Trilliant’s SecureMesh: Great Interoperability, but Can It Scale?

Trilliant’s communications technology has garnered attention recently, both because of its selection in several utility contracts and because it closed a large round of investment.  This article evaluates Trilliant’s SecureMesh, an AMI smart-grid enabling communications technology. 

 

SecureMesh gives device vendors a standards-based way to rapidly deploy mesh technology in dense urban smart grid applications.  Trilliant is one of the first AMI communications vendors to use a commodity IEEE 802.15.4 PHY and MAC layer for mesh purposes.

 

To understand my evaluation, you need to grasp three essential elements:

• The role of the SGN Scorecard
• The purpose of mesh networks in a Smart Grid
• How Trilliant measures up

The Role and Importance of the SGN Scorecard

The SGN Scorecard was developed for a very important reason: most of today's products do not adhere to Smart Grid principles. They do not support the requirements envisioned by Smart Grid researchers such as EPRI, the California Energy Commission's Public Interest Energy Research program, the Modern Grid Initiative and DOE's GridWise program. Nor do they adhere to the mandates in the Energy Independence and Security Act of 2007.

 

In particular, several elements of the EPRI IntelliGrid Architecture are critical to implementing a Smart Grid:

• Proven, Internet derived communication technologies
• Service based architecture at the enterprise level
• Self healing technology
• Well defined interfaces and points of interoperability
• Application of industry and international standards
• Built in security and network management

 

The SGN Scorecard is a checklist that measures whether products meet minimum standards for a Smart Grid. We will use it as the benchmark for all Tech Talk reviews. You are invited to use it free of charge for your own evaluations. For a further explanation and a blank version you can copy freely, download the PDF version of the Scorecard. (See link below.)

 

The Purpose of Mesh Networks in a Smart Grid

One of the key business justifications for the Smart Grid is labor savings – the automation of crew-served tasks.  Communications technologies are key to getting information to grid controllers and automation for billing, decision-making, and service dispatch.  Communications networks enable distribution automation, feeder reconfiguration, remote cap bank control, meter reading, and demand response.

 

For this reason, the network’s reach, reliability, security, capacity, and latency (delay) are key factors in understanding what Smart Grid applications it can support.

 

Network reach tells us where we can install grid sensors and effectors.  We want to maximize network coverage per endpoint investment.  Mesh networks installed in sufficient density (and with sufficient collection points) have the potential to be extremely reliable. Mesh networks extend reach by routing around physical obstacles which might block tower-based systems.

 

Reliability tells us what operational risk we are accepting in deploying a network. If we have a Smart Grid application concept, but can’t count on being able to control or monitor it whenever we want, the investment is lost.  Mesh networks deliver reliability through shared purpose. It is each node’s job to forward packets to the collection points. If one node fails, others can be used as a route to the collection point.

 

Security tells us what risk a utility would be accepting in terms of ratepayers’ privacy and comfort.  Mesh networks sometimes struggle with security, since they inherently rely on neighboring nodes to forward packets.  This design attracts Man in the Middle attacks. Good mesh networks preserve application layer security independently and then layer in link security in as well.  Mesh networks require secured firmware distribution means and secured time sources for the same reason.  Meshes generally detract from delay.

 

Network capacity tells us which applications we can take across the mesh.  Applications such as demand response are bandwidth limited.  Mesh routing offers the potential for high bandwidth in theory. In practice, it is often link limited and variable between different implementations.

 

Network delay tells us more about which applications we can carry over the mesh.  Delays on the order of multiples of seconds are bad for some applications. Other applications can tolerate hours. Each passage through a mesh node adds measureable latency to that packet’s propagation.  Adding more collection points can often alleviate latency issues.

 

How SecureMesh Measures Up

Scalability. Initial field testing with one utility has shown that Trilliant’s average node separation does not compare in range to many other AMI communications vendor’s offerings. Therefore, more communications gateways and WAN backhauls would probably be required. As a result, Trilliant’s mesh design seems best for dense urban or dense residential deployment. This may limit its effective use in rural electric areas.  However, Trilliant’s large scale implementation at Hydro One clearly shows that this architecture can be applied to achieve the desired results.
 
The selection of a 2.4 GHz IEEE 802.15.4 radio at the marketed transmit power of 100 mW has comparable free-space propagation to other vendor claims. However, 2.4 GHz is not only in the crowded ISM bands, it propagates with significantly reduced range, both due to under-glass antenna and significant non line of sight path (foliage being particularly bad). Low-power 2.4 GHz requires greater path diversity. Protocols implemented over IEEE 802.15.4 achieve this by limiting interference due to transmit power and installing more nodes, close together.  Trilliant overcomes some of these issues by utilizing 1 Watt radios in all but urban environments where the 100 mW radio is employed.
 
