Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-08-11
2003-04-08
Vu, Huy D. (Department: 2665)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S474000, C379S088010
Reexamination Certificate
active
06546009
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of telecommunications and related systems. More particularly, the invention is directed to a method of more effectively conducting telephone communications over a computer network, such as the Internet.
In modern network communications, data is typically sent from one point to another using established protocols and standards. These protocols and standards allow equipment from various manufacturers and of various designs to exchange data without the need for special interfaces or conversion processes and the like.
A well established way of sending data over a computer network is to partition the data into small packets having a regular format. Each packet, also known in the art as a datagram, includes an electronic address which is used to route the packet across the network to its designation. The packets are then reassembled at the destination and the data restored to its original or some other prearranged format.
Data communications over the Internet, for example, are conducted in accordance with the Internet Protocol (IP) suite. The IP suite provides for the transmission of packets from source to destination through the various interconnected networks which form the Internet. While the IP suite does not guarantee delivery of each packet, the integrity of the data carried by the packet, or the order in which the packets arrive at the destination, it does provide error protection for some of the critical information within the packet.
FIG. 1
illustrates the format of an IP packet. The packet includes a header portion
1
, which carries control information about the packet, and data portion
2
, which contains the data being carried by the packet. Header portion
1
typically has a fixed format and length while data portion
2
may vary in length.
FIG. 2
is a more detailed illustration of the format of an IP packet with header portion
1
and data portion
2
. As shown in
FIG. 2
, Byte
0
of header
1
includes a 4-bit Version field which indicates the format of the Internet header and a 4-bit Internet Header Length (IHL) field which indicates the length of the Internet header in 32-bit words.
Byte
1
is an 8-bit Type Of Service Field which indicates the type of service which is to be given to the packet.
Bytes
4
and
5
form a 16-bit Total Length field which indicates the total length of the packet (including header and data) measured in octets.
Bytes
6
and
7
form a 16-bit Identification fields which contains a value assigned by the sending device to aid in assembling the packets.
Byte
8
includes a 3-bit Flags field which contains flags controlling fragmentation of the packet and a 13 bit Fragment Offset field which indicates where in the packet this fragment belongs.
Byte
9
is an 8-bit Time To Live field which places a limit on the life span of the packet.
Byte
10
is an 8-bit Protocol field which indicates the protocol associated with the data in the data portion of the packet.
Bytes
11
and
12
form a 16-bit Header Checksum field which represents a checksum computed on the packet header field only.
Bytes
13
-
16
contain a 32-bit IP address which specifies the Source Address of the packet.
Bytes
17
-
20
contain a 32-bit IP address which specifies the Destination Address of the packet.
Bytes
21
-
22
form a variable length Option field.
Byte
23
is a Padding field.
The source and destination IP addresses contained in the packet header are divided into two fields, a network-identifier and a host-identifier. The network-identifier specifies a particular physical network in the Internet and the host-identifier specifies a particular device attached to the specified physical network.
In order to reach its destination, an IP packet may have to traverse a variety of different physical networks. While an IP packet is in a given physical network, it is transported in the same manner that the physical network transports any kind of data. For example, one common kind of physical network is a local area network (LAN) which uses the Ethernet® protocol. In the Ethernet protocol, data moves in packets called “frames”. Each frame has a preamble; a destination Ethernet address; a source Ethernet address; an ethertype field, which specifies a type of the protocol; a data field, which carries the data; and a frame check sequence, which is an error checking code. When an Ethernet frame is carrying an IP packet, such as illustrated in
FIG. 1
, the packet simply occupies the data field of the frame.
Implementations of telephony systems over computer networks, such as the Internet, are now starting to emerge. One of the problems associated with present implementations, however, are the inherent delays associated with filling a packet with telephony data. These delays degrade the quality of the voice communication to the point that, in many cases, it is not acceptable to the consumer.
Prior art attempts to reduce delay focused on optimizing the packing of packets to provide the maximum total bandwidth for data transmission. See for example, U.S. Pat. No. 5,606,561. Such methods stream data well but do not provide for the delays associated with the conversational nature of a telephone call.
Accordingly, there is a great need in the art for an improved method of conducting telephony communications across a network.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to obviate the above-noted shortcomings and disadvantages of present methods of conducting telephony communications across a network.
It is a further objective of the present invention to provide an improved method of conducting telephony communications across a network without imposing inconvenience to the user.
It is a still further objective of the present invention to provide an improved method of conducting telephony communications across a network which is economical to implement and simple in operation.
It is a further objective of the present invention to provide an improved method of conducting telephony communications across a network which is more economical than prior art approaches.
It is a still further objective of the present invention to provide an improved method of conducting telephony communications across a network which can be readily implemented in an existing system.
REFERENCES:
patent: 5051983 (1991-09-01), Kammerl
patent: 5148429 (1992-09-01), Kudo et al.
patent: 5606561 (1997-02-01), Scheibel, Jr. et al.
patent: 5703902 (1997-12-01), Ziv et al.
patent: 6049537 (2000-04-01), Proctor et al.
patent: 6064653 (2000-05-01), Farris
patent: 6115357 (2000-09-01), Packer et al.
patent: 6014385 (2000-11-01), Ayanoglu et al.
Begeja Lee
Berkley Andrew J.
Berkley David Arthur
AT&T Corp.
Ho Duc
Vu Huy D.
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