Internet-Pieces

The Pieces of the Internet

• nodes are the machines that are ultimately connected by the network, e.g. computers

• links are the mediums connecting nodes, e.g. a coaxial cable or a wireless link as used in WiFi

  • point-to-point is a link between two nodes
  • multiple-access is a link connecting a various number of nodes

• we can design specific nodes to forward messages along various links, forming a switched network

  • circuit switched establishes a dedicated circuit across a sequence of links, so that a source node can send an uninterrupted stream of bits to the destination node
  • packet switched uses a "store and forward" strategy, where it takes fixed-size blocks of data, called packets, from various sources, stores them in memeory, and then forwards them along towards the destination
  • in this setting, the specific nodes used to connect sources to destinations, that actually perform the "switching" to align the correct links, are called switches
  • the nodes at the ends of the network, that use the network, are called hosts

• we can combine various networks using the same methods, i.e. with links and switches, and doing so results in an internetwork a.k.a. an internet

• we use the capitalized Internet to refer to the TCP/IP internet that we use everyday.

• a node connecting two or more networks is called a router or gateway and functions teh same as a switch in that it just forwards packets among the networks to which it is connected

• the other piece of this is addressing the nodes on the network (e.g. IPv4), and getting the right packets to the destination address is known as routing

  • unicast is single to single routing
  • broadcast is single to all routing
  • multicast is single to (many-but-not-all) routing