Microsoft Certified Systems Engineer (MCSE) Question:

Point to Point protocol helps communication between 2 computers over a serial cable, phone line or other fiber optic lines. E.g. Connection between an Internet Service Provider and a host. PPP also provides authentication. PPP operates by sending Request packets and waiting for Acknowledge packets that accept, reject or try to change the request. The protocol is also used to negotiate on network address or compression options between the nodes.

Packet format:-

Flag field: 1 byte: - Indicates frames beginning or end
Address field: 1 byte: - Used for broadcast address (destination address)
Control field: 1 byte: - Used as a control byte
Protocol field: - 1 or 2 bytes: - Setting of protocol in information field (of datagram)
Information: - 0 or more bytes: - Datagram (whether it contains data or control information)
Padding: - 0 or more bytes: - optional padding
FCS: - 2 or more bytes: - error check sum