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Name, addresses, ports, and routes (RFC0814)

IP.com Disclosure Number: IPCOM000003863D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 13 page(s) / 25K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D.D. Clark: AUTHOR


It has been said that the principal function of an operating system

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 11% of the total text.

RFC: 814


David D. Clark

MIT Laboratory for Computer Science

Computer Systems and Communications Group

July, 1982

1. Introduction

It has been said that the principal function of an operating system

is to define a number of different names for the same object, so that it

can busy itself keeping track of the relationship between all of the

different names. Network protocols seem to have somewhat the same

characteristic. In TCP/IP, there are several ways of referring to

things. At the human visible interface, there are character string

"names" to identify networks, hosts, and services. Host names are

translated into network "addresses", 32-bit values that identify the

network to which a host is attached, and the location of the host on

that net. Service names are translated into a "port identifier", which

in TCP is a 16-bit value. Finally, addresses are translated into

"routes", which are the sequence of steps a packet must take to reach

the specified addresses. Routes show up explicitly in the form of the

internet routing options, and also implicitly in the address to route

translation tables which all hosts and gateways maintain.

This RFC gives suggestions and guidance for the design of the

tables and algorithms necessary to keep track of these various sorts of

identifiers inside a host implementation of TCP/IP.


2. The Scope of the Problem

One of the first questions one can ask about a naming mechanism is

how many names one can expect to encounter. In order to answer this, it

is necessary to know something about the expected maximum size of the

internet. Currently, the internet is fairly small. It contains no more

than 25 active networks, and no more than a few hundred hosts. This

makes it possible to install tables which exhaustively list all of these

elements. However, any implementation undertaken now should be based on

an assumption of a much larger internet. The guidelines currently

recommended are an upper limit of about 1,000 networks. If we imagine

an average number of 25 hosts per net, this would suggest a maximum

number of 25,000 hosts. It is quite unclear whether this host estimate

is high or low, but even if it is off by several factors of two, the

resulting number is still large enough to suggest that current table

management strategies are unacceptable. Some fresh techniques will be

required to deal with the internet of the future.