Do you have a resilient transport network?

Resilience is currently a buzzword, used in at least one conversation a day. But what does the term really mean? According to Wikipedia and other sources, in computer networks it is: the ability to provide and maintain an acceptable level of service in the face of failures and challenges to normal operation.

This morning I personally learned what resilience means and how important it can be. As usual, I logged on to work from home and started reading my mail and doing other regular morning checks. Suddenly, the fiber optic network was down! Immediately I realized that must be what the ISP meant with the warning about possible one hour downtime when moving my services to another server during the week . And I had a meeting in 5 minutes! But my resilient network came to the rescue. I used my mobile phone and connected my computer via the mobile network. In less than a minute I was back online and able to continue working.

Another larger scale example of how to increase the resiliency of a fiber network is when setting up a parallel microwave link due to the lower cost compared to a different optical path. It may not offer the same maximum capacity, but it secures connectivity for high-priority services. Last summer, on Independence Day, American Samoa experienced such a case when its 130 km long undersea fiber optic cable was suddenly cut. A long-distance microwave link was the much-appreciated backup with its 1 Gbps capacity to enable continuous communication.

Since I work with microwave products for telecommunications networks, it seems natural to focus on how these products can help our customers build more resilient transportation networks. Lately, it has become clear that it is not just occasional thunderstorms and equipment failures that may require rerouting through the network to maintain services. Other more violent events can occur and disrupt fiber optic equipment or connections.

So what does it take to make a network connection resilient?

Resiliency with dual paths, where a microwave hop is added as redundancy for the fiber.

Here are some possible solutions:

  • Alternative paths
    Alternate paths will protect against fiber breaks or other equipment failures along the original path. If dual fiber optic paths are used, they must use a different geographic path to protect the connection. Another possibility is a fiber path and a microwave path, which may be along the same geographic path since radio waves are not easily cut off.
  • Two controllers and multiple radios
    They also secure connectivity in the event of failure of vital hardware equipment.
  • Ring or mesh topologies in the network
    In this case, each site will have more than one connection to the rest of the network, preferably in different physical directions.
  • Multiple sync sources available
    Modern networks require stable time and high precision phase synchronization. Therefore, synchronization must be available from sources in different directions. Combined with local GNSS receivers at some sites, these sites can be secondary timing sources for the rest of the network.
Resilience – ring network

Resilience with a ring network, where a microwave hop is used to close a fiber ring, in case laying the fiber is difficult or too expensive.

There are also more specific types of microwave-related resiliency characteristics that will help make the link more robust:

  • Adaptive modulation
    Traditional static modulation was an on/off type – it worked or it didn’t. Adaptive modulation will deliver all possible capacity at all times. This means more capacity when things are going well, but more importantly, continuous connectivity even when traditional solutions no longer work. Misaligned antennas can reduce system gain below the intended availability objective, but you may still have some connectivity left with adaptive modulation. Adaptive modulation will increase the robustness of the link.
  • radio link
    When multiple links are available, all capacity is consolidated into a single common resource. Based on QoS settings, high priority traffic takes priority regardless of available capacity. Therefore, a modern 2+0 link with adaptive modulation and radio link can be much more resilient than a traditional 1+1 link has ever been.
  • Energy saving depending on traffic
    When there is a big network problem, it is not uncommon for it to also be a power problem and the backup battery needs to work as long as possible. This is where TAPS helps – power consumption depends on traffic needs instead of using the same power all the time. This can reduce the power used and extend battery backup time, increasing the chance that power will return in time to charge the batteries.
  • Emergency release
    Modern products are most often based on software licenses that define their capacity and capabilities. In a network scenario with a fire in some sites and a loss of connections in other sites, it may be necessary to use what is left to the maximum. That’s when the Emergency Unlock feature comes in. All features and abilities are unlocked with a single command for a limited time until the issue is fixed for good.
  • Remote management
    When network reorganization is needed due to an emergency, you don’t want to schedule a series of site visits. Therefore, it is essential to have a safe and secure DCN connection over which all changes can be made.
Mission essential firefighters and fire truck

The good news is that modern microwave equipment supports all of the requirements mentioned above!

The bad news is that they also seem to be needed! Now more than ever.

You want to know more ?

Microwaves – MINI-LINK 6000, microwave family for economical mobile transport networks

Long distance microwave

American Samoa connected via a long microwave backhaul link

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