The Local Peer Discovery protocol is an extension to the BitTorrent file-distribution system. It is designed to support the discovery of local BitTorrent peers, aiming to minimize the traffic through the Internet Service Provider

Internet service provider

An Internet service provider is a company that provides access to the Internet. Access ISPs directly connect customers to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and host other people servers...

's channel and maximize use of higher-bandwidth

Bandwidth (computing)

In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...

 local area network

Local area network

A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...

 (LAN).

Local Peer Discovery is implemented with HTTP-like messages on User Datagram Protocol

User Datagram Protocol

The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring...

 multicast

IP Multicast

IP multicast is a method of sending Internet Protocol datagrams to a group of interested receivers in a single transmission. It is often employed for streaming media applications on the Internet and private networks. The method is the IP-specific version of the general concept of multicast...

 group 239.192.152.143:6771 which is an administratively scoped multicast address. While it is implemented in several clients (µTorrent, BitTorrent/Mainline, MonoTorrent, libtorrent

Libtorrent (Rasterbar)

libtorrent is an open source implementation of the BitTorrent protocol. It is written in and has its main library interface in C++. Its most notable features are support for Mainline DHT, IPv6 , HTTP seeds and µTorrent's peer exchange....

 and its derivatives, Transmission 2.0 ) and implementation is very simple, no formal specification had been created as of December, 2009 (although it was supposed to be described in nonexistant BEP 14 by Harrison, Hazel). Alternative multicast protocol extension is published as BEP 26. Advice, don't use local peer discovery if you don't have a local network with BitTorrent