When the Going Gets Tough…

Today’s DWDM optical networks span the globe and carry colossal amounts of data, underpinning our hyper-connected, internet-based society. Pushing the boundaries of optical networking technology is a daily challenge for the whole industry. We often see this most clearly in subsea or long-haul networks, with records being broken for the longest reach at, say, 800G or the highest capacity per fiber pair across the Atlantic. But innovation is also taking place at the opposite end of the DWDM network, pushing higher-capacity optical transport toward the edge and deeper into access networks, closer to the end user.

The challenges in these edge environments are very different than those in long-haul and subsea networks. At the edge, we generally aren’t focused on achieving the highest spectral efficiency. Instead, the focus is on driving higher capacity into smaller footprints and with less power and improved economics in tough operational environments. Tough is of course a relative term. We aren’t talking about access networks within toxic industrial waste pools or on the surface of the moon (well, not yet anyway), but we are talking about deploying networking hardware outside of environmentally controlled locations (think huts, data centers, or central offices), typical in telecoms networks.

The Key Factors of Hardened Networking

Many people initially associate hardening with the ability to support a broader temperature range than is found in the local exchange environment, which is usually air conditioned and heated to ensure that the operating temperature stays within acceptable limits. However, hardened DWDM access networks require a broader range of additional requirements to support a wider set of challenges involved in supporting the range of possible installation locations.

Street cabinets and similar enclosures in locations such as cell sites are the most common deployment locations within these types of networks, but other locations include non-controlled equipment rooms in customer premises. Sometimes smaller passive/unpowered locations also include wall- or pole-mounted units or even subterranean locations such as enclosures under manhole covers.

Operators of hardened DWDM network locations need to consider the following additional requirements beyond those found in the rest of the DWDM network:

1. Extended temperature range of -40° to +65°C (-40° to +149°F) for non-telco environments (a useful bit of pub quiz trivia there is that -40°C is equal to -40°F!)
2. Small footprint, as space is typically a scare commodity in street cabinets and other hardened locations
3. Low power consumption as these sites are normally power-limited too
4. Low acoustic noise to avoid upsetting the neighbors
5. Ease of use for ease of installation and servicing by field engineers trained to deal with a broad range of technologies rather than DWDM specialists
6. All front access as that is all that site engineers will be able to access
7. Specialized application-specific features such as the low latency, timing/synchronization, or higher resilience to vibration required to support various high-performance access applications

Hardened Network Applications and Architectures

Hardened DWDM networks support a variety of networking applications. The most obvious applications for hardened DWDM networks are those that now require DWDM levels of bandwidth in access networks close to the end user and beyond the reach of standard telco exchange buildings, such as:

• Residential broadband networks – PON, DSL, or cable networks requiring DWDM-based backhaul within the access infrastructure
• Mobile transport networks – 5G xHaul or 4G backhaul to high-capacity fiber-connected cell sites
• Business services – Driving hardened devices at the customer premise or within the aggregation network
• Converged networks supporting all three of these applications

However, there are also various additional applications for hardened DWDM networks that might not immediately be so obvious:

• Utility and transport networks – Many utility operator networks, such as those supporting the oil and gas or electrical power industries, and transport networks, such as railway or highway networks, can also benefit from hardened DWDM transport. These networks differ slightly from metro access networks in that they may span longer distances, such as along oil or gas pipelines or along railway lines or major highways.
• In-line amplifier (ILA) nodes in high-capacity long-haul networks in tough environments – Long-haul DWDM networks can sometimes span rugged environments where there is limited existing infrastructure, such as deserts or rural/mountainous areas between major cities in large countr In these applications, hardened DWDM devices can be used for in-line amplifier sites to reduce the need for environmentally controlled buildings or to lower the cooling requirements within existing locations that could be used as ILA sites.
• Removing/lowering air-conditioning requirements in space- and power-constrained environments – In a similar manner to the previous application, migration to hardened devices can also be used in locations that are space and/or power restricted to remove or lower the need for air conditioning within the site. This lowers operational costs and frees up space and power for additional networking hardware.
• Off-grid (power) locations – A further adaptation of the previous two applications is utilizing hardened DWDM in very remote locations, such as very remote ILA sites for long-haul networks, that are even off the power grid. In these cases, hardened DWDM equipment removes the need for additional air conditioning, and the whole site can be powered by solar power with a battery backup.
• Site consolidation activities – Many network operators are consolidating access sites to lower operational costs. Hardened DWDM enables these network operators to transfer networking resources to street cabinets and decommission temperature-controlled buildings.

The Benefits of Toughing It Out

Going back to the title of this blog, I’ll admit that Billy Ocean probably didn’t have hardened DWDM networks in mind when he wrote his 1985 smash hit, “When the Going Gets Tough, the Tough Get Going.” But for those of us in the optical networking industry, especially those dealing with access and metro networks, pushing the boundaries of DWDM into tough environments is a real challenge. It’s one that Infinera has embraced, and we’ve innovated to push DWDM, and even coherent 100G/200G DWDM, deep into these tough environments.

These networks enable network operators to push the higher capacity they need closer to the edge of the network and closer to the end customer. These capabilities can also address the CapEx and OpEx challenges associated with space, power, and cooling within DWDM networks either at the edge or in challenging locations in long-haul networks.

If you are interested in learning more about these challenges, the solutions that we’re deploying to address them, and the benefits this is bringing to network operators, then check out our new Hardened DWDM for Demanding Transport Network Applications application note.