OpenBGPD

OpenBGPD is a FREE implementation of the Border Gateway Protocol, Version 4. It allows ordinary machines to be used as routers exchanging routes with other systems speaking the BGP protocol.
Started out of dissatisfaction with other implementations, OpenBGPD is a fairly complete BGP implementation, powering many sites. Users often praise its ease of use and high performance, as well as its reliability.
OpenBGPD's companions, ospfd(8), ospf6d(8), ripd(8) and dvmrpd(8) add support for the respective protocols. ldpd(8) and mpe(4) add MPLS support. rpki-client(8) facilitates validation of the Route Origin of a BGP announcement.
OpenBGPD is primarily developed by Claudio Jeker, Theo Buehler, Henning Brauer, and Peter Hessler. All of these daemons are part of the OpenBSD Project.
The portable version, maintained by Claudio Jeker, is available via periodic tarball releases. Contributions are welcome to both the OpenBGPD core and the portable build framework.
The software is freely usable and re-usable by everyone under a BSD license.