Lec. 3 Point to Point

One of the most common types of WAN connection is the point-to-point connection. Point-to-point connections are used to connect LANs to service provider WANs, and to connect LAN segments within an Enterprise network. A LAN-to-WAN point-to-point connection is also referred to as a serial connection or leased-line connection, because the lines are leased from a carrier (usually a telephone company) and are dedicated for use by the company leasing the lines. Companies pay for a continuous connection between two remote sites, and the line is continuously active and available.
In modern networks, security is a key concern. PPP allows you to authenticate connections using either Password Authentication Protocol (PAP) or the more effective Challenge Handshake Authentication Protocol (CHAP).
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.