Fiber Backbone Security Underground vs. Aerial

Charles Carino

This whitepaper, entitled Fiber Backbone Security Underground vs. Aerial, addresses security issues relating to these two cabling installation methods. Specifically, this paper explores issues relating to physical security of fiber optic telecommunications backbones as they pertain to the terrorist threat.

Common Misconceptions

When addressing Fiber Backbone Security Underground vs. Aerial the first thought that many people have is that buried cable is more secure. Covered by dirt, asphalt or concrete, it would seem to take some effort for a terrorist to locate where the buried cable is, and then to dig down to gain access to it.

In contrast, aerial cable, being suspended in the air, seems an easy target for any weapon fired from the ground, or anyone capable of climbing a utility tower or pole.

However, upon closer analysis, aerial installations actually provide more security. This has to do with fiber's tremendous bandwidth, the relatively low cost of aerial installations, and the alternate cable routes that are possible with this type of installation.

Security Strategy - Minimization vs. Prevention

The analysis of Fiber Backbone Security Underground vs. Aerial may seem purely academic, given that there are so many places that terrorists can access fiber in a huge national network. Even underground systems provide access via manholes, hand holes, above ground splice pedestals, and so forth. Prevention, at least at this point in time, appears to be impossible.

Since we can't prevent attacks, the security strategy must be to minimize the disruption that would result from such attacks. The way do to this is to reroute data from destroyed fiber optic cables to other fiber optic cables and networks that remain intact. The main reason this is possible is because of the tremendous bandwidth of fiber, and it's capacity to take on the additional load.

Some of this alternate routing capability already exists in the aerial fiber optic cable that is currently in place. Furthermore, today's telecommunications carriers are building even more aerial capacity by partnering with power companies and sharing their rights of way. These carriers are motivated by the fact that underground utility corridors are getting more crowded, and obtaining rights of way for buried cable is getting increasingly expensive. In contrast, aerial installations and repairs are faster, easier and less costly. According to most estimates, aerial construction is as much as 40 to 50 percent less expensive than the underground alternative.

Creating a like number of alternate cable routes underground would likely be an impossible task, considering the amount of digging and boring that would be necessary, not to mention disruption to above-ground facilities.

Some Issues Remain

Thousands of alternative cable routes aren't helpful if there is no disaster recovery plan in place, which includes procedures for rerouting telecommunications in the event of a catastrophe. Unfortunately, only the telecommunications carriers know the physical route that data takes through their networks. For various reasons, including competitive concerns, carriers have been very reluctant to share this information.

Federal authorities are now pressuring carriers to release this information so that effective disaster recovery plans can be developed.

Another major issue is that there are some fiber backbones in the U.S. where huge amounts of data are channeled with no redundant routing available. For example, there are two bridges over the Mississippi River that carry most of the bandwidth distributed along the eastern U.S. At present, no alternate cable route exists. This is one instance where buried cables could, in fact, prove beneficial by providing alternate fiber optic distribution channels under the riverbed.

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