Editing Lancast

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'''Lancast''' allows clients in the same LAN (or VPN) to share their files at a very high speed, providing them with the ability of finding sources and files (keyword searches are available only on ''Lancast version&nbsp;2;'' the first version of Lancast looks for ed2k hashes only) inside their LAN or VPN.

Lancast does not require an ed2k server and does not implement a LAN/VPN implementation of Kad network. Lancast relies on UDP multicasting (and thus may require IGMP support in the LAN or VPN where the clients reside; people may use UDP multicast streaming features of the [http://wiki.videolan.org/ VLC media player] to find&nbsp;out whether multicasting works in their net).

It is a common misconception that Lancast uses UDP multicasting also for file transfer. '''In fact, it doesn't!''' Files are served over regular ''(unicast)'' connections.

For file transfer a modified [[Upload Bandwidth Throttler]] is used which provides a separate upload limit for LAN/VPN clients. Simpler implementations of Lancast use just unlimited upload.

LAN/VPN download is usually always unlimited; however, Lancast Version 2 in [[NeoMule]] provides its [[Download Bandwidth Throttler]] which also has an ability to manage LAN/VPN download speed.

Lancast is not usable over the Internet since multicast is disabled by 99,9% of all providers (except [http://wiki.videolan.org/MBONE MBONE]) and because Lancast wouldn't bring any speed advantages over ed2k/Kad anyway.

== Implementations ==

The Lancast feature is currently available in the following mods:

* Lancast version 2 — in [[NeoMule]] since v4.x,

* Lancast version 1 — in [http://wikipedia.org/wiki/EMule_Plus eMule Plus] and [[Sivka]].

Lancast is also in the «to do list» of features for the [[MorphXT]], but is not likely to be implemented soon.

== Value ==

Since [[Webcache]] has become [[Webcache#Criticism|criticized]] and [[Webcache#Abandoned|abandoned]], the Lancast feature now remains as one of the most advantageous tools allowing for Internet providers to economize their external traffic. By promoting the use of Lancast-capable mods of eMule in LANs and/or VPNs, all the file exchange ed2k/Kad traffic between the clients of the same provider becomes local (otherwise the traffic would twice traverse the local/Internet boundary).

== Comparison with μTorrent ==

According to [http://download.utorrent.com/utorrent-help.zip μTorrent help file] (Appendix A, «Preferences» section, «BitTorrent» subsection), μTorrent has a&nbsp;similar feature called '''Enable Local Peer Discovery:'''

:: '''Enable Local Peer Discovery''' allows µTorrent to attempt to discover local peers via multicast. If a&nbsp;peer is considered local, transfer rates with the&nbsp;peer will not be limited unless ''Limit local peer bandwidth'' is also enabled. Local Peer Discovery will not be used for .torrent files with the 'private' flag set.

== Technical details ==
Judging from a quick glance over Sivka's code, implementing '''Lancast version 1''' involves at least the following changes in&nbsp;the&nbsp;code:

* The file <code>Lancast.cpp</code> and the corresponding header <code>Lancast.h</code> are added to the project (the <code>.vcproj</code> file is changed accordingly).

* The file <code>BaseClient.cpp</code> is altered:
** In <code>CUpDownClient::Init()</code>
*** Additional boolean variable <code>m_bLanClient</code> is initialized.
*** ...

== See also ==
* [[VooDoo]]

[[Category:Features]]
[[Category:NeoFeatures]]