PNM and Associated Standards
By Chris Bastian
Network architectures and operations have become more complex in the past few decades. When I began working in telecommunications in the mid-1980s, telecom networks were still using circuit switches such as the 5ESS and DMS-100, while data networks were primarily using the X.25 packet switch standard. With these legacy network elements and protocols, the maintenance support model was reactive, or break-fix. Alarms would come into the network operations center, and technicians would be dispatched to repair the outage.
Fast forward to today, when multiple purpose-built networks have converged into a single network supporting multiple services — including voice, video, data, and business services — each with varying service performance demands for speed, latency and other network characteristics.
A more proactive maintenance model has evolved in concert with these more complex networks. Initially focused on DOCSIS, proactive network maintenance was developed by CableLabs beginning in 2008. In the past couple years, PNM capabilities have expanded beyond DOCSIS and have started to focus as well on Wi-Fi, optical, and MoCA.
The CableLabs PNM working group (WG) is creating a common PNM architecture, specifications and reference designs, as requested by their members. Examples of these documents are:
- Combined Common Collection Framework Architecture Technical Report
- The common collection framework is a set of Python software modules that handles the task of collecting PNM data from the network elements and presenting the data to PNM applications. It provides the data in a common form so that software applications don’t have to talk network language to get the data it needs. It also protects the network from overly frequent data requests. (Jason Rupe/CableLabs, November 7, 2017)
- Wi-Fi PNM Common Collection Framework Technical Report
- PNM Best Practices: HFC Networks
CableLabs and SCTE•ISBE work very closely together to transfer CableLabs specifications from a CableLabs WG to an SCTE•ISBE Standards WG at the appropriate time. SCTE•ISBE through its working groups converts the CableLabs documentation into ANSI-accredited standards. The timing of this transfer depends largely on when:
- The CableLabs specification is deemed to be stable;
- The specification is seeing a low rate of engineering change requests (ECRs) or is formally CLOSED to ECRs; and,
- The specification meets the cable industry’s technical needs that are not already being met by another standard.
The SCTE PNM working group charter is: “to provide operational practices, guidelines, and training in collaboration with industry partners’ PNM initiatives. The scope of PNM includes HFC, MoCA, Wi-Fi and optical access networking technologies. The efforts of this working group are focused on standardizing and expediting new PNM technology to operations and in the field.”
Examples of recent SCTE PNM Working Group documentation includes:
- DOCSIS 3.1 PNM test verification via signal analysis
- A PNM training material refresh focused on these eight upstream measurements:
- Capture of active and quiet probes;
- Triggered spectrum analysis;
- Impulse noise statistics;
- Equalizer coefficients;
- Forward error correction (FEC) statistics;
- Histogram;
- Channel power; and
- Receive modulation error ratio (RxMER) per subcarrier.
Proactive network maintenance continues to evolve, in concert with the underlying access network technologies of DOCSIS, optical, Wi-Fi and MoCA. PNM specifications and standards are essential to staying in sync with these technologies, in order to:
- Ensure network interoperability;
- Speed up introduction of innovative PNM products to market;
- Lower cost by eliminating redundancy and minimizing errors;
- Simplify how to understand and compare competing PNM products; and
- Enable compliance with relevant regulations.
SCTE•ISBE Cable Tec Expo® 2018 featured several papers and presentations on PNM. These can be downloaded at https://www.onlineevent.com/scte-isbe/events/1309. Hold the dates for this year’s Expo—Sept. 30th–Oct. 3rd, in New Orleans – when PNM again will be on the agenda.
I am excited that much of this issue of Broadband Library is dedicated to proactive network maintenance. Enjoy the rest of the magazine.
Chris Bastian
SVP and CTO, SCTE•ISBE
Chris Bastian is responsible for ensuring that SCTE and ISBE maintain a leadership role in standardizing and operationalizing advanced technology, including the SCTE Standards Program and the SCTE Engineering Committee — as well as groundbreaking efforts such as SCTE’s Energy 2020 program. Prior to joining SCTE•ISBE, Chris spent 15 years with Comcast, ultimately becoming executive director of Comcast’s Xfinity Wi-Fi network. Previously, he also had worked with RCN and the National Security Agency. Chris and his family love camping, biking, hiking and other outdoor activities. The family vacation in 2015 was to Alaska, where they hiked in Denali National Park. In the summer of 2014, Chris and his son Ben hiked 120 miles at Philmont Scout Ranch in New Mexico. Highlights were hiking to the top of Mount Baldy (elev. 12,441 feet) and the Tooth of Time to catch the sunrise.
