Log Message:
Import openpgm-5.2.122 as wip/openpgm.

OpenPGM is an open source implementation of the Pragmatic General Multicast
(PGM) specification in RFC 3208 available at www.ietf.org. PGM is a reliable
and scalable multicast protocol that enables receivers to detect loss, request
retransmission of lost data, or notify an application of unrecoverable loss.
PGM is a receiver-reliable protocol, which means the receiver is responsible for
ensuring all data is received, absolving the sender of reception responsibility.
PGM runs over a best effort datagram service, currently OpenPGM uses IP
multicast but could be implemented above switched fabrics such as InfiniBand.