Inside Look at the Internet

1.1.1 Nuts-and-Bolts Description
Chapter 1
1.1 What Is the Internet?
1.1.1 Nuts-and-Bolts Description
1.1.2 A Service Description
1.1.3 What Is a Protocol?
1.2 The Network Edge
1.2.1 End Systems, Clients, and Servers
1.2.2 Connectionless and Connection-Oriented Service
1.3 Network Core
1.3.1 Circuit Switching and Packet Switching
1.3.2 Packed-Switched Networks: Datagram Networks and Virtual-Circuit Networks
1.4 Access Networks and Physical Media
1.4.1 Access Networks
1.4.2 Physical Media
1.5 ISPs and Internet Backbones
1.6 Delay and Loss in Packets-Switched Networks
1.6.1 Types of Delay
1.6.2 Queuing Delay and Packet Loss
1.6.3 Delay and Routes in the Internet
1.7 Protocol Layers and Their Service Models
1.7.1 Layered Architecture
1.7.2 Layers, Messages, Segments, Datagrams, and Frames

The public Internet is a worldwide computer network, that is, a network that interconnects millions of computing devices throughout the world.

In Internet world, all of these devices are called hosts or end systems. Hosts or end systems are connected together by communication links. They are indirectly connected to each other through intermediate switching devices know as packed switches.

Different links can transmit data at different rates, with the transmission rate of a link measured in bits/second.

Packet switches come in many shapes and flavors, but two most prominent types in today's Internet are routers and link-layer switches. Both types of switches forward packets toward their untlimate destinations.

From the sending end system to the receiving end system, the sequence of communication links and packet switches traversed by a packet is known as a route or path through the network. Rather than provide a dedicated path between communicating end systems, the Internet uses a technique known as packet switching that allows multiple communicating end systems to share a path, or parts of a path, at the same time.

End systems access the Internet through Internet Service Provider (ISPs) including residential ISPs.End systems, packet switches, and other pieces of the Internet, run protocols that control the sending and receiving of information within the INternet, The Transmission Control Protocol (TCP) and the Internet Protocol(IP) are two of the most important protocols in the Internet. The IP protocols specifices the format of the packets that are sent and received among routers and end systems. The Internet's principal protocols are collectively known ad TCP/IP.

Internet standards are developed by the Internet Engineering Task Force(IETF). The IETF standards documents are called request for comments (RFCs). RFCs started out as general request for comments to resolve architecture problems that faced the precursor to the Internet. These private networks are often referred to as intranets, as they use the same types of host, routers, links, and protocols as the public Internet.