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Host Link Failure Detection

Introduction

If the CSP detects a failure in the host link, all spans/channels are brought out of service with the Host Link Failure Detection feature.

Important! W hen the host reconnects all of the channels will be out of service and it is the host responsibilty to bring the channels back in service.

Determining HLF

The CSP determines the integrity of the host link by monitoring host acknowledgments to Poll messages. You must enable polling to use the Host Link Failure Detection feature.

If the host does not acknowledge two consecutive Poll messages, the CSP initiates a timer. If the CSP does not receive an acknowledgment from the host before the timer expires, the CSP resets its Ethernet receiver.

Configuration

You configure Host Link Failure options using the System Configuration message.

Data[1] configures the CSP response to Host Link Failure:

0x00 - Bring all channels out of service

0x01 - Bring all channels and spans out of service

Data[2,3] configures the Failure Confirmation Timer.

Process

When the CSP detects a host link failure, it responds according to one of two options set by the host and sends an Alarm message to the host to report the failure (Alarm Type: Card 0x02, Alarm Number: 0x10).

If the host link failure is related to CSP hardware, it is resolved when the Ethernet receiver is reset. If the host link failure is not related to CSP hardware, it may have been caused by slow host processing.

If this is the case, you should consider increasing the polling interval. Slow host processing is most evident during the boot-up cycle. This alarm may also indicate that the host is not sending messages to the CSP. If this is the case, the CSP will have stopped sending responses (because there are no host messages to respond to).

A computer, attached to the Excel platform through an RS-232 or Ethernet link, from which you run the telecommunications application that controls the Excel platform.
The protocol used in most local area PC networks. Typically, most Ethernet networks support data transmission speeds up to 10 Mbps, but 100 Mbps is also possible.