Communication Networks
October 14, 1998

• So far we have addressed the problem of sending information bits from one point to another.
• This problem is often referred to as point-to-point communications or link-layer communications.
• To allow for communications between arbitrary pairs of users it must be possible to establish communication links between any pair of users.
• Example: In the telephone network, (virtually) any phone in the world can be reached by dialing its number.
• Example: On the Internet, information can be retrieved from any WWW server by specifying its address.
• Does that mean that a wire connects any pair of phones in the phone network?
• Or, a separate wire connects your computer to any WWW server on the Internet?