Server address management system

Details Server address management system Server address management system

1999-11-08

2001-10-30

Lee, Thomas (Department: 2182)

Electrical computers and digital processing systems: multicomput

Distributed data processing

Client/server

C709S224000, C709S223000, C370S403000

Reexamination Certificate

active

06311208

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an asynchronous transfer mode (ATM) network. More particularly, the present invention relates to a server address management system in an ATM network for managing the addresses of communication terminals due to the nonbroadcast nature of the ATM network.
Currently, a network for connecting computers so that they communicate data to each other is widely used. Such a network is, for example, a local area network (LAN) which is used in an office and other environments on a relatively small scale and the Internet which is used between companies or nations on a relatively large (world-wide) scale. As these networks cannot directly communicate with a public network such as telephone lines, they have been widely used independent of the public network.
Recently an asynchronous transfer mode (ATM) which will enable direct communication between the above-described networks and a public network has been researched and developed. A network operated according to an ATM (hereinafter called ATM network) is a nonbroadcast system in which broadcast communication is not possible different than existing LAN's such as Ethernet (the registered trademark of Xerox Corporation).
FIGS. 2
to
6
illustrate an example in which in a nonbroadcast system the terminals do not know the identifier (hereinafter called address) used for communication between the terminals. First, referring to
FIG. 2
, system configuration will be described. A terminal A
201
is an information processing system such as a personal computer (PC) and a workstation (WS) for managing the address of terminals (terminals B
203
and C
204
in this example) in a system and ADDR
1
is allocated to the terminal A as its address. The terminal A is provided with an address table
206
illustrated in
FIG. 3
in which a terminal name
301
(IP address in TCP/IP network) and a terminal address
302
are stored and functions as an address server.
The terminals B
203
and C
204
are information devices such as a PC or a WS which communicate with another terminal in the system and ADDR
2
and ADDR
3
are respectively allocated as their addresses. SW
202
is communication equipment for connecting terminals in the system via communication wire
207
and switching a communication path and is equivalent to a switching system in a public network. The communication wire
207
connects each terminal and SW
202
. A twisted pair cable or an optical fiber are examples of communication wire
207
.
Next, referring to
FIGS. 4
to
6
, an example in which the terminal B
203
communicates with the terminal C
204
will be described. This example is known as address resolving as described in “Classical IP and ARP over ATM”, by M. Lauback, Internet Engineering Task Force, Network Working Group Request for Comments; 1577 Category: Standards Track, January 1994, pp 1-17.
As the terminal B
203
not provided with an address table does not know the address of another terminal in the system, it cannot communicate with the other terminal. The reason why only the address server
201
is provided with the address table
206
is that if an address table is distributed, it is difficult to match table information and that in the case of a large-scale system including many terminals, a workload for generating a table is enormous.
Therefore, the terminal B
203
inquires of the address of the terminal C
204
to the address server
201
which manages an address. However, as the terminal B
203
does not also know the address of the address server
201
while it is activated, any of the following three methods is executed:
(1) An operator enters the address (ADDR
1
) of the address server
201
in the terminal B
203
as shown in FIG.
4
.
(2) The address of the address server
201
is stored in the terminal B
203
and the address is used.
(3) The terminal B
203
communicates using a fixed address (a well-known address) and SW
202
converts it to the actual address of the address server
201
.
In an ATM network the above methods (1) and (2) are mainly used and method (3) is used for LAN emulation which is one of the communication modes of ATM network. The terminal B
203
which obtains the address of the address server
201
according to the above method requests the address server
201
to provide to it the address of the terminal C
204
.
The address server
201
which receives the request checks the address table
206
and sends ADDR
3
which is the address of the terminal C
204
to the terminal B
203
as a response as shown in FIG.
5
. The terminal B
203
which receives the address (ADDR
3
) of the terminal C
204
communicates with the terminal C
204
using the address as shown in FIG.
6
.
The above example illustrates the following problems which exist in conventional technology.
(1) When the address of an address server is entered manually in each terminal, the work load of the operator increases in proportion to the number of terminals.
(2) If plural address servers are added to a system when the address of a particular address server is stored or a well-known address is used, the added address servers cannot be selected until modifications to the system are made.
(3) If a failure occurs in an address server, another terminal cannot take over the function of the failed address server as a substitute server until the address of the substitute server has been registered in each terminal.
SUMMARY OF THE INVENTION
The present invention provides an address server for use in a communication system wherein the address server collectively manages addresses each of which is the identification for communication to a terminal in a network of a nonbroadcast system type. The present invention includes an address management section for managing the address of the address server, wherein the address management section is provided in a switch (SW) for connecting each terminal, and an address processing section is provided in each terminal and the address server for registering and obtaining the address of the address server.
The address processing section of the address server sends the address of the address server to the switch. The address management section of the switch registers the received address of the address server in a first table included in the switch and sends the address of the address server to each of the terminals in response to an address from each terminal. The address processing section of each terminal sends its address to the switch and registers the address of the address server sent from the switch in a second table. The address management section of the switch receives the terminal address sent from each terminal and registers it in the first table.
Thus, according to the present invention each terminal obtains the address of the address server without it being previously set and requests the address server to receive its address.
According to the present invention, a third table is provided in the address server. The address processing section of each terminal sends its address to the address server based upon the registered address of the address server and the address processing section of the address server registers the address sent from the terminal in the third table.
The first table of the address management section of the above switch is a logical network table for registering each terminal in units of a logical network in which terminals in a network are logically grouped. The address management section registers and manages the address of the address server and each terminal in units of the logical network and sends the address of an address server which belongs to the same logical network as a terminal to the terminal when the address of the terminal is received from the address processing section of the terminal.
The above address management section is provided with a table processing section for initializing, registering, updating and retrieving the above logical network table and a request processing section for sending or receiving a request to/from each t

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