Demarcation point
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In telephony, the demarcation point is the point at which the public switched telephone network ends and connects with the customer's on-premises wiring. It is the dividing line which determines who is responsible for installation and maintenance of wiring and equipment—customer/subscriber, or telephone company/provider. The demarcation point varies between countries and has changed over time.
Demarcation point is sometimes abbreviated as demarc, DMARC, or similar. The term MPOE (minimum or main point of entry) is synonymous, with the added implication that it occurs as soon as possible upon entering the customer premises. A network interface device often serves as the demarcation point.
History
Prior to Federal Communications Commission (FCC) regulations separating the ownership of customer premises telecommunication equipment from the telephone network, there was no need for a public standard governing the interconnection of customer premises equipment (CPE) to the United States' telephone network, since both the devices and the “local loop” wiring to the central office were owned and maintained by the local telephone company. Concurrent with the transfer of existing "embedded" CPE to the customer (customers could buy new telephones at retail or could continue to lease their existing equipment from the company), it was necessary to provide a standardized way to connect equipment, and also provide a way to test the phone company's service separately from the customer's equipment.
The ability of customers to buy and maintain their CPE and attach it to the network was stimulated by lawsuits by equipment manufacturers, such as the
The newly developed equipment-network separation was codified in Part 68 of the Code of Federal Regulations in the United States and later in comparable regulatory standards in other countries.
The physical and electrical interconnection is called the demarcation point, or Demarc, which includes one or more customer-accessible jack interfaces; previously, the interface was typically hard-wired and often in a telephone company-owned locked enclosure.
The premises-vs.-network separation in the United States, insofar as it affected the former
Equipment
Canada
The demarcation point varies from building type and service level. In its simplest form, the demarcation point is a
United States
In the United States, the modern demarcation point is a device defined by
The modern demarcation point is the network interface device (NID) or intelligent network interface device (INID) also known as a "smartjack".[2] The NID is the telco's property. The NID may be outdoors (typically, mounted on the building exterior in a weatherproof box) or indoors.
The NID is usually placed for easy access by a technician. It also contains a lightning arrestor,
When the loop is disconnected, the on-premises wiring is isolated from the telephone network and the customer may directly connect a telephone to the network via the jack to assist in determining the location of a wiring fault. In most cases, everything from the central office to and including the demarcation point is owned by the carrier and everything past it is owned by the property owner.
As the local loop becomes upgraded, with
Demarcation points on houses built prior to the
DEMARCs that handle both telephony and IT fiber optic internet lines often do not look like the ones pictured above. In many places several customers share one central DEMARC for a commercial or strip mall setting. Usually a DEMARC will be located indoors if it is serving more than a single customer. This may impede access. Outdoor ones provide easier access, without disturbing other tenants, but call for weatherproofing and punching through a wall for each new addition of wires and service.
Typically indoor DEMARC's will be easily identified by a
Demarcation point extension
A demarcation point extension, or demarc extension is the transmission path originating from the interface of the access provider's side of a demarcation point within a premises and ending at the termination point prior to the interface of the edge Customer Premises Equipment (CPE). This may include in-segment equipment, media converters and patch cords as required to complete the circuit's transmission path to the edge CPE. A demarc extension is more correctly termed "Service Interface Extension", and may also be referred to as inside wiring, extended demarc, circuit extension, CPE cabling, riser cabling or DMARC extension.[3]
A demarc extension became an important factor to consider in a building's telecommunications infrastructure after the 1984
United Kingdom
In the United Kingdom, the demarcation point occurs on the LJU master socket, whose wiring is partly owned by the customer, partly owned by the phone company. Other secondary sockets are the customer's property. Newer NTE-5 master phone sockets have a removable front panel: the front panel and its wiring is the customer's, while the rear wiring is Openreach's.
The removable panel allows separation of these two parts and independent maintenance, and access to a test socket to determine whether line faults are in the customer's wiring or Openreach's (formerly BT's) external network.
See also
References
- ^ "Administrative Council for Terminal Attachments". Part68.org. Retrieved 2016-04-28.
- ^ "Demarc Extension Services Nationwide T1 Circuit Extensions". Integratednetworkcable.com. Retrieved 2016-04-28.
- ^ "Demarc Extension Services Nationwide T1 Circuit Extensions". Integratednetworkcable.com. Retrieved 2016-04-28.