Introduction to the Internet Protocols

5 is a permanent error, such as a non-existent recipient. The message should be returned to the sender with an error message. Two separate protocols are involved in handling TCP/IP datagrams.

  • This allows two implementations that can handle big datagrams to use them, but also lets them talk to implementations that can’t handle them.
  • If they disagree, then something bad happened to the datagram in transmission, and it is thrown away.
  • RFC 1009 contains a review of gateway design and routing.
  • Chapter 6 considers online services, including CompuServe, American Online, and the Microsoft Network, and the thesis ends with a conclusion in Chapter 7.
  • The parties have the right to be represented by attorneys or other representatives at their own expense in connection with the arbitration.

The numbers allow the user program to respond unambiguously. The rest of the response is text, which is normally for use by any human who may be watching or looking at a log. In this case, the mail server could get the information by looking at the message itself.


Most IP experts recommend that individual computers should not try to keep track of the entire network. Instead, they should start with default gateways, and let the gateways tell them the routes, as just described. However this doesn’t say how the gateways should find out about the routes.The gateways can’t depend upon this strategy.

It is also possible to use the domain system to store information about users, mailing lists, or other objects. Remote terminal connections use another mechanism still. When it is necessary to send a command (e.g. to set the terminal type or to change some mode), a special character is used to indicate that the next character is a command. If the user happens to type that special character as data, two of them are sent. This thesis analyses the evolution of British computer networks and the Internet between the years 1970 and 1995.

Introduction to the Internet Protocols

TCP (the “transmission control protocol”) is responsible for breaking up the message into datagrams, reassembling them at the other end, resending anything that gets lost, and putting things back in the right order. IP (the “internet protocol”) is responsible for routing individual datagrams. However in the Internet, simply getting a datagram to its destination can be a complex job. Keeping track of the routes to all of the destinations and handling incompatibilities among different transport media turns out to be a complex job.