Ah, the romance of the railroad. Conductors shouting “all aboard”, watching the countryside whizz by, dining cars and sleeper cars, boxcars, the Orient Express, bullet trains, chasm-spanning bridges, the clickety clack of the rails, clang clang at the crossings, and the engineer waving from the caboose. As we near the two hundred year mark of the first passenger train in 1825, we can observe that railways, our oldest modern means of mass transportation, are as strong as ever.
With over 1 million kilometers of track globally, enough to circle the earth 25 times, railways are now investing in digitalization to keep up with the times. This includes multiple initiatives like FRMCS (Future Railway Mobile Communication System) which modernizes communications and control with high-speed radio links along the trackside, new automation systems for improved safety and maximizing the use of railway resources, expanded CCTV surveillance, and broadband streaming and infotainment services for passengers.
To transport the expanded communications traffic, railways are in parallel modernizing their IP and optical communications networks. At Ribbon, we are fortunate to support this modernization with nearly twenty railways around the world, including Deutsche Bahn, the largest railway in Europe.
Railway communications networks have unique needs. They must transport a mix of mission-critical and regular communications traffic, mitigate against outages and security breaches that cause national headlines, and deploy equipment in harsh environments and unmanned sites. Some railways, because of their extensive rights-of-way for fiber, also have the opportunity to resell bandwidth as carrier-of-carriers or UTelcos.
With these imperatives in mind, and based on our extensive experience, here are the six considerations we recommend that railway operators investigate before embarking on a journey to modernize their IP Optical network infrastructure.
- Flexible Service Aggregation. Like railway feeder lines, railway communications networks must aggregate multiple types of lower speed traffic from many endpoints distributed across stations, tracks, and yards. Technical solutions exist both at the packet layer using statistical and deterministic multiplexing IP routers, and at the fixed slot optical layer using OTN multiplexing. Understand the pros and cons of each approach for mixes of services and geographies, and consider that a complete solution often combines both.
- Scalable-Resilient Optical Backbone. These are the major trunk lines of the communications network. Minimum bandwidth today is 100G wavelengths, and a solution should be able to scale smoothly to 200G/300G/400G as traffic grows. For optimal traffic flow of services to data and control centers, it should be possible to groom lower speed services traffic onto the wavelengths, and to route the wavelengths flexibly end-to-end under software control. For maximum resiliency against failures, the backbone should combine protection switching on critical paths with dynamic restoration using shared facilities on less critical sections.
- Round the Clock Monitoring. As the communications network is tied closely to railway operations, in most cases it is essential to monitor the network and be able to address critical problems 24/7/365. While railway operators can use a network management system to do that themselves, they should inquire about supplementing this with a “NOC-as-a-service” provided by the communication network supplier, at least for off-normal work hours. Also, besides monitoring the IP optical network itself, consider mechanisms to monitor the physical fiber running alongside the tracks, including an ability to pinpoint the location of breaks quickly.
- Traffic Management and Multi-tier Security. Not all traffic is the same. A network solution should be able prioritize the flow and availability of mission critical control traffic, as well as provide a hard separation of leased bandwidth. The IP optical network controller should have multiple levels of administration access, and include mechanisms to mitigate against human error misconfiguring or disabling the network. The railway operator should also consider adding cyber security applications that alert of illegal access attempts and hacking attacks.
- Smooth Technology Migration. It is rare that network modernization occurs all at once. Upgrades of IP and optical functionality usually occurs in stages, over a period of time for different sections of the network. To accomplish this smoothly, it is essential that various generations of technology can reside side-by-side, or interoperate, using capabilities like circuit emulation services (CES) and alien wavelengths.
- Future-proof Technologies. Railway operators expect their systems to support an extended life cycle of 15 to 30 years. Therefore, the choice of networking technology should reflect a maturity of market adoption, a path to support network expansion and new services, and be maintainable and upgradeable over time without forklifts.
In summary, modernizing a railway communications is a non-trivial mission. There are multiple technology approaches, and associated considerations for control, security, availability, and migration. The solution must balance performance, cost, and an ability to evolve smoothly into an increasingly digital future. It is important to seek out a solution supplier that is not married to a singular approach. Seek out a supplier that understands the needs of railway operators and acts as a trusted adviser and partner when laying out and discussing solution alternatives