Asynchronous Layered Coding

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Asynchronous Layered Coding is an Internet protocol of the IETF specified in RFC 3450 and described as a massively scalable reliable content delivery protocol. It was adopted as an experimental protocol in December of 2002 and still is as of January 2006.

  Asynchronous Layered Coding (ALC)is a massively scalable 
  reliable content delivery protocol, for multiple
  rate congestion controlled reliable content delivery.  The protocol
  is specifically designed to provide massive scalability using IP
  multicast as the underlying network service.  Massive scalability in
  this context means the number of concurrent receivers for an object
  is potentially in the millions, the aggregate size of objects to be
  delivered in a session ranges from hundreds of kilobytes to hundreds
  of gigabytes, each receiver can initiate reception of an object
  asynchronously, the reception rate of each receiver in the session is
  the maximum fair bandwidth available between that receiver and the
  sender, and all of this can be supported using a single sender.

  Because ALC is focused on reliable content delivery, the goal is to
  deliver objects as quickly as possible to each receiver while at the
  same time remaining network friendly to competing traffic.  Thus, the
  congestion control used in conjunction with ALC should strive to
  maximize use of available bandwidth between receivers and the sender
  while at the same time backing off aggressively in the face of
  competing traffic.

  The sender side of ALC consists of generating packets based on
  objects to be delivered within the session and sending the
  appropriately formatted packets at the appropriate rates to the
  channels associated with the session.  The receiver side of ALC
  consists of joining appropriate channels associated with the session,
  performing congestion control by adjusting the set of joined channels
  associated with the session in response to detected congestion, and
  using the packets to reliably reconstruct objects.  All information
  flow in an ALC session is in the form of data packets sent by a
  single sender to channels that receivers join to receive data.

  ALC does specify the Session Description needed by receivers before
  they join a session, but the mechanisms by which receivers obtain
  this required information is outside the scope of ALC.  An
  application that uses ALC may require that receivers report
  statistics on their reception experience back to the sender, but the
  mechanisms by which receivers report back statistics is outside the
  scope of ALC.  In general, ALC is designed to be a minimal protocol
  instantiation that provides reliable content delivery without
  unnecessary limitations to the scalability of the basic protocol.