How Amsterdam was wired for open access fiber

Preventing fiber damage. As all fibers that terminate in a given APOP are getting close to that location, the number of fibers per meter increases. The main cause of damage to buried fibers is a (sub-) contractor hired for another type of work, for instance on water pipes, who starts to dig with a machine without the mandatory check of the cable plans. A small number of broken fibers can be repaired quite quickly, but it obviously gets difficult as the number increases. A number of precautions were taken to prevent that from happening.

First of all, the number of fibers in one bundle was limited; four bundles of ducts for entering an APOP is common. A separation of one meter between bundles and a cover net 20cm above the bundles reduces the risk of damage by machine digging to multiple bundles. In extreme cases, a shield of concrete was used above the bundles. The design of the network separates out bundles in different directions from the APOP as soon as possible to reduce the potential exposure.

Secondly, the high density fiber cables used did not go over 96 fibers per cable. If an HDPE duct with multiple high density fiber cables is broken, you can use multiple welding teams in parallel, one per cable, which is much faster than one team on a very high density cable. The SLAs on repairs range from 4 hours for a few fibers to 24 hours for major disruptions with a large number of fibers. In practice this has worked quite well. Very few damages of fiber cables have been reported, and all were in minor branches of the network.

As a thought exercise, a scenario had been developed for a catastrophe. Assume that the building where the APOP is located was completely destroyed by an airplane or bomb. What do you do? It turns out that given the availability of new electronic equipment, it is quite feasible to construct an emergency APOP and get everything connected again within 6 to 8 weeks. In the meantime, a wireless backup service could be made available using fiber connections from the surrounding FTTH areas. After all, the distances are relatively small.

October 14, 2011

Continue