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Frequently Asked Questions (FAQ)

1. What should I know about speed and duplex settings when configuring Ethernet links with Shore Microsystems equipment?

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.


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?

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.


3. How can Shore Microsystems Link Protector solutions facilitate such rapid and seamless link switchover?

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.


4. Shore Microsystems mentions it has a Packet Spy feature to detect a "soft" link failures, but what does that mean?

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.


5. How should I configure my serial console to communicate with Shore Microsystems equipment?

SM Product

Baud Rate


Connector Type

NPC with AMC



Cisco console (RJ-45)

NPC with SMC



Rollover Cisco Console (RJ-45)




DB-9 (female DTE)

Note: For all cases, flow control should be disabled.


6. Does Shore Microsystems support Auto-MDIX to compensate for reverse network cable wiring?

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.