Metallic access network

Written on 4:09 PM by ooe

All developed countries have near ubiquitous metallic access networks and they represent one of many Telcos' largest and most valuable assets. Once limited to providing voice access and voice band modems, the metallic access network is now capable of carrying multi-megabit data services thanks to the introduction of digital subscriber line (DSL) technology made possible by recent developments in micro electronics and in digital signal processing. Each customer access line consists of a pair of wires running from the customer premises to the nearest local exchange. The line consists of a number of elements that provide connection, jointing and cross-connection functionality. The key architectural features of BT's metallic access network in the UK are shown. In the UK, access network cables terminate on a main distribution frame (MDF) within the local exchange building and this represents the cross-connection point between the external network and transmission equipment. There are flexibility points in the external network at primary cross-connection points (PCPs) usually located in cabinets seen in the street and at distribution points (DPs) located close to end-user premises, typically on telephone poles. The wire between the DP and end-user is known as a customer feed or customer drop. Access network cable sizes range from 10 pairs to 4800 pairs. In general, cables near a local exchange building have larger pair counts and smaller conductor sizes. Conversely, nearer to customers, the network cables have smaller pair count and larger conductor diameter.