RFC 1378 (rfc1378) - Page 2 of 16
The PPP AppleTalk Control Protocol (ATCP)
Alternative Format: Original Text Document
RFC 1378 PPP ATCP November 1992
ACKNOWLEDGEMENTS ............................................. 15
SECURITY CONSIDERATIONS ...................................... 16
CHAIR'S ADDRESS .............................................. 16
AUTHOR'S ADDRESS ............................................. 16
1. Introduction
PPP has three main components:
1. A method for encapsulating datagrams over serial links.
2. A Link Control Protocol (LCP) for establishing, configuring,
and testing the data-link connection.
3. A family of Network Control Protocols (NCPs) for establishing
and configuring different network-layer protocols.
In order to establish communications over a point-to-point link, each
end of the PPP link must first send LCP packets to configure and test
the data link. After the link has been established and optional
facilities have been negotiated as needed by the LCP, PPP must send
NCP packets to choose and configure one or more network-layer
protocols. Once each of the chosen network-layer protocols has been
configured, datagrams from each network-layer protocol can be sent
over the link.
The link will remain configured for communications until explicit LCP
or NCP packets close the link down, or until some external event
occurs (an inactivity timer expires or network administrator
intervention).
2. A PPP Network Control Protocol (NCP) for AppleTalk
The AppleTalk Control Protocol (ATCP) is responsible for configuring,
enabling, and disabling the AppleTalk protocol modules on both ends
of the point-to-point link. ATCP uses the same packet exchange
machanism as the Link Control Protocol (LCP). ATCP packets may not
be exchanged until PPP has reached the Network-Layer Protocol phase.
ATCP packets received before this phase is reached should be silently
discarded.
The AppleTalk Control Protocol is exactly the same as the Link
Control Protocol [1] with the following exceptions:
Frame Modifications
The packet may utilize any modifications to the basic frame format
which have been negotiated during the Link Establishment phase.
Parker