Dark Fiber Testing and Debugging Process

Isolating Dark Fiber Service Issues

Dark Fiber is where ACD provides physical fiber cable connectivity between two or more sites. ACD generally does not operate or maintain the equipment for the customer.

Point of Demarcation and Responsibility

ACD Responsibility:

1. Fiber Cable that is outside of the building
2. Fiber Cable coming into the building; and is prior to the fiber termination box.
3. The fiber termination box, and the connectors directly attached to the fiber termination box.

Customer Responsibility

1. Patch cables from the fiber termination box to their equipment.
2. Network Switches/Routers
3. Optics.

When a customer reports an issue with dark fiber we need to know the nature of the problem reported:

1. Outage - no connectivity between sites.
   1. Is the outage affecting all fibers between a site or only specific fibers?
   2. Need to know which fibers?
2. Transmission Errors Transmission occuring, but CRC errors on equipment.
   1. Is this occuring on all fibers between a site or only specific fibers?
   2. Are the errors on both on the TX and RX sides of the circuit?
3. Intermittent Trasmission Errors Transmission is occuring, but CRC errors on equipment is intermittent
   1. How often are the CRC errors occuring, i.e. is there a pattern or cycle to the errors?
   2. What time of day? Any pattern?
4. Low Light Level is low on fibers?
   1. What is the db attenuation of the fiber strand that is having a problem?
   2. Is this occurring on all fiber strands?

ACD Testing Procedure

In order to test dark fiber strands that are having issues, we need to disconnect equipment. There is no way to test fibers without disconnecting equipment, therefore any request should be with the understanding that it will be service affecting. If there are spare adjacent fibers that are on the same cable, we can test these for continuity of the overall fiber cable. If the spare cables are functional, equipment can be reloacted to the spare cable.