Point to Point Protocol (PPP)

What PPP Is and Why It Exists

The Point to Point Protocol (PPP) is a communication protocol that creates a dedicated, direct connection between two devices. Unlike protocols that manage complex networks with many nodes, PPP is designed for a simple, one-to-one link. Its core job is to define exactly how two devices will authenticate each other and then establish a direct link so they can exchange data reliably.

Where PPP Is Used

The textbook gives two concrete examples of PPP in action:

• Router-to-router links: Two routers that are directly connected by a cable or a leased line communicate using PPP. This is common in the backbone of the internet and in corporate networks.
• Home internet connections: When you connect your home computer to your Internet Service Provider's (ISP) server through a modem (for example, an old dial-up modem or a DSL modem), that connection typically uses PPP. The modem creates a point-to-point link between your computer and the ISP.

Key Features of PPP

The protocol has several important characteristics that the textbook highlights:

• Authentication: PPP defines how the two devices verify each other's identity before data exchange begins. This prevents unauthorised access.
• Dedicated and direct connection: The link is exclusive to the two communicating devices — no other device shares that path.
• Duplex mode required: Both devices must support duplex communication (the ability to send and receive data simultaneously) for PPP to work.
• Data integrity: PPP ensures that data arrives in the correct order. It does this by tracking the sequence of packets.
• Error handling: If a packet is damaged or lost during transmission, PPP informs the sender and asks it to resend that packet. This guarantees that the data received is complete and uncorrupted. …