Electrical computers and digital processing systems: multicomput – Multiple network interconnecting
Reexamination Certificate
1996-12-26
2002-12-10
Jones, Hugh M. (Department: 2123)
Electrical computers and digital processing systems: multicomput
Multiple network interconnecting
C709S245000, C709S238000, C709S230000, C709S241000
Reexamination Certificate
active
06493767
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a network system and a line concentrator for constructing the network system,
2. Description of the Prior Art
A shared media type of network has hitherto been adopted as a basic structure in a prior art network system, e.g., in a LAN (Local Area Network) system represented by Ethernet. That is, there is adopted a construction for receiving and transferring data by use of communication lines for connecting a plurality of terminal equipments to each other. Therefore, the terminal equipments connected to the same LAN share a bandwidth with each other. Accordingly, when a traffic volume increases, the bandwidths of the communication lines come to deficiency enough to cause such a case that the smooth transmission and receipt of the data might be hindered. One of countermeasures against this problem may be a network system using a line concentrator (e.g. switching HUB).
FIG. 31
is a block diagram illustrating a whole configuration of the network system employing a line concentrator
1
. Referring to
FIG. 31
, a plurality of terminal equipments (hereinafter simply called “terminals”)
2
a
-
2
d
are connected via communication lines to the line concentrator
1
. The data is transferred and received based on packet communications between the respective terminals
2
a
-
2
d.
A packet used at this time is stored with a data-transmitted-side address and a data-transmitting-side address in addition to the data to be transmitted.
Therefore, the respective terminals
2
a
-
2
d
have network addresses (IP addresses (Internet Protocol addresses): layer
3
addresses) of the respective terminals
2
a
-
2
d,
and MAC (Media Access Control) addresses. Then, when one of the terminals
2
a
-
2
d
transmits the data to other terminal, the transmitting terminal generates the packet. This packet is stored with the data-transmitted MAC address and the data-transmitting network address, and the data.
On the other hand, the line concentrator
1
incorporates, as illustrated in
FIG. 31
, a MAC address table
3
stored with the MAC addresses of the terminals
2
a
-
2
d.
When the line concentrator
1
receives the packet from one of the terminals
2
a
-
2
d,
the data-transmitted MAC address stored in the packet is compared with the MAC address stored in the MAC address table
3
, whereby the data-transmitted MAC address is confirmed, and the packet transmitting terminal and the packet transmitted terminal are brought into such a state as to be connected to each other via one communication line.
For example, referring again to
FIG. 31
, in the case of transmitting the data packet from the terminal
2
a
to the terminal
2
c,
when the line concentrator
1
receives the packet transmitted by the terminal
2
a,
the terminal
2
a
is connected via the one communication line to the terminal
2
c
with the MAC address of the terminal
2
c
that is stored in that packet (see the broken line in FIG.
31
). This is known as a port switching function.
With this port switching function, a medium (communication line) is occupied between the terminal
2
a
and the terminal
2
c,
and, besides, the bandwidth is also occupied. Thus, the line concentrator
1
enables the terminals
2
a
-
2
d
to transfer and receive the data through the one-to-one communication. Hence, the data can be smoothly transferred and received.
In contrast with this, there must be a case wherein each of the terminals
2
a
-
2
d
transmits the data to the plurality of terminals. In this case, each of the terminals
2
a
-
2
d
is stored with an address (a broadcast address) purporting that the packet should be transmitted to all the terminals, in an area for storing the packet data-transmitted MAC address. The packet stored with the broadcast designation as the transmitted address is termed a broadcast packet.
This broadcast packet is, when received in the line concentrator
1
, transmitted to the plurality of terminals in accordance with setting of the line concentrator
1
. More specifically, the line concentrator
1
is capable of unifying the plurality of communication lines (an interface accommodating the communication lines) connected to itself by setting, into a single or a plurality of groups. The line concentrator
1
, upon receiving the broadcast packet, distinguishes which group the communication line accepting the transmission of the broadcast packet belongs to, and sends the broadcast packet to the communication line belonging to that group. Herein, a group having such a domain that the line concentrator
1
transmits the broadcast packet is referred to as a broadcast domain.
For example, as shown in a block diagram of
FIG. 32
, if all the communication lines connected to the line concentrator
1
are set as one broadcast domain, and when the line concentrator
1
receives the broadcast packet transmitted from, e.g., the terminal
2
a,
the communication lines for connecting the terminals
2
a
-
2
d
to the line concentrator
1
are connected to each other (see the broken line in FIG.
32
), and the broadcast packet is thereby transmitted from the line concentrator
1
to the terminals
2
b
-
2
d.
By the way, as illustrated in
FIG. 33
, there may be a case where a terminal
2
e
is newly connected via the communication line to the line concentrator
1
in the network system shown in FIG.
31
. The terminal
2
e
immediately after being connected is in such a state as to possess the network address at all.
In anticipation of such a case, as illustrated in
FIG. 33
, an address possession server
4
(hereinafter simply termed a “server”) is connected via the communication line to the line concentrator
1
in the network system. Herein, the server
4
possesses a self network address (hereinafter called a “server address”) and a single or a plurality of an unused network address. This server
4
, upon receiving a supply request of the network address from the terminal, supplies the unused network address possessed by the server
4
itself.
Given hereinbelow is an explanation of a process when the server supplies the network address to the terminal
2
e in
FIG. 33. A
premise is that the line concentrator
1
is set to transmit, upon receiving the broadcast packet, this broadcast packet to all the terminals
2
a
-
2
e
and the server
4
that are connected to the line concentrator
1
.
At first, the terminal
2
e
transmits a broadcast packet (“address possession server_DISCOVER packet” hereinafter called a “DISCOVER packet”) in which the data is a supply request for the server address and the unused network address. The reason why the “DISCOVER packet” is defined as the broadcast packet is that the terminal
2
e
immediately after being connected to the network system is in such a state that a position (address) of the server
4
is unknown. The terminals
2
a
-
2
d
and the server
4
receive this “DISCOVER packet” via the line concentrator
1
.
Next, when the server
4
receives the “DISCOVER packet”, there is transmitted a broadcast packet (“address possession server_“OFFER packet”: hereinafter called an “OFFER packet”) in which the data consists of the server address of the server
4
and a single or a plurality of unused network addresses. The reason why the “OFFER packet” is defined as the broadcast packet is that the terminal
2
e
is in such a state as to have no self address, and therefore the server
4
is impossible of specifying the terminal to which the “OFFER packet” should be transmitted from the “DISCOVER packet”. The terminals
2
a
-
2
e
receive this “OFFER packet” via the line concentrator
1
.
Next, when the terminal
2
e
receives the “OFFER packet”, the terminal
2
e
selectively obtains one network address from the single or the plurality of unused network addresses, and a broadcast packet (“address possession server_REQUEST packet”: hereinafter called a “REQUEST packet) in which the obtained result serves as a piece of data, is transmitted. This “REQUEST packet” is, as in the case of the “DISCOVER packet”, transmitte
Ishida Toshihiro
Sekihata Osamu
Fujitsu Limited
Staas & Halsey , LLP
Thomson W D
LandOfFree
Network address supply system for transmitting an address... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Network address supply system for transmitting an address..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Network address supply system for transmitting an address... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2958295