RFCs for Remote Access Networks

There appear to be two schools of thought on
Request for Comments (RFCs)
�"the documents
that are used to establish and document standards in computer networking. Some believe that
only geeks bother to memorize and recite the various RFC numbers, whereas others believe
that such knowledge is critical to the proper design and administration of the network.
Regardless of your individual position, the RFCs that document PPP are worthy of your time
and attention. The various protocols are well documented and invaluable in troubleshooting.
Some of the RFCs that warrant specific attention include the following:
RFC 1334
includes the PPP authentication protocols.
RFC 1661
includes the current revision of the PPP protocol.
RFC 1990
includes the PPP Multilink protocol, which is discussed later in this chapter.
There are many RFCs that would augment this brief list, but their relevance is highly variable
depending on the installation requirements. The Internet Engineering Task Force (IETF) website
at
www.ietf.org
provides links to all RFCs; other sources are available as well.

The PPP protocol adds a minimal amount of overhead to the packet, as illustrated in

The PPP frame structure

Flag (8 bits) Address (8 bits) Control (8 bits) Protocol (16 bits)
Information (variable) FCS (16 bits) Flag (8 bits)

The remainder of this section describes each of the components found in the PPP frame.