1. What should I know
about speed and duplex settings when configuring
Ethernet links with Shore Microsystems equipment?
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Shore Microsystems Link
Protector® and Bypass solutions support auto-negotiation
of Ethernet link speed and duplex parameters. That said,
it is recommended that users "hard code" speed and
duplex settings for Ethernet links wherever possible.
Hard coding these parameters facilitates rapid
switchover of SM-27XX and SM-28XX port cards since all
links have fixed preset parameters and need not proceed
through an auto-negotiation process upon link failure
and switchover.
Of note, all link
interfaces (e.g. Primary, Backup, and Protected) for
Shore Microsystems port cards must be configured (or
negotiated) to the same speed and duplex settings. This
requirement ensures successful rapid switchover.
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2. If my Protected device
is connected to two separate network switches through a
Shore Microsystems Link Protector, wouldn't that cause
Layer 2 Spanning Tree and MAC address issues?
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Shore Microsystems Link
Protectors monitor a Primary and Backup connection to
the external network. Usually, this translates to
connections to Primary and Backup network switches which
operate on the MAC address of the Protected link. In
normal operation, the Protected link is connected to the
Primary link and thus the Primary switch will learn and
advertise the presence of this MAC address to the rest
of the network. SM-27XX series port cards ensure that
the Protected link can only be connected to either the
Primary or Backup switch at any one time (never both)
and thus prevent routing loops.
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3. How can Shore
Microsystems Link Protector solutions facilitate such
rapid and seamless link switchover?
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When the Primary link
fails, it is necessary for the Backup switch to
immediately learn the MAC address of the Protected
device. This ensures that network traffic bound for the
Protected device is rapidly routed through the Backup
switch and no longer through the Primary switch.
Shore Microsystems employs
patented technology to immediately notify the Backup
switch of the new network topology (namely that the
Protected device will now be reachable via the Backup
switch). Several switch vendors provide an ability to
propagate changes to the network topology in an
accelerated fashion. For example, Cisco's "Portfast"
feature curtails normal spanning tree requirements and
makes it possible to switch from a Primary switch port
to the Backup switch port without losing frames. When
paired with Shore Microsystems technology, your
Protected device can ensure a seamless switchover
following a Primary link drop.
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4. Shore Microsystems
mentions it has a Packet Spy feature to detect a "soft"
link failures, but what does that mean?
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Soft failures are those in
which the lower-level link is operational but some
higher level function is inoperable. For example, if a
switch suffers a sudden firmware crash, an associated
switch link may appear to be functioning normally but no
useful data traffic will flow. In this case, the
hardware physical (PHY) chip is still powered up even
though the firmware crash renders the switch
non-functional.
All advanced SM-27XX Link
Protector port cards now offer the Packet Spy feature to
identify these soft failures. Links are monitored for
excessive idle time; if a programmable idle link time
threshold is exceeded, the Link Protector triggers a
switchover event. For example, if a frame is not
received in 2 seconds, the link can be considered as
"failed" even though the link is still "up" in the Layer
1 sense.
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5. How should I configure
my serial console to communicate with Shore Microsystems
equipment?
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SM Product
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Baud Rate
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Databits-Parity-Stopbit
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Connector Type
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NPC with AMC
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115200
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8-N-1
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Cisco console (RJ-45)
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NPC with SMC
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9600
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8-N-1
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Rollover Cisco Console (RJ-45)
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Other
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9600
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8-N-1
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DB-9 (female DTE)
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Note: For all cases, flow control should be disabled.
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6. Does Shore Microsystems
support Auto-MDIX to compensate for reverse network
cable wiring?
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All
advanced Shore Microsystems products fully support
Auto-MDIX (e.g. SM-2701C port card). Standard technology
products (to include SM-2400X, SM-2501, SM-2501G, and
SM-2701CS port card) incorporate a limited crossover
capability, but these products do not fully support
Auto-MDIX to the IEEE standard.
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