1 Telecommunication networks and digital subscriber lines
1.2 Telecommunication network

It has already been mentioned that the telecommunications network must be structured in a certain way. Usually divided into two main parts – core (backbone) and access. Both have their challenges and characteristics.

The core telecommunications network aims to interconnect various network nodes of telecommunications provider. All data transactions are concentrated in these nodes from all subscribers and after that it can be effectively transferred through the shared telecommunications paths through wide geographic area. Typical for this network is:

- standardized transmission medium is single-mode optical fiber,
- transmission speed range in the tens Gbit/s,
- operational distances are from tens to thousands kilometers,
- ring topology is a typical network topology.

Access telecommunication networks mean part of the telecommunications network, which is the last point between provider and subscriber. Over the last point, the ISP (Internet Service Provider) is usually considered local exchange HOST or RSU (Remote Subscriber Unit). Harness coming from the main distribution switchboard (or from RSU) in the network and street cabinets gradually branches into different directions to end subscribers. Typical for this network is:

- transmitting medium is symmetrical metallic pair (single-mode optical fibers are optional),
- transmission speed range from ones up to hundreds Mbit/s,
- operational distance is hundreds meters to ones kilometers,
- commonly occurring network topology is a tree topology.