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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  Name Systems and TCP/IP Name Registration and Name Resolution            9  Name System Issues, Concepts and Techniques

Name Spaces and Name Architectures (Flat and Hierarchical) 1 2 Name Resolution Techniques and Functional Elements of A Name Resolution System

Name Registration Methods

There are several common methods by which the actual process of registration is carried out. Each of these has its strengths and weaknesses, and again, some are better-suited to flat name spaces and some to hierarchical ones.

In this technique, name assignments are maintained in a table by an administrator. When names need to be added, deleted or changed the table is edited.

This technique is usually associated with small, flat name space name systems, and has the same benefits and drawbacks as flat architecture in general: it is simple and easy to implement, but doesn't scale well to larger systems. With a dozen machines, having someone edit name registration tables is practical; with thousands of machines it is not. It is also not conducive to a hierarchical system where there are multiple authorities, because the table needs to be kept in one place.

In larger internetworks, tables may be used as an adjunct to one of the more sophisticated techniques below.

This is a “trial and error” technique; a device that wants to use a particular name sends out a message to all other devices on the network asking to see if anyone else is already using it. If so, it chooses a different name. If not, the name is considered registered and can then be used.

This technique is more sophisticated than using tables, but is still limited to use in relatively small systems. It is not practical to attempt to broadcast to thousands of systems, and this method could not be used over the Internet, since there is no way to broadcast to every device on an internetwork.

A database of name assignments is maintained. To register a name, a request must be made to have the name assignment added to the database. If the authority for the name system is entirely centralized, the database will be centralized and maintained by that authority. If authority for parts of the hierarchy is delegated, then a distributed database is used for registration, with each authority maintaining the part of the database describing their section of the hierarchy.

This is the most sophisticated technique, and one normally associated with hierarchical name systems like DNS. It has several benefits, including flexibility, reliability and distribution of maintenance effort; its main drawback is complexity.

We have just seen that the choice of name space and architecture immediately has an important impact on how name registration is done. The next topic will show how name resolution is closely related to name registration and architecture as well.

Name Spaces and Name Architectures (Flat and Hierarchical) 1 2 Name Resolution Techniques and Functional Elements of A Name Resolution System