Core network
Encyclopedia
A core network, or network core, is the central part of a telecommunication network that provides various services to customers who are connected by the access network
. One of the main functions is to route telephone calls
across the PSTN.
Typically the term refers to the high capacity communication facilities that connect primary nodes. Core/backbone network
provides paths for the exchange of information between different sub-networks. For enterprise networks serving one organization, the term backbone is more used, while for service provider
s, the term core network is more used.
In the U.S. local exchange
Core Networks are linked by several competing Interexchange network
s; in the rest of the world the Core Network has been extended to national boundaries.
Core/backbone network usually has a mesh topology that provides any-to-any connections among devices on the network. Many main service providers would have their own core/backbone networks, that are interconnected. Some large enterprises have their own core/backbone network, which are typically connected to the public networks.
The devices and facilities in the core / backbone networks are switches and routers. The trend is to push the intelligence and decision making into access and edge device
s and keep the core devices dumb and fast. As a result, switches are more and more often used in the core/backbone network facilities. Technologies used in the core and backbone facilities are data link layer
and network layer
technologies such as SONET
, DWDM, ATM, IP, etc. For enterprise backbone network, gigabit Ethernet
or 10 gigabit Ethernet technologies are also often used.
Physically, one or more of these logical functionalities may simultaneously exist in a given core network node.
.
There exist basically two Core Network types:
Both variants have evolved over time to integrate new services and air interface
s.
Access network
An access network is that part of a telecommunications network which connects subscribers to their immediate service provider. It is contrasted with the core network, which connects local providers to each other...
. One of the main functions is to route telephone calls
Routing in the PSTN
Routing in the PSTN is the process used to route telephone calls across the public switched telephone network. This process is the same whether the call is made between two phones in the same locality, or across two different continents....
across the PSTN.
Typically the term refers to the high capacity communication facilities that connect primary nodes. Core/backbone network
Backbone network
A backbone network or network backbone is a part of computer network infrastructure that interconnects various pieces of network, providing a path for the exchange of information between different LANs or subnetworks. A backbone can tie together diverse networks in the same building, in different...
provides paths for the exchange of information between different sub-networks. For enterprise networks serving one organization, the term backbone is more used, while for service provider
Service provider
A service provider is an entity that provides services to other entities. Usually, this refers to a business that provides subscription or web service to other businesses or individuals. Examples of these services include Internet access, Mobile phone operators, and web application hosting...
s, the term core network is more used.
In the U.S. local exchange
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
Core Networks are linked by several competing Interexchange network
Interexchange carrier
An Interexchange Carrier is a U.S. legal and regulatory term for a telecommunications company, commonly called a long-distance telephone company, such as MCI , Sprint and the former AT&T in the United States...
s; in the rest of the world the Core Network has been extended to national boundaries.
Core/backbone network usually has a mesh topology that provides any-to-any connections among devices on the network. Many main service providers would have their own core/backbone networks, that are interconnected. Some large enterprises have their own core/backbone network, which are typically connected to the public networks.
The devices and facilities in the core / backbone networks are switches and routers. The trend is to push the intelligence and decision making into access and edge device
Edge device
Edge devices are routers, routing switches, integrated access devices , multiplexers, and a variety of metropolitan area network and wide area network access devices that provide entry points into enterprise or service provider core networks...
s and keep the core devices dumb and fast. As a result, switches are more and more often used in the core/backbone network facilities. Technologies used in the core and backbone facilities are data link layer
Data link layer
The data link layer is layer 2 of the seven-layer OSI model of computer networking. It corresponds to, or is part of the link layer of the TCP/IP reference model....
and network layer
Network layer
The network layer is layer 3 of the seven-layer OSI model of computer networking.The network layer is responsible for packet forwarding including routing through intermediate routers, whereas the data link layer is responsible for media access control, flow control and error checking.The network...
technologies such as SONET
Sonet
Sonet may refer to:* Sonet Records, European record label* Synchronous optical networking * Saab Sonett...
, DWDM, ATM, IP, etc. For enterprise backbone network, gigabit Ethernet
Gigabit Ethernet
Gigabit Ethernet is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second , as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks where it performed...
or 10 gigabit Ethernet technologies are also often used.
Primary functions
Core networks typically providing the following functionality:- Aggregation: The highest level of aggregation in a service provider network. The next level in the hierarchy under the core nodes is the distribution networks and then the edge networks. Customer Premise Equipment (CPE) do not normally connect to the core networks of a large service provider.
