Project PDA

Point-to-point networking is useful for networking two computers together. If one of the peers permits routing or bridging to a wider network, then the other gains access to that network. This is what happens when you dial up your Internet service provider on a traditional modem. PPP networking is used in the implementation of the Bluetooth LAN access profile.

PPP was designed somewhat after the original HDLC specifications. The designers of PPP included many additional features that had been seen only in various proprietary data-link protocols up to that time.

PPP is described by Internet Engineering Task Force (IETF) RFC 1661.

PPP permits multiple network layer protocols to operate on the same communications link. For every network layer protocol used, a separate Network Control Protocol (NCP) is provided in order to encapsulate and negotiate options for the multiple network layer protocols.

For example, Internet Protocol (IP) uses the IP Control Protocol (IPCP), and Internetwork Packet Exchange (IPX) uses the Novell IPX Control Protocol (IPXCP). NCPs include fields containing standardized codes to indicate the network layer protocol type that PPP encapsulates.

Both PPP and Dynamic Host Configuration Protocol (DHCP) offer support for automatic configuration of interfaces. While DHCP is used primarily for multi-point access, it may also be used on point-to-point links only after PPP has completed establishment of the essential link and network configuration.

The states of the Point to Point Protocol are such:

• Dead (or idle), no active connection or carrier.
• Establish, where Link Control Protocol negotiation begins.
• Authenticate, where two terminal points authenticate each other. Either PAP, or CHAP protocol comes in use at this point.
• Network, where the appropriate Network Control Protocol is invoked. IPCP comes in use to establish IP service over the network
• Open, where data transport takes place.
• Terminate, where the connection requires termination
  

Allo see Softick PPP, PPPoE, PicoBlue Internet Access Point.