Lec. 4 Point to point configration

PPP Configuration Options
•PPP can be configured to support various functions including:
•Authentication using either PAP or CHAP
•Compression using either Stacker or Predictor
•Multilink which combines two or more channels to increase the WAN bandwidth.
How Does Serial Communication Work?
Most PCs have both serial and parallel ports. You also know that electricity can move at only one speed. To transfer data quicker, it can be compressed and therefore require fewer bits to be transmitted. An alternative method is to transmit the bits simultaneously,
as done in computers with parallel connections. Computers use relatively short parallel connections between interior components, but they use a serial bus to convert signals for most external communications. Let’s compare serial and parallel communications.
A parallel connection sends the bits over more wires simultaneously. In the case of the 25-pin parallel port on your PC, eight data-carrying wires carry 8 bits simultaneously. Because eight wires carry the data, the parallel link theoretically transfers data eight times faster than a serial connection. So, based on this theory, a parallel connection sends a byte in the same amount of time a serial connection takes to send a bit.
PAP Authentication Protocol
•PPP defines an extensible LCP that allows negotiation of an authentication protocol for authenticating its peer before allowing Network layer protocols to transmit over the link. RFC 1334 defines two protocols for authentication, as shown in the figure.