Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1997-11-14
2002-05-21
Hsu, Alpus H. (Department: 2662)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S428000, C379S093030, C358S409000
Reexamination Certificate
active
06393016
ABSTRACT:
COPYRIGHT
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
The portion subject to copyright protection has been defined by placing one copyright notice just prior to the beginning of the copyrighted portion, and placing a second copyright notice just after the end of the copyrighted portion.
BACKGROUND
1. Field of the Invention
The present invention relates to real-time distribution of digitally encoded messages over a data network, such as the Internet. More specifically, the present invention relates to a system and method for controlling transmission of digitally encoded messages using any desired communication protocol, including the native protocol of the communicating devices.
2. Background of the Invention
FIG. 1
is a schematic diagram of a prior art system
101
for real-time transmission of digitally encoded messages (DEMs). Where MCDs
102
and
106
are fax machines, for example, the DEMs are fax messages. MCD
102
sends a DEM to MCD
106
. MCD
102
sends telephony data representative of a DEM to a public-switched telephone network (PSTN)
104
over line
108
using the T.30 protocol. Likewise, the PSTN transmits the telephony data to MCD
106
over line
110
using the T.30 protocol.
The PSTN
104
of system
101
has two attributes that facilitate transmission of DEMs. First, the PSTN
104
provides a guaranteed bandwidth. Once a connection is made, MCD
102
and MCD
106
communicate using the full bandwidth allocated to the telephony connection provided by the PSTN
104
. Second, there is a guaranteed latency between the time that MCD
102
sends the telephony data and the time MCD
106
receives the telephony data.
The PSTN-based transmission of DEMs suffers from several disadvantages. First, long distance charges must often be incurred in completing the DEM transmission from MCD
102
to MCD
106
. Second, the bandwidth of the telephony connection is limited relative to other forms of communication such as communication over data networks. Third, even with full bandwidth of the telephony connection available, many data transfer protocols (for example, fax) can be conducted using less than one tenth—and are designed to use no more than one half—of the full bandwidth available.
To avoid the disadvantages associated with system
101
, DEMs have been transmitted over data communication networks, for example, the Internet.
FIG. 2
illustrates a schematic of a prior art system
241
for transmitting DEMs over a data network. In system
241
, MCD
242
transmits telephony data representative of a DEM to a server
244
over line
250
using the T.30 protocol. Server
244
is assumed to be equipped with a data conversion card (not shown) to convert the telephony data to computer data. Server
244
transmits the computer data to a server
246
over line
252
using the TCP/IP protocol. Line
252
represents a computer network, for example the Internet. The server
246
converts the computer data to telephony data using a card (not shown). The telephony data is transmitted to MCD
248
over line
254
using the T.30 protocol.
There are two disadvantages associated with system
241
. First, there is no guaranteed bandwidth. Although a computer network is capable of providing greater bandwidth than a telephony-based system, there is no guarantee that any bandwidth will be available when it is needed, unless, possibly, the network is dedicated to the transmission of DEMs. Second, there is no guaranteed minimum latency. Thus, there is no guarantee that a DEM sent by MCD
242
will reach MCD
248
within any minimum delay. This is problematic with many DEM transmissions because the MCD
242
and MCD
248
generally must maintain synchronization with one another. For example, where MCDs
242
and
248
are fax machines, they must resynchronize with one another at the end of each transmitted page. For fax machines, this resynchronization must occur within 5 to 7 seconds. If the required resynchronization does not occur within the required time frame, MCDs
242
and
248
will assume that the connection has been lost and they will hang up. Unfortunately, latency over a data network such as the Internet can be on the order of 30 seconds or more. Thus, the prior art system
241
will likely cause disrupted DEM delivery due to lost connections resulting from loss of synchronization because no minimum latency can be guaranteed.
DEFINITIONS
“DEM,” as used herein, shall mean digitally encoded message.
“MCD,” as used herein, shall mean message communicating device. A facsimile machine is one example of an MCD.
“PSTN,” as used herein, shall mean public-switched telephone network.
“DCN,” as used herein, shall mean data communications network, including, but not limited to, wide area networks, intracompany networks, intercompany networks and other internodal networks such as the Internet.
SUMMARY OF THE INVENTION
The present invention solves the problems associated with conventional systems by providing a control process to handle the protocol among nodes transferring DEMs over a data communications network. The control processes on the various nodes communicate with one another to determine any particular node's availability for message communication. If a connection is made for message communication, the control processes on the communicating nodes control message transfer according to a particular protocol, and transfer the DEMs over the DCN in real time. The protocol can be any data communications protocol, including the data communications protocol native to the communicating devices.
The control process in the preferred embodiment includes a parent process and a child process. The parent process is responsible for managing communication between nodes, i.e., the parent process is responsible for managing the DCN aspects of a DEM communication. DEM communication is also referred to herein as a DEM transaction. Thus, the parent process isolates the child process from DCN related functions. The child process controls the hardware aspects of a DEM communication. This control includes managing telephony hardware and performing any telephony related functions. The child process, therefore isolates the parent process from the hardware aspects of DEM communication. Preferably, the child process communicates with a particular MCD using its native protocol. The parent and child work together according to a protocol to ensure that DEM communications are established within the latency time required to maintain synchronization.
When DEMs cannot be transmitted over the data communications network, the control process attempts to route DEMs over a secondary path. The secondary path is also a data network. Thus, the bandwidth and cost advantages associated with transmitting DEMs using data networks rather than telephony lines are preserved. In addition, the secondary path provides an auxiliary route for DEMs when they cannot be immediately transmitted over the primary DCN.
The secondary path of the preferred embodiment includes two store-and-forward servers. The first store-and-forward server is operatively coupled to a DEM server on the sending side of the data network. The second store-and-forward server is operatively coupled to a DEM server on the receiving side, and also to the first store-and-forward server. In operation, when the primary path is unavailable, the sending-side DEM server transmits DEMs from the sender MCD to the first store-and-forward processor, where they are stored. Subsequently, the first store-and-forward processor delivers the DEM to the second store-and-forward processor. The second store-and-forward processor then sends the DEM to the receiver-side DEM server where it will be delivered to a receiver MCD.
The secondary path for DEM transmission allo
Dutra Antonio
Kamen Benjamin
Nandyal Omprasad S.
Storch Randy S.
Wegner Martin T.
Ho Duc
Hsu Alpus H.
Net2Phone, Inc.
Shaw Pittman LLP
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