- AuthenticationAuthenticationAuthentication is the act of confirming the truth of an attribute of a datum or entity...
: The function to decide whether the user requesting a service from the telecom network is authorized to do so within this network or not. - Call Control/Switching: Call controlCall controlIn telephony, call control refers to the software within a telephone switch that supplies its central function. Call control decodes addressing information and routes telephone calls from one end point to another. It also creates the features that can be used to adapt standard switch operation to...
or switchingTelephone exchangeIn the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
functionality decides the future course of call based on the call signalling processing. E.g. switching functionality may decide based on the "called numberCalled partyThe called party is a person who answers a telephone call. The person who initiates a telephone call is the calling party....
" that the call be routed towards a subscriber within this operator's network or with Number Portability more prevalent to another operator's network. - Charging: This functionality handles the collation and processing of charging data generated by various network nodes. Two common types of charging mechanisms found in present day networks are prepaid charging and postpaid charging. See Automatic Message AccountingAutomatic Message AccountingAutomatic message accounting provides detail billing for telephone calls. When direct distance dialing was introduced in the US, message registers no longer sufficed for dialed telephone calls...
- Service Invocation: Core network performs the task of service invocation for its subscribers. Service invocation may happen based on some explicit action (e.g. call transferCall transferA call transfer is a telecommunications mechanism that enables a user to relocate an existing call to another phone or attendant console by using the transfer button and dialing the required location. The transferred call is either announced or unannounced....
) by user or implicitly (call waitingCall waitingCall waiting , in telephony, is a feature on some telephone networks. If a calling party places a call to a called party which is otherwise engaged, and the called party has the call waiting feature enabled, the called party is able to suspend the current telephone call and switch to the new...
). Its important to note however that service "execution" may or may not be a core network functionality as third party network/nodes may take part in actual service execution. - GatewayGateway (telecommunications)In telecommunications, the term gateway has the following meaning:*In a communications network, a network node equipped for interfacing with another network that uses different protocols....
s: Gateways shall be present in the core network to access other networks. Gateway functionality is dependent on the type of network it interfaces with.
Physically, one or more of these logical functionalities may simultaneously exist in a given core network node.
Other functions
Besides above mentioned functionalities, the following also form part of a core network:- O&M: Operations & Maintenance centre or Operations Support Systems to configure and provision the core network nodes. Number of subscribers, peak hour call rate, nature of services, geographical preferences are some of the factors which impact the configuration. Network statistics collection, alarm monitoring and logging of various network nodes actions also happens in the O&M centre. These stats, alarms and traces form important tools for a network operator to monitor the network health and performance and improvise on the same.
- Subscriber Database: Core network also hosts the subscribers database (e.g. HLR in GSM systems). Subscriber database is accessed by core network nodes for functions like authentication, service invocation etc.
Mobile
A core network is the basic part of a mobile communications network that provides various services to customers who are connected by the access networkAccess network
An access network is that part of a telecommunications network which connects subscribers to their immediate service provider. It is contrasted with the core network, which connects local providers to each other...
.
There exist basically two Core Network types:
- The Mobile Application PartMobile Application PartThe Mobile Application Part is an SS7 protocol which provides an application layer for the various nodes in GSM and UMTS mobile core networks and GPRS core networks to communicate with each other in order to provide services to mobile phone users...
(MAP) used for GSM and UMTS - The IS-41IS-41IS-41, also known as ANSI-41, is a mobile, cellular telecommunications system standard to support mobility management by enabling the networking of switches. ANSI-41 is the standard now approved for use as the network-side companion to the wireless-side AMPS , IS-136 , cdmaOne, and CDMA2000 networks...
core network used for D-AMPS (TDMA), cdmaOne and CDMA2000CDMA2000CDMA2000 is a family of 3G mobile technology standards, which use CDMA channel access, to send voice, data, and signaling data between mobile phones and cell sites. The set of standards includes: CDMA2000 1X, CDMA2000 EV-DO Rev. 0, CDMA2000 EV-DO Rev. A, and CDMA2000 EV-DO Rev. B...
.
Both variants have evolved over time to integrate new services and air interface
Air interface
In mobile or wireless communication, the air interface is the radio-based communication link between the mobile station and the active base station...
s.