 3 on page 11)
v IBM DS4000 host adapter (FRU 09N7292) (see Chapter 4 on page 13)
v
Type 3526 fibre channel RAID controller (see Chapter 6 on page 21)
The IBM fibre channel hub is a 7-port central interconnection for Fibre Channel
Arbitrated Loops (FC-AL) that follow the ANSI FC-AL standard. Each fibre
channel hub port receives serial data from an attached node and retransmits the
data out of the next hub port to the next node attached in the loop. Each reception
includes data regeneration (both signal timing and amplitude) that supports
full-distance optical links.
The fibre channel hub detects any loop node that is missing or is inoperative and
automatically routes the data to the next operational port and attached node in the
loop. LED indicators provide status information to indicate whether the port is
active or bypassed.
Each port requires a GBIC to connect it to each attached node. The fibre channel
hub supports any combination of short-wave or long-wave optical GBICs. The
GBICs are hot-pluggable into the fibre channel hub, which means you can add host
computers, servers, and storage modules to the arbitrated loop dynamically
without powering off the fibre channel hub or any connected devices. If you
remove a GBIC from a fibre channel hub port, that port is automatically bypassed.
The remaining hub ports continue to operate normally with no degradation of
system performance. Conversely, if you plug a GBIC into the fibre channel hub, it
is automatically inserted and becomes a node on the loop if valid fibre channel
data is received from the device.
Data transfer within the fibre channel hub is implemented in serial differential
Positive Emitter Coupled Logic (PECL) AC coupled logic. Each fibre channel hub
port monitors the serial data input stream as well as the GBIC connected to it.
The following conditions cause the fibre channel hub to bypass a port:
v TX_FAULT: Detects a GBIC transmitter fault
v
RX_LOS: Detects a loss of received signal amplitude from the device
v MOD_DEF: Detects the absence of a GBIC
The fibre channel hub circuitry detects off-frequency data, excessive jitter, or
inadequate edge transition density on a per-port basis. The fibre channel hub uses
the standardized AMP SCA2 20-pin connector to implement hot plugging. Surge
currents, caused by hot plugging, are minimized by slow-start circuitry and a
pin-sequencing procedure on the GBIC. Electrostatic discharge (ESD) transients are
minimized by means of sequenced connector contacts.
The fibre channel hub includes a universal power supply that can operate from 95
to 250 V ac and from 50 to 60 Hz.
© Copyright IBM Corp. 2004
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