Editing Cable modem termination system (section)

==Architectures==
A CMTS can be broken down into several different architectures, Integrated CMTS (I-CMTS), Modular (M-CMTS), Virtual CMTS (vCMTS) and remote CMTS. An I-CMTS incorporates into a single unit all components necessary for its operation.<ref>{{cite book | url=https://books.google.com/books?id=zUmxDwAAQBAJ&dq=integrated+cmts&pg=PA37 | isbn=978-0-470-16372-6 | title=Next Generation IPTV Services and Technologies | date=2 January 2008 | publisher=John Wiley & Sons }}</ref> There are both pros and cons to each type of architecture.

===Modular CMTS (M-CMTS)===
In a M-CMTS solution the architecture of an I-CMTS is broken up into two components. The first part is the Physical Downstream component (PHY) which is known as the Edge QAM (EQAM).  The second part is the IP networking and [[DOCSIS]] MAC Component which is referred to as the M-CMTS Core.  There are also several new protocols and components introduced with this type of architecture.  One is the DOCSIS Timing Interface, which provides a reference frequency between the EQAM and M-CMTS Core via a DTI Server.  The second is the Downstream External PHY Interface (DEPI).  The DEPI protocol controls the delivery of DOCSIS
frames from the M-CMTS Core to the EQAM devices <ref name="cablelabmcmts">{{cite web|title=Data-Over-Cable Service Interface Specifications Modular Headend Architecture|url=http://www.cablelabs.com/wp-content/uploads/specdocs/CM-SP-M-OSSI-I08-081209.pdf|website=www.cablelabs.com|access-date=2015-02-27|archive-url=https://web.archive.org/web/20150227192938/http://www.cablelabs.com/wp-content/uploads/specdocs/CM-SP-M-OSSI-I08-081209.pdf|archive-date=2015-02-27|url-status=dead}}</ref>  Some of the challenges that entail an M-CMTS platform are increased complexity in RF combining and an increase in the number of failure points.  One of the benefits of an M-CMTS architecture is that it is extremely scalable to larger numbers of downstream channels.<ref name="cmtsarchitecture">{{cite web|title=CMTS Architectures|url=http://volpefirm.com/docsis3_architecture/|website=volpefirm.com}}</ref>

===Virtual CMTS===
Virtual CCAPs (vCCAPs) or virtual CMTSs (vCMTSs) are implemented on commercial off the shelf x86-based servers with specialized software,<ref>{{Cite web|url=https://www.lightreading.com/cable-technology/harmonic-s-cableos-now-connected-to-18-4m-modems|title=Harmonic's 'CableOS' now connected to 18.4M modems|website=www.lightreading.com}}</ref>  and can be used to increase service capacity without purchasing new CMTS/CCAP chassis, or add features to the CMTS/CCAP more quickly.<ref>{{cite web |title=Lessons from Operating Tens of Thousands of Remote PHY Devices |url=https://www.nctatechnicalpapers.com/Paper/2021/2021-lessons-from-operating-tens-of-thousands-of-remote-phy-devices/download |publisher=SCTE |access-date=2 March 2024}}</ref>

===Remote CMTS===
Remote CMTS/Remote CCAP moves all CMTS/CCAP functionality to the outside plant, in stark contrast to conventional CMTSs or CCAPs which are installed at a service provider location.<ref name="auto1">{{cite web |title=Impact of CCAP to CM Distance in a Remote PHY Architecture |url=http://bowe.id.au/michael/isp/DOCSIS/collected-references/2015-impact-of-ccap-to-cm-distance-in-a-remote-phy-architecture%20(1).pdf |access-date=2 March 2024}}</ref><ref name="auto4">{{cite web |last1=Chapman |first1=John |title=DOCSIS Remote PHY Modular Headend Architecture (MHA v2) |url=https://www.cisco.com/c/dam/en/us/solutions/ns341/ns522/ns791/workshop_remote_phy_chapman_paper.pdf |publisher=SCTE |access-date=2 March 2024}}</ref>