Selectel’s Fiber-Optic Network
The quality and level of services provided by any data center depend largely on its telecommunication channels. We always pay special attention to issues regarding connectivity: almost as soon as our first data center opened in 2008, we started construction on our own fiber-optic line. Today, these lines span a total of over 230 kilometers. Thanks in large part to this network, we can provide our clients with uninterrupted Internet connections. In this article, we’ll take a detailed look at our fiber-optic lines.
Five of our data centers are located in St. Petersburg and the surrounding area (Tsvetochnaya 1 and Tsvetochnaya 2 are located in the city proper, and Dubrovka 1, Dubrovka 2, and Dubrovka 3 are located in Dubrovka). All of the data centers are connected in a single data network:
Tsvetochnaya
Tsvetochnaya 1 is our main communications hub. The data center has three cable lines: two run through underground municipal cable ducts and another along overhead lines.
All of our cables run under a raised floor to switch racks, which is where our optical splitters are. A fiber optic splitter, also known as a cross connect or optic coupler, is a device that routes optic cables to equipment.
The splitter is a metal box installed in a rack. The cable connects to the back or side of the box, and panels with optic connectors are located on the front. We use FC optic connectors to provide a more reliable connection.
The photo above shows one of the seven splitters we have installed. This is the backbone of our network. It’s this splitter that maintains the connection between all of our data centers.
Tsvetochnaya houses two cross connect racks for further routing to client equipment. Our clients include almost all of the Internet service providers in St. Petersburg: RunNet, Retn.Net, OBIT, Rascom, Eurotel, Komstar-OTS, Severen Telecom, Covintel, GlobalNet, Eltel, Filanco, Prometey, TeliaSonera, Rostelecom, etc.
All of the connections in Tsvetochnaya are made using fiber optic patch cords that run along cable baskets. We mainly use single-mode connections to ensure stability, regardless of the distance between racks.
Dubrovka Data Centers
Three of our data centers (Dubrovka 1, Dubrovka 2, Dubrovka 3) are located in the town of Nevskaya Dubrovka, approx. 30 km east of St. Petersburg. The data centers are connected by cables that run along transmission towers and cable ducts.
The Dubrovka data centers are connected by two fiber optic lines to Tsvetochnaya 1, the citywide communications hub at Borovaya 57, and the Internet exchange point at Bolshaya Morskaya 18.
These lines run along transmission towers and railroad overhead lines in the Vsevolozhsky region. Fiber optic junction boxes are mounted at railroad stations to connect to our clients.
The cables that run along transmission towers and overhead networks are all-dielectric self-supporting cables (which are designed specifically for transmission towers). The cables that run along the cable ducts are lashed optical attached cables and optical ground wires (which are designed specifically for cable ducts and pipes).
Running cable along overhead railroad lines.
The optical distance of communication lines from Tsvetochnaya to Dubrovka is 57 km for our primary line, and 78 km for our reserve line. The overall loss is 10.5 dB and 15.5 dB respectively.
Monitoring and Fault-Tolerance
Once in a while, our fiber optics may get ruptured or damaged. This is often caused by careless construction or repair work, when bulldozers or other machinery harms the cables.
There has even been a case (which also happens to be the biggest catastrophe in the history of Selectel) when unknown vandals actually shot our cables with air rifles.
A shot cable
A cable damaged by an excavator
Regardless of the situation, we always meet the restoration time stated in the service level agreement (8-10 hours from the moment we are informed of the incident), and this is keeping in mind that our cables are 96 to 114 fibers thick. How do we manage this?
The damage-tracking procedure is fully automated.
We monitor the lines’ condition using the NQMSfiber fiber-optic monitoring system by EFXO. This lets us keep track of the status of our cables 24/7/365. Remote testing units (RTU) are installed at key points, which let us run continuous (once every 15 seconds) integrity and degradation checks.
The system is managed from a simple, easy-to-use online interface. If any defects are detected, the system instantly sends out notification via email and/or SMS.
Once a message has been received, we log onto the system and look through the following information: incident type (rupture or degradation), date and time of incident, and distance to incident location. From the online interface, we can also look over a reflectogram, which can help determine the interval as well as the direct and return losses before and after the event.
All of this helps us remotely (i.e. by simply looking at the computer) determine where the damage is with an accuracy of several meters. Our emergency team is dispatched to the site and immediately starts restoring connectivity between data centers.
We have several warehouses with spare parts and equipment located in St. Petersburg and the surrounding region. This lets us respond to emergencies and repair damages as quickly as possible.
We always have the supplies needed to perform maintenance on our communication lines: monitoring and measurement equipment, cleaning materials for optic sockets, etc.