Mpd is a netgraph(4) based implementation of the multi-link PPP
protocol for FreeBSD.  It is designed to be both fast and flexible.
It handles configuration and negotiation in user land, while routing
all data packets strictly in the kernel.  It supports several of
the numerous PPP sub-protocols and extensions, such as:

      Multi-link PPP capability 
      PAP, CHAP, and MS-CHAP authentication 
      PPP compression and encryption
      Point-to-Point Tunnelling Protocol (PPTP)
      PPP over Ethernet (PPPoE)
      RADIUS (authentication and accounting)

Mpd also includes many additional features: 

      Dial-on-demand with idle timeout 
      Multiple active connections running simultaneously 
      Dynamic demand based link management (also known as ``rubber bandwidth'') 
      Powerful chat scripting language for asynchronous serial ports 
      Pre-tested chat scripts for several common modems and ISDN TAs
      Clean device-type independent design 
      Comprehensive logging 

WWW: http://sourceforge.net/projects/mpd/