Core network

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Please improve this article if you can. (June 2007)

A core network (or network core) is the central part of a telecom network that provides various services to customers who are connected by the access network.

[edit] Primary Functions

Core networks typically providing the following functionality:

  1. 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.
  2. Authentication: The function to decide whether the user requesting a service from the telecom network is authorized to do so within this network or not.
  3. Call Control/Switching: Call control or switching functionality decides the future course of call based on the call signalling processing. E.g. switching functionality may decide based on the "called number" that the call be routed towards a subscriber within this operator's network.
  4. 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 Accounting
  5. 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 transfer) by user or implicitly (call waiting). 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.
  6. Gateways: 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.

[edit] Other functions

Besides above mentioned functionalities, 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.
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