Difference between LIT & DARK Fiber

              When you buy internet, you are buying a “LIT” service. What that means is that the provider you are subscribing to is managing the service they are providing with their own networking gear. Typically you will find that edge switch in the telco closet in the basement of the building you are at or in one of the telephone rooms. Depending on the service you subscribe to will determine what kind of networking switch is installed in the building. If you go with a broadband type of service the provider's switch will not have that much horsepower to handle much more than a 100Mb and you will be sharing that with other subscribers in the area you are in. When you buy a “dedicated” service the providers networking gear will be able to handle 1Gb and in some cases up to 10Gb of synchronous service.

              Looking at dark fiber service the provider will have their dark fiber box(Fiber Distribution Panel) in the MPOE of the building and sometimes a “LIT” networking switch as well to provide both dark and lit fiber service. When you buy dark fiber it comes in pairs. One to transmit and the other to receive data. The great thing about dark fiber is that the customer is able to manage the fiber themselves with their own networking gear. This gives them more security in that they can manage their own firewalls and switches and configure them how they want. The dark fiber between each piece of networking gear is for that customer only and they can transfer up to 100GB of data depending on what kind of hardware they purchase. Or split it up into multiple 10Gb lines for different applications such as video or voice.

              One thing to also keep in mind about dark fiber is that it is a point to point service. So, you need to have a second location such as a sister office or a datacenter. It is also distance limited and if you want to traverse more than 80km(50 miles) you will need special optical cards in your gear and regeneration equipment. Lastly, dark fiber is sold at a higher premium than lit fiber. Mainly because you can pump a ton of data over those strands of fiber future proofing the network. Thus, you really have to think about why you want dark fiber vs a lit fiber solution.


Daniel Macias – Fiber Sales Professional