BEP:4
Title:Assigned Numbers
Version:11031
Last-Modified:2008-02-28 16:43:58 -0800 (Thu, 28 Feb 2008)
Author:David Harrison <dave at bittorrent.com>
Status:Active
Type:Process
Created:10-Jan-2008
Post-History:

This document describes the known bit allocations and message IDs for the BitTorrent protocol. To request a bit allocation contact editor@bittorrent.org. Contact the same address if you are aware of any omissions.

Reserved Bit Allocations

reserved[0]
0x80  Azureus Messaging Protocol

reserved[5]
0x10  LTEP (Libtorrent Extension Protocol)

reserved[7]
0x01  BitTorrent DHT
0x04  suggest, haveall, havenone, reject request, and allow fast extensions

Reserved Message IDs

Core Protocol:
0x00   choke
0x01   unchoke
0x02   interested
0x03   not interested
0x04   have
0x05   bitfield
0x06   request
0x07   piece
0x08   cancel

DHT Extension:
0x09   port

Fast Extensions:
0x0D   suggest
0x0E   have all
0x0F   have none
0x10   reject request
0x11   allowed fast

Additional IDs used in deployed clients:
0x14   LTEP Handshake (implemented in libtorrent, uTorrent,...)