Minimum bandwidth guarantee for cross-point buffer switch

Details Minimum bandwidth guarantee for cross-point buffer switch Minimum bandwidth guarantee for cross-point buffer switch

1999-07-02

2003-09-23

Chin, Wellington (Department: 2664)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S412000

Reexamination Certificate

active

06625160

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a method and system to be utilized in data communications. In particular, the present invention is related to a method and system to be utilized in data communications involving at least one data communications network.
2. Description of the Related Art
Data communications is the transfer of data from one or more sources to one or more sinks that is accomplished (a) via one or more data links between the one more sources and the one or more sinks (b) according to a protocol. A data link is the means of connecting communications facilities or equipment at one location to communications facilities or equipment at another location for the purpose of transmitting and receiving data. A protocol, in communications, computer, data processing, and control systems, is a set of formal conventions that govern the format and control the interactions between at least two communicating functional elements in order to achieve efficient and understandable communications. Examples of protocols are Internet Protocol (IP) and Asynchronous Transfer Mode (ATM) protocol.
A data communications network is the interconnection of three or more communicating entities (i.e., data sources and/or sinks) over one or more data links. A data communications network connects and allows communication between multiple data sources and multiple data sinks over one or more data links. The concept of a data link includes the media connecting the one or more data sources to one or more data sinks, as well as the data communications equipment utilizing the media. The data communications networks utilize protocols to control the interactions between data sources and sinks communicating over the one or more data links. Thus, it follows that such protocols must take into account the data communications requirements of data sources and sinks desiring communication over the one or more data links.
Referring now to
FIG. 1
, shown is a partially-schematic diagram of a related art data communications network. Depicted are six data sources/sinks: data source/sink A
100
, data source/sink B
102
, data source/sink C
104
, data source/sink D
106
, data source/sink E
108
, and data source/sink F
110
. The depicted six data sources/sinks are connected by/through data communications network
112
. Illustrated is that data communications network
112
is composed of numerous data communications links
150
-
184
and network nodes
116
-
128
. Shown is that within each network node
116
-
128
resides crossbar switches
130
-
142
, respectively.
Historically, each crossbar switch
130
-
142
, was a switch that had a number of vertical paths, a number of horizontal paths, and electromagnetic-operated mechanical devices, i.e., electromechanical relays, for interconnecting any one of the vertical paths with any one of the horizontal paths. (While the foregoing is historically truth those skilled in the art will recognize that the logical functions of crossbar switches are generally performed using combinational circuits; however, the term “crossbar” switch has been retained for such combinational circuits even though such circuits typically no longer actually utilize a true physical “crossbar.”) Thus, the electromagnetic-operated mechanical devices within each crossbar switch
130
-
142
can be utilized to interconnect at least one data communications link on one side of any particular crossbar switch to at least one data communications link on the other side of the particular crossbar switch. For example, crossbar switch
130
internal to network node
116
contains circuitry sufficient to connect any one of data communications links
150
-
154
with any one of data communications links
156
-
162
. Likewise, crossbar switch
136
internal to network node
122
contains circuitry sufficient to connect any one of data communications link
163
,
166
,
170
with any one of data communications links
174
-
176
. The same holds true for the other crossbar switches depicted in FIG.
1
.
When data communications is desired between any two data sources/sinks (e.g., data source/sink A
100
with data source/sink D
106
, data source/sink B
102
with data source/sink F
100
, or data source/sink C
104
with data source/sink E
108
) appropriate crossbar switches
130
-
142
can be utilized to establish hardwire paths between the data source/sink pair. At present, there are two basic ways in which crossbar switches
130
-
142
can be utilized to establish a communications path through data communications network
112
: (1) by use of what is known in the art as “circuit switching”; and (2) by use of what is known in the art as “packet switching.” The present invention is related to crossbar switches in packet-switched networks. However, before packet-switched networks are discussed, the functioning of crossbar switches in a circuit-switched network is discussed because discussing the functioning of crossbar switches in a circuit switched network serves as a good introduction to discussing the functioning of crossbar switches in packet-switched networks.
Referring now to
FIG. 2
, shown are three “circuit switched” paths which are used to introduce the functioning of crossbar switches. In what is known in the art as “circuit switching,” an actual physical circuit is established between each data source/sink pair. Depicted in
FIG. 2
is circuit switched path
1
connecting data source/sink A
100
with data source/sink D
106
. Illustrated is that circuit switched path
1
is composed of data communications link
150
-network node
116
-data communications link
162
-network node
126
-data communications link
178
-network node
124
-data communications link
170
-network node
122
-data communications link
174
. With respect to circuit switched path
1
, shown is that crossbar switch
130
connects data communications link
150
with data communications link
162
, crossbar switch
140
connects data communications link
162
with data communications link
178
, crossbar switch
138
connects data communications link
178
with data communications link
170
, crossbar switch
136
connects data communications link
170
with data communications link
174
. Also depicted is circuit switched path
2
connecting data source/sink B
102
with data source/sink F
110
. Circuit switched path
2
, and each of the depicted components making up circuit switched path
2
, functions in a manner similar to that described in relation circuit switched path
1
. Further depicted is circuit switched path
3
connecting data source/sink C
104
with data source/sink E
108
. Circuit switched path
3
, and each of the depicted components making up circuit switched path
3
, also functions in a manner similar to that described in relation circuit switched path
1
.
Referring now to
FIG. 3
, shown is the use of “packet switching” to transmit data through data network
112
, and how crossbar switches are utilized in a packet-switched network. In what is known in the art as “packet switching,” data to be transmitted between each data source/sink pair is encapsulated in a “packet” which, in data communications, is a sequence of binary digits that (a) includes data, control signals, and possibly error control signals, and (b) is arranged in a specific format, such as a header part and data part, wherein the header part generally contains information indicative of the source and destination of the data part of the packet (thus, as used, the term “packet” includes all such unitized data, such as, for example IP packets or ATM cells. Whereas in circuit switching, crossbar switches
130
-
142
were keyed to and switched, or controlled, upon the basis of a circuit to be established throughout data communications network
112
throughout the duration of a call, in “packet switching” crossbar switches
130
-
142
are keyed to, and switched upon, the basis of header information (e.g., the source and destination information contained within the header). That is, each crossbar s

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