Point of Presence (POP)

Definition of Point of Presence (POP) in Network Encyclopedia.

What is Point of Presence (POP)?

POP, stands for Point Of Presence, is the local access point for an Internet service provider (ISP). A point of presence (POP) consists of the high-speed telecommunications equipment and technologies that enable users to connect to the Internet via their ISP. The POP might include call aggregators, modem banks, routers, and high-speed Asynchronous Transfer Mode (ATM) switches.

A POP has one or more unique IP addresses plus a pool of assignable IP addresses for its permanent and dial-up clients. The actual POP for an ISP might be located within the telecommunications facility of a telco or a long-distance carrier. The ISP rents or leases space in the facility to install the routers and access servers that provide Internet connectivity for clients and for the equipment that provides the ISP with a high-speed T1 or T3 connection to the Internet’s backbone.

POP examples
POP examples

A point of presence (POP) is a location within a LATA that has been designated by an access customer for the connection of its facilities with those of a LEC. Typically, a POP is a location that houses an access customer’s switching system or facility node. Consider an «access customer» as an interexchange carrier, such as Sprint or AT&T.

At each POP, the access customer is required to designate a physical point of termination(POT) consistent with technical and operational characteristics specified by the LEC. The POT provides a clear demarcation between the LEC’s exchange access functions and the access customer’s interexchange functions. The POT generally is a distribution frame or other item of equipment (a cross-connect) at which the LEC’saccess facilities terminate and where cross-connection, testing, and service verification can occur. A later federal court judgment (1992) required a LEC to provide space for equipment for CAPs (competitive access providers).

In other words, Points of Presence are the locations from which network services are provided.

PoPs may be shared by several service providers

If a carrier does not have a local point of presence from which corporate customers can access the service, the carrier can route the traffic to the nearest PoP at little or no cost to the customer if the traffic volume makes the backhaul arrangement worthwhile. For consumers, the back-haul arrangement might be in the form of toll-free 800-number access to the nearest PoP.

The NAPs on the major Internet backbones, for example, are equipped to handle large amounts of traffic to avoid bottlenecks on the Internet. The largest NAP, located in Chicago, is operated by Ameritech Advanced Data Services (AADS). The NAP has more than 40 companies, Internet service providers and universities connected to it via DS3 (45 Mbps), OC-3c (155 Mbps), and OC-12 (622 Mbps) Asynchronous Transfer Mode (ATM) connections.


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