Supported Platforms
PPP in Broadband Networks
Point-to-Point Protocol (PPP) is used for communications between two nodes, such as between a client and a server. Originally defined by the IETF in RFC 1661, and used for direct connection between devices over a leased line using ISO 3309 framing, several methods have been defined to establish PPP connections across other media. Because residential broadband services historically used an ATM infrastructure, Point-to-Point Protocol over ATM (PPPoA) was originally the dominant access protocol in service provider networks. However, as networks have transitioned to Ethernet, Point-to-Point Protocol over Ethernet (PPPoE) has emerged as an alternative to PPPoA.
The connection-oriented nature of PPP, indicating the availability of a connection as well as whether IP connectivity is established, is well-suited for a subscriber access network. When links are not active, echo-request and echo-reply packets provide link confirmation for any connected peers. When links are active, these link-checking packets are not sent; the presence of data alone indicates that the link is functioning.
The usage of PPP for subscriber access is not without its challenges, however. As more client connections are managed, the amount of state information maintained by the routers increases. The management of this state information can become more complex when using advanced features and when managing clients dynamically.