It is worth noting that the alternative radio band used by many competitors – the 900 MHz band - is filled with devices that were made in the 80’s and 90’s, including cordless phones, baby monitors, etc.  Most of these were made with narrowband technology, which is very sensitive to interference.  900 MHz cordless phones have a severe impact on narrowband radio communications.  In comparison, the IEEE 802.15.4 standard was specifically designed to co-exist with Wi-Fi and other systems. The DSSS technology allows these systems to co-exist without the severe impact of interference that you’d see with narrowband 900 MHz solutions.
 
A communications network is part of a larger business operating system and a utility Smart Grid architecture. Enterprise integration / scalability appears to be an issue for Trilliant. We expected to see scalability potential to the largest utility’s network monitoring, maintenance, and enterprise integration. Although Trilliant’s Unity Application Suite uses industry standard SOAP interfaces, the lack of an advertised enterprise architecture integration path may mean that Trilliant works best with small or medium utilities willing to perform integration for any legacy or bolt-on systems. One place Trilliant makes up for this is with a broad HAN and WAN device integration offering.
 
Our final scalability concern is operational scalability and a clear lack of advertised network management and detailed test tools. To our knowledge, there is no well-defined specification for SNMP usage on an 802.15.4 mesh network.  Trilliant does not describe how they intend to manage large numbers of field devices in a scalable fashion.
 
In the proper install density, Trilliant has the potential to be extremely reliable due to its mesh configuration. Limiting factors may include under the glass RF antenna. Trilliant also wins points for giving the utility the ability to select from a wide range of WAN technologies.
 
Security. Trilliant appears to enable application security around C12-19 group security. Access control groups are leveraged and enforced during C12-22 interactions with an underlying meter. Less attention seems to be given to an integrated, comprehensive security architecture.
 
Network capacity is very well defined by the 802.15.4 PHY layer standard with a physical layer bit rate of 250 kb/s. One non-obvious fact occurs if an application bottleneck occurs in the mesh. This is not an issue for bubble-up meter data in most cases. Application congestion will be more obvious should cross-grid devices such as DA devices interact cross-mesh on the network.  All mesh network solutions have this limitation however and Trilliant’s 250 kb/s bandwidth is 2.5 times faster than many other solutions and therefore should perform better than most in cross-grid applications.
 
Network delay will not be an issue for all applications; one application of concern could potentially be firmware updates, depending on how they are implemented.

 

Metric	Score (10 is best)	Comments
Impact	8	Impact is significant. Early AMI deployments are using this communications technology today.
Openness	9	Openness in communications components, protocols, and device integration architecture means SecureMesh interoperates with many and varied device vendors.
Standardization	7	Trilliant SecureMesh advertises use of 3 specific standards: IEEE 802.15.4, ANSI C12-19, ANSI C12-22. It enables WAN component integration of many standard WAN technologies spannig from Cell, WiFi, Wired, and WiMax.
Security	6	Trilliant focuses on application-centered security and authorization control, but appears that it could be weaker on security assurance mechanisms, node security, and  link security than its contemporaries.
Manageability	5	Trilliant lacks strong network management and insight tools, key to managing larger or deeper smart grid deployments.
Upgradeability	6	The lack of strong network management tools and security assurance mechanisms makes remote upgrade in a scalable fashion problematic in its present form.
Scalability	6	Trilliant offers many ways to connect communications devices, but lacks a strong roadmap for enterprise integration with emerging utility enterprise systems..
Extensibility	9	Trilliant focuses on device vendor integration. This is most evident by their early integrated offering of wide area and home area network oriented devices.
Self-Healing	9	Meshes based on IEEE 802.15.4 rely on path-diversity for resilience. This implies that dense deployments will form highly resilient communications fabrics if deployed with the proper radio power and density.
Interactivity	9	Among other things, Trilliant has integrated with popular customer-interactive HAN and DR vendors such as EnerGate PCTs, EnTek load controls, and Aztech IHDs.
Summary	74 Total	100 Possible

 

Conclusion

We like the fact that so many HAN and WAN devices interact with this vendor’s product. We are a bit concerned about the scalability to every utility’s needs.  We’d like to see this vendor offer a mature enterprise integration model.  We’d also like to see more support built in for those utilities working to evaluate this technology, including network management and network monitoring tools. 

 

Research Credit:  Brad Singletary - brad@enernex.com

 

   Email Erich W. Gunther

   Smart Grid Scorecard (PDF) 

   EPRI IntelliGrid Architecture Web site

   GridWise Architecture Council

   Trilliant Web site

   VentureBeat article on Trilliant’s $40M venture funding