Point-to-Point Protocol

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Point-to-point protocol (PPP) is intended for a wide range of computer communications over media that use a physical (e.g., dialup) or logical (e.g., point-to-point over LANs) topology.[1] It can negotiate a wide range of protocol options for the specific connection, making it more flexible than earlier protocols for point-to-point topologies. While the capability is much less needed in an Internet Protocol-centric world, it can also set up connetions for non-IP protocols, such as IBM or Novell proprietary protocols, and for bridging. It can also be used in combination with a wide range of tunneling and securty protocols.

Basic protocol operations

Extended applications

Dynamic address assignment

PPP has an extension, the PPP Internet Protocol Control Protocol, which can dynamically assign an IP address to the client. This is common with dialup and other links where the end host connection to the overall network will be part of the subnet associated with the access server.[2]

Dynamic DNS update with dynamically assigned addresses

For operational convenience, it is best to assign a Domain Name Service (DNS) name to dynamically assigned addresses. DNS supports a dynamic update mechanism for just such assignments. [3] Such an update is an invitation to attack unless secured, so dynamic DNS update should always be associated with a specific secure update mechanism,[4] within the DNS security architecture.[5]

Error control

PPP optionally can drop and retry a connection with an excessive error rate. While there is a PPP option that allows error control by retransmission, when using PPP in an IP network, it is usually best to let Transmission Control Protocol do the retrnsmission.

Use with tunnels

The Layer 2 tunneling protocol allows a PPP link to be established over any medium, which is useful in many transition and mobility applications.

References

  1. W. Simpson, ed. (July 1994), The Point-to-Point Protocol (PPP), RFC1661
  2. R. Arends, R. Austein, M. Larson, D. Massey, S. Rose (May 1992), G. McGregor, RFC1332
  3. S. Thomson, Y. Rekhter, J. Bound. (April 1997), P. Vixie, ed., Dynamic Updates in the Domain Name System (DNS UPDATE), RFC2136
  4. B. Wellington (November 2000), Secure Domain Name System (DNS) Dynamic Update, RFC3007
  5. R. Arends, R. Austein, M. Larson, D. Massey, S. Rose (March 2005), DNS Security Introduction and Requirements, RFC4